Any website that shows which opening a certain player struggles against?

Opening tree happens to be the website you are looking for, in it you use a database of games or someone's Lichess or chess.com username to get detail about their games. It shows frequency, last played, best win, worst loss, win-loss stats and performance. It also have have fatabases of famous players in it. Checking Anand's games as black, after playing 1.e4 2.c5 3.Nf3 his worst performance is in Sicilian Defense: French Variation (elo performance 2644) with score 107/173 and worsst loss was Ljubojevic - Anand 1998.

Overall, its a nice free website.


Is it true that Queen's Gambit tends to have positional play and King's Gambit A tactical one?

It depends a little. The Queen's Gambit can lead to very lively play, if both parties are willing, but it's easier to turn it positional, as the Queen's Gambit is more of a "pseudo-gambit" than the King's Gambit; White will almost always be able to regain his pawn if it's taken, even without going all out for blood.

The King's Gambit is different. White opens up lines in front of his own king, and in order not to get into a worse position, White will have to play very energetically, as it's more difficult to regain the lost pawn. If White loses his initiative without regaining his sacrificed pawn, things can turn very ugly.

So it's more a matter of White being forced to be prepared to play that way in the King's Gambit, as opposed to the Queen's gambit, as White in the latter opening doesn't need to worry as much about being worse if his attack doesn't go through.


How fast can checkmate occur by just moving the king?

Here is a starter solution in 7 moves.
Can we do better?
[FEN ""]

1.g3 e5 2.Bh3 Ke7 3.Bxd7 Kxd7 4.Kf1 Ke7 5. Kg2 Ke6 6.Kh3 Kf6+ 7.Kh4 Kg6#

If this is best, interestingly, the play is almost forced. The only variations are 4... Kd6 or 4... Ke7 in the line above. There is also 4... Ke6 and 5... Kf5, or 3. Kf1 Kd6/Ke8 4. Bxd7 Kxd7 5.Kg2 Ke6, etc. Only five possible move orders with such a minimal stipulation would be quite nice.


Is there a standard system of classification of games?

Such a system doesn't exist exactly, but a few similar concepts do. There are many reasons, but the main reason is that it's not possible to classify chess games like this in any useful way.
Yes, you could classify them based on the first move -- but who cares? Only 1.c4, 1.d4, 1.e4 and 1.Nf3 are really important, and they often transpose into each other (1.d4 is followed by 2.Nf3 quite often, and 1.Nf3 is followed by 1.d4).
For a system like this to be useful, it needs to have some properties:

It should be based on the games of really strong players, after all they are the ones who care about this sort of thing
Some people have really amazing memories, but even they are quickly overwhelmed by chess. It has to be of a practical size
It has to help you find good moves at the board, as that is really the only thing that matters for chess players

And a whole chess game is quite long. Some parts of it can be categorized, others defy such attempts completely. So in chess it is positions that can sometimes be classified, not entire games.
I can think of three phases that can be treated like this:

The early opening. Theory can be worked out exactly, because the starting position is known. Related lines will have things in common but also important differences, and they mostly just need to be memorized. Opening names like in ECO are mostly so you can find in which book you need to look up your theory.

Most middlegames (not all) can be usefully classified based on the central pawn structure. That's the main thing most players will think of. In e.g. a position where one side has "the isolated queen's pawn" (a pawn on d4 and no pawns on the c- and e- files, after the opening, and the other side say a pawn on e6 and no pawns on the c- and d- files) has a list of standard plans that people know by heart. The actual positions differ, the tactical details will matter, but recognizing lots of types of position like this and knowing the standard plans helps. It is what books like Mauricio Rios' Chess Structures are about.

Very simplified Endgames can again be classified and studied. Many positions with bishop + pawn vs bishop have similar ways for trying to promote the pawn or stopping it, and knowing about them helps (and it helps to decide whether you can safely trade down to this endgame in a particular case), and so on for lots of other material distributions. Many, many books are written about endgames in such a fashion.

But there are also phases of the game in between the early middlegame and the late endgame, and they lend themselves much less to classification. The differences are more important than the things games have in common, here.
And there is no "standard" classification for any of this. It's an art, more knowledge of this sort of thing (and the skill to apply the knowledge) is what separates strong players and even stronger ones.


[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 "]

1. e4 b6 2. d4 Bb7 3. Bd3 f5 4. exf5 Bxg2 5. Qh5+ g6 6. fxg6 Nf6 7. gxh7+ Nxh5 8. Bg6++

One possible trap for black is in the Matinovsky gambit which starts with ... 3.f5.


FICS has a "takeback" option; other sites may have something similar.

The link gives full details but the idea is that you type takeback n to request undoing n half-moves. Either player can do this so, if you make a mouse-slip, you can just type takeback to ask your opponent to undo that move (n=1 is assumed if you don't specify); if your opponent makes a mouseslip, you can still type takeback to allow them the chance to undo. In the second case, you don't have to wait for your opponent to reply while your clock ticks away: if you make your move, the takeback is modified to takeback 2 so your opponent has the offer of undoing both his mistake and your reply to it. When offered a takeback, you can either accept or decline; making a move automatically declines. Accepting a takeback also resets the clocks to what they were at the moment when the mouse-slip was made.

On sites where this is not available, I'd recommend not making a dummy move, unless you were already in a losing position. You don't know that your opponent will behave honourably. They might exploit your generosity. I also wouldn't offer a draw unless, perhaps, a draw would have been a reasonable outcome before the mouse-slip. If your opponent was already losing, why should they gain half a point just by making a mouse-slip?


Endgame technique: How to win with rook + g and h pawn vs rook?

As we can see from the other answers, there are two things you should avoid: 1) The pawns getting blockaded. 2) Your king getting cut off from the pawns.

It is not the only way to win, but as a matter of technique it is a good thing to advance the h-pawn before the g-pawn. In this way your king can use the g-pawn to hide both from checks from the side and checks form behind. But first use the rook to chase the opponent king as far back as possible.

Example:

[FEN "8/8/7k/R7/6PP/6K1/8/1r6 w - - 0 1"]
[Title "Rook endgame g+h"]

1. Ra6+ Kg7 2. h5 Rb3+ (2... Rg1+ 3. Kh4 Rh1+ 4. Kg5) 3. Kh4

The checks will stop and you can think of the next step.

[FEN "8/6k1/R7/7P/6PK/8/8/1r6 w - - 0 1"]
[Title "Rook endgame g+h"]

1. Ra7+ Kg8 (1... Kh6?? 2. g5#)  (1... Kf6 2. g5+ Kf5 3. Rf7+ Ke6 4. Rf6+ Ke7 5. h6) 2. h6 Rb5 3. g5 Rb1 4. Kh5

Here I would again chase the king away before advancing the h-pawn another step.

If the g-pawn is pinned there is no point in giving a check first.

[FEN "8/7k/R7/7P/1r4PK/8/8/8 w - - 0 1"]
[Title "Rook endgame g+h"]

1. h6 (1.Ra7+ Kh6) Rb1 (1... Rb5 2. g5 Rb1 3. Ra7+ Kg8 (3... Kg6 4. Rg7+ Kf5 5. h7))2. Kh5 Rb5+ (2... Rh1+ 3. Kg5) 3. g5

In this way you can advance slowly rank by rank. Towards the end black will have to defend passively to avoid mate at the back rank. Just for the fun of it I would try to end the game with a knight or bishop promotion like in my answer to this question.

[FEN "r6k/8/6PP/5RK1/8/8/8/8 w - - 0 1"]
[Title "Rook endgame g+h"]

1.Rf8+ Rxf8 2.g7+ Kh7 (2...Kg8 3.Kg6) 3.gxf8=N+!(3.gxf8=B!)(3.gxf8=Q??)(3.gxf8=R??)


How many times should I let my opponent know they forgot to press their clock?

Its a matter of opinion, and much more likely to occur at the beginner or amateur levels of chess.

I believe it is best to show the high levels of sportsmanship and notify them immediately for the first couple of times they forget to press there clock.
If they continue to forget to press the clock, start by waiting 1 minute, followed by 2 and 3 etc. … If it's becoming a serious problem and your position (clock and board) is sufficient, I would consider going for a walk to look at other games in attempt to drill the point home.

Drilling deeper into the matter, when players don't press their clock, they are costing yourself and themselves XX seconds from increments and can cause problems when playing games with multi time control periods.


Do chess AIs still use old-style opening books?

Chess engines are, of course, able to analyse opening positions and come up with reasonable moves, but opening books still come with some advantages:

Moving instantly in the opening saves a lot of time, which can be spent on more complex moves later on in the game.
Some more subtle theoretical moves in the opening may be missed without an opening book.

In engine vs engine testing, the overwhelming majority of games are conducted starting from an opening position, but the engines themselves are not allowed their own books.

When playing a human, many chess applications use books, but delay their move anyway to give the impression that the program is thinking. This has the advantage of allowing said application to offer a greater variety of openings, whereas relying on the engine's analysis would lead to repetitive games.

In analysis, it is common for to only start from the first move made out of book, because it is likely that moves made in-book are reasonable.

Lichess is somewhat unique in that it uses the engine to analyse every move rather than using a book for the first moves. The analyses of many opening positions are stored in the cloud to avoid duplicating work in the opening (you may see, for example, "Depth 39 [CLOUD]").


I'm assuming your aim in practicing tactics is to improve your game performance.
In that case, I would recommend you treat each problem not as a puzzle, but as a real game situation, because your goal is to be able to spot tactics OTB, without knowing whether or not a tactical shot exists or not.

Thus, you should apply the thinking process you would use in a real game to the puzzle, and just try to play the move you would in a real game.

This means that you would, after a quick evaluation of the initial position, look for (1) Forcing moves, checks/caps/threats, (2) logical, positionally sound options that increase your activity/decrease opponent's activity. Then, you should calculate and evaluate these candidate moves one by one, and determine which one is the best. This is how you would play in a real game, and thus your tactical training should be like this.

If you can't spot the tactic (get the problem wrong), then you know that something is wrong with your thinking process, and you can correct it immediately. For example, if you spotted all the appropriate candidate moves, but, after calculation/evaluation, didn't find a winner, and thus settled for a "positional" move, then you know that there's an issue in your calculation; maybe you didn't remember to find all candidate moves at every move, and thus missed something. Or perhaps you couldn't visualize a long sequence, and now you know you have to get better at this.

This is assuming you know how to improve every aspect of your thinking process. There are many free online resources, particularly youtube, that tell you how to train to improve certain things.

I think that 10-20 difficult puzzles is plenty, as long as you apply your thinking process to each, and remember to diagnose/improve your thinking process at the end of each puzzle. Also, remember that in a real game, you have around 3 minutes per move. In critical situations, you may use more, but try not to use more than x minutes for a move, if you not spend more than x minutes on the position in a game.

Also, playing blindfold chess is not bad. Blindfold chess is one way to improve your visualization skills, which is crucial for calculation.

I am a USCF expert rated player.


Exchanged Slav defense. Gambit the c6 pawn. Why not?

In the chessok opening tree there are 28 games with this gambit. Going by the computer evaluation it seems to be playable, but the score is atrocious (>80% for white).

So here you have a gambit that is pretty unknown, scores horribly and can easily be ignored if white is not in a mood for adventures. Also it doesn't seem to lead to dangerous complications as far as I can see. There is no automatic attack on the white king, in the worst case white just returns the pawn.

All in all not very surprising that it is rarely played.


Attempting to create a retraction problem

Could white have just played Bg4 from somewhere without capture? Black’s prior move was Ke5-e6. This can be fixed by a shifting wNg3 to e3 and wBd4 to g3 in its place. This stops other cooks where White has just given a discovered check. Adding a further wN on c6 also prevents any retractions with the White rook, and the Black king moving to e5.
[FEN "8/3R2Kp/4kP1P/3R3P/6BP/4N1BP/P1P4P/8 w - - 0 1"]

A key point is that retracting 1. e5xf6e.p. f7-f5 2. B~g4+ Kf5-e6 3. N~e3+ works, as wPe5 blocks wRd5 from attacking f5, and so bK on f5 only endures a single check (from wNe3).
General chess problem solving engines e.g. Popeye don’t currently offer retraction capabilities. It might be possible to solve Edith Baird style retractors though, but not ones with retro logic.
The database pdb.dieschwalbe.de contains lots of retractor problems. Type k='help retractor' in the search box, and hit Overview to begin your journey in this amazing resource.
Addendum #1 11/30/2020: Here is a sound version by Rewan, a correction of my above "correction"! It is certified correct by Mario Richter's Rawbats program. The above version is incorrect due to 1. Rf5-d5 being a possible last move for White as well, and, furthermore, multiple stalemating moves afterward.
[FEN "8/3R2Kp/2N1kP1P/3R3P/3B2BP/6NP/P1P4P/8 w - - 0 1"]

Addendum #2 11/30/2020: I found a bug with my earlier proposed version, and also a way to make this much more economical. The new solution is proved correct (aka "C+") by Mario Richter's legendary Rawbats program.
[FEN "8/3R2K1/4kP1P/3R3P/3P2BP/4N1BP/7P/8 w - - 0 1"]

White has made 15 pawn captures, so if the last move (which must have delivered check) was by an officer, then it was not a capture, so Black has no prior move, and the position is illegal. The only possible last move is en passant, R: 1. e5xf6ep# so we conclude that this definitely was the case.
(For retractors, one does not need to prove that the prior move was definitely a double hop in order to allow the en passant retraction. In this case, the logic goes the other way round: the en passant proves the double hop.)
Now the retraction goes R: 1. ... f7-f5 2. B~-g4+ Kf5-e6/Ke7-f6 3. S~e3+/R~-d7+ etc.
Instead of the first retraction, White can play 1. Se3-f5= for stalemate.
(It could be possible to generate this effect in a position in which White is not delivering check, or in which one can retract uniquely further.)


Three questions on GM Larry Kaufman's article about the average relative value of the chess pieces

When Kaufman was doing the research, he was studying specific imbalances.  Basically he searched his database for high level games that featured a specific material imbalance and then determined which side won.  That's a slight oversimplification of his method, but the gist is that the research didn't actually give point values for each of the pieces, merely the average number of pawns required to re-balance the material.

To address your second question, I agree that the fact that minor pieces can't win on their own needs to be considered, but it's very easy during the game to keep track of this possibility.  It's far more convenient to know that a piece is better than 3 pawns in the opening and the middle game but worth less than 3 pawns in the endgame.  Having two values for the two separate situations is more conducive to quick evaluations than trying to say that the pawns are "gaining" value once an endgame is reached.

For your last question, human players don't evaluate positional nuances in terms of point values.  Humans will think things like "white is better because he has the d5 square" or "black is better due to the bishop pair", but rarely will a human think "the d5 square is worth 0.30" or "the bishop pair in this position is worth 0.44".  Computers, on the other hand, rely solely on this pure number crunching.  Basically the computer values are calculated in light of the fact that enough positional advantages eventually outweigh some material considerations, but humans generally separate the material calculations and the positional valuations.  In the human case, it's reasonable to think in half pawns and in extreme cases in quarter pawns, but at the end of a long variation, whole numbers become more expedient.  Computers could not care less as to the exact values, so the "real" values can be used when developing engines while humans still tend to rely on rounded values.


What will/should the arbiter do if the side which cannot theoretically lose resigns?

The first thing to note is that the FIDE Laws of Chess are silent on this. Resignation at any time in any situation is allowed and immediately ends the game:

5.1.2 The game is won by the player whose opponent declares he resigns. This immediately ends the game.

Other methods of losing are qualified in some way. For example, checkmate is only valid if the preceding move was legal, a game where one player runs out of time is only a loss if there is some way (i.e. helpmate) that the opponent can deliver checkmate.
However this is not the end of the story. There are also the Anti-Cheating Regulations. They say:

These regulations deal with the investigation of suspected cheating incidents.
“Cheating” in these regulations means:
i) the deliberate use of electronic devices (Art. 11.3.2 FIDE Laws of Chess) or other sources > of information or advice (Art. 11.3.1 FIDE Laws of Chess) during a
game; or
ii) the manipulation of chess competitions such as,
including but not limited to, result manipulation, sandbagging, match fixing, rating fraud, false identity, and deliberate participation in
fictitious tournaments or games.

If the arbiter believes the resignation was a result of ineptitude then it should stand. There have been examples of top GMs resigning drawn positions through ignorance and ineptitude.
If the arbiter suspects some form of cheating or receives a complaint of such then this should be investigated. These things also happen.


Mutual Zugzwangs & Longest Checkmates (DTM, DTC and DTZ) in the endgame KRPP vs. KRP

I have been able to find information for everything asked of. However, I have not found any large surveys; just mere snippets.

Mutual Zugzwangs

This page on http://ruszchessstudies.blogspot.com/ provides several examples of half-point mutual zugzwangs along with some general information. Here is one of them.
[FEN "3K4/P7/P7/8/8/8/R5rp/3k4 w - - 0 1"]

As for full point mutual zugzwangs, one such position was given by @mbourzut in this a Rybka forum. This forum contains numerous drawing and winning positions; a small survey.
[FEN "8/8/2P5/2r1p3/RK1kP3/8/8/8 w - - 0 1"]

DTC

The record for the longest DTC sequence is 79 moves, according to page 24 of this arves.org PDF. It contains further information KRPP-KRP endgames.
 [FEN "8/r7/2K3p1/k7/8/8/P4P2/1R6 w - - 0 1"]

 1. Rb7 Ra6+ 2. Kc5 Ka4 3. Rd7 Ra5+ 4. Kd4 Rf5 5. Ke3 Kb4 6. Rd6 Re5+ 7. Kd4 Rf5 8. Rb6+ Ka3 9. Ra6+ Kb4 10. Ke3 Re5+ 11. Kf3 Rg5 12. Re6 Ka3 13. Re2 Kb4 14. Kf4 Rg2 15. Ke3 Rg1 16. Rc2 Re1+ 17. Kf4 Rg1 18. f3 g5+ 19. Ke3 Re1+ 20. Re2 Rc1 21. Rg2 Rc5 22. Rb2+ Ka3 23. Rd2 Rf5 24. Rc2 Kb4 25. Rc7 Kb5 26. Rc8 Re5+ 27. Kf2 Kb6 28. a4 Rd5 29. Rb8+ Kc6 30. Kg3 Rf5 31. Re8 Kd7 32. Re4 Rd5 33. Kg4 Kd6 34. Re8 Rc5 35. Kh5 Rf5 36. Re3 Ra5 37. Ra3 Kd7 38. Kg6 Ke7 39. Ra2 Ke8 40. Kf6 Kf8 41. Ra3 Ke8 42. Re3+ Kf8 43. Re4 Kg8 44. Ke7 Kg7 45. Kd6 Kf6 46. Kc6 Ra8 47. Kb5 Rb8+ 48. Kc4 Rc8+ 49. Kb4 Rb8+ 50. Ka3 Rh8 51. Re3 Rh3 52. Rb3 Ke7 53. a5 Kd8 54. Ka4 Rh4+ 55. Rb4 Kc8 56. a6 Rh6 57. Ka5 Rh7 58. Rb6 Rg7 59. Rb7 Rg8 60. Rb5 Rg7 61. Rb6 Rf7 62. Kb4 Rf4+ 63. Kb5 Rf5+ 64. Kc4 Rf4+ 65. Kd5 Kc7 66. a7 Ra4 67. Rf6 Kb7 68. Rf7+ Ka8 69. Ke5 Ra2 70. Rg7 Rg2 71. Ke4 Rg3 72. Ke3 Rg2 73. Kd3 Rf2 74. Ke4 Re2+ 75. Kf5 Re3 76. Kg4 Re4+ 77. Kg3 Rg4+ 78. Kf2 Rc4 79. Rxg5

DTM

The record for the longest DTM sequence is 218 moves. It can be found on page 105 of this PDF, created by Guy Haworth, about tablebase length records.
[FEN "8/k1P5/8/8/1R5P/7p/r7/1K6 b - - 0 1"]

1... h2 2. Kxa2 h1=Q 3. c8=R Qd5+ 4. Kb1 Qa5 5. Rcc4 Qe5 6. Ra4+ Kb6 7. Rc2 Kb5 8. Rac4 Qg7 9. Rc5+ Kb4 10. R2c4+ Kb3 11. Rc3+ Kb4 12. R5c4+ Kb5 13. Rc7 Qg1+ 14. Ka2 Qg2+ 15. Ka3 Qg1 16. Rb7+ Ka6 17. Rb2 Qa1+ 18. Kb3 Qe1 19. Rc6+ Ka7 20. Rc4 Qe6 21. Rbc2 Ka6 22. Ka4 Qd7+ 23. Rc6+ Ka7 24. Kb3 Qd5+ 25. Kb4 Qh1 26. Rc7+ Ka8 27. R7c4 Qh3 28. Ka4 Ka7 29. Rb4 Qd7+ 30. Ka3 Qd3+ 31. Kb2 Qd5 32. Rbc4 Qh1 33. Ka2 Qd5 34. Ka3 Qd6+ 35. Kb2 Qf6+ 36. Kb1 Qb6+ 37. Ka1 Qg1+ 38. Ka2 Qg8 39. Kb2 Qd8 40. Ra4+ Kb6 41. Rb4+ Ka5 42. Rbc4 Qh8+ 43. Kb3 Qg8 44. Ka3 Qf8+ 45. Rc5+ Ka6 46. h5 Ka7 47. Kb4 Kb6 48. Kb3 Qf3+ 49. Ka2 Qf7+ 50. Kb2 Qf6+ 51. R2c3 Qf2+ 52. Ka3 Qf8 53. Ka4 Qf1 54. Rc6+ Kb7 55. h6 Qa1+ 56. Kb4 Qb2+ 57. Rb3 Qd2+ 58. Kc5+ Ka7 59. Ra3+ Kb7 60. Rb6+ Kc8 61. Ra8+ Kc7 62. Ra7+ Kc8 63. Rc6+ Kb8 64. Ra4 Kb7 65. Rb4+ Ka7 66. Rc4 Qe3+ 67. Kd5 Qd2+ 68. Ke5 Qe3+ 69. Kf5 Qd3+ 70. Ke6 Ka8 71. Rc8+ Ka7 72. R8c7+ Ka6 73. h7 Qh3+ 74. Kf6 Qh6+ 75. Kf5 Qh3+ 76. Kf4 Kb5 77. Rc3 Qh1 78. Rb3+ Ka6 79. Rd7 Qh4+ 80. Ke5 Qg5+ 81. Kd4 Qf6+ 82. Kd3 Qg6+ 83. Kc3 Qg3+ 84. Kc2 Qg2+ 85. Kb1 Qf1+ 86. Ka2 Qe2+ 87. Ka3 Qe5 88. Rbd3 Qa1+ 89. Kb3 Qb1+ 90. Kc4 Qc1+ 91. Kd5 Qg5+ 92. Ke4 Qg4+ 93. Ke3 Qg5+ 94. Kf2 Qh4+ 95. Ke2 Qe4+ 96. Kd1 Qg4+ 97. Kc1 Qc4+ 98. Kd2 Qf4+ 99. Re3 Qf2+ 100. Kd3 Qf5+ 101. Kc3 Qc5+ 102. Kd2 Qa5+ 103. Rc3 Qa2+ 104. Ke3 Qe6+ 105. Kf2 Qb6+ 106. Re3 Qf6+ 107. Rf3 Qb6+ 108. Kg2 Qg6+ 109. Kf1 Qb1+ 110. Ke2 Qb5+ 111. Ke3 Qe5+ 112. Kd2 Kb5 113. Rdf7 Qd5+ 114. Ke2 Qe5+ 115. Kf1 Qh2 116. R3f4 Ka5 117. Ke1 Kb5 118. Kd1 Qh5+ 119. Kd2 Qd5+ 120. Ke2 Qe6+ 121. Kf2 Qh3 122. R4f5+ Ka4 123. Ra7+ Kb4 124. Rb7+ Kc4 125. Rc7+ Kb4 126. Rf4+ Kb5 127. Rfc4 Qh2+ 128. Ke3 Qh1 129. Kd2 Kb6 130. Kc2 Qa1 131. R4c6+ Kb5 132. Rc3 Qa2+ 133. Kc1 Qa1+ 134. Kd2 Qb2+ 135. Ke3 Qh2 136. Kd3 Kb6 137. R3c6+ Ka5 138. Rc5+ Kb4 139. Rc4+ Ka5 140. Kc3 Kb6 141. Kb3 Qh1 142. R4c6+ Kb5 143. Rc2 Qf3+ 144. Kb2 Qh1 145. Rf2 Qh4 146. Rf3 Qh2+ 147. Kb3 Qh1 148. Rf5+ Kb6 149. Rcf7 Kc6 150. R7f6+ Kd7 151. Kb2 Qh2+ 152. Kc3 Ke7 153. Rc6 Qg3+ 154. Kc2 Qg2+ 155. Kb3 Qg3+ 156. Rc3 Qb8+ 157. Kc4 Qc7+ 158. Kb4 Qb6+ 159. Rb5 Qd4+ 160. Kb3 Qd1+ 161. Ka3 Qa1+ 162. Kb4 Qb2+ 163. Kc4 Qh2 164. Kb3 Kd6 165. Rb7 Qh1 166. Rbc7 Ke5 167. R3c5+ Kd4 168. Kb2 Qh6 169. Rb5 Qf8 170. Rbb7 Ke4 171. Rc4+ Ke5 172. Rc3 Qf2+ 173. Kb3 Qh2 174. Re7+ Kd6 175. Rec7 Qh1 176. R3c5 Ke6 177. Kb4 Kf6 178. Rd7 Ke6 179. Rcd5 Qe1+ 180. Kb5 Qb1+ 181. Ka6 Qa1+ 182. Kb6 Qb2+ 183. Rb5 Qh8 184. Rb7 Kd6 185. Rf5 Ke6 186. Rh5 Qd4+ 187. Ka6 Qa4+ 188. Ra5 Qe8 189. Re7+ Qxe7 190. h8=Q Qd6+ 191. Kb5 Qd5+ 192. Kb4 Qd6+ 193. Rc5 Qb6+ 194. Rb5 Qd6+ 195. Kb3 Qd1+ 196. Ka3 Qd6+ 197. Rb4 Qd3+ 198. Ka4 Qc2+ 199. Rb3 Qc4+ 200. Ka5 Qc5+ 201. Ka6 Qc4+ 202. Rb5 Kd7 203. Qh5 Kd6 204. Qf5 Kc7 205. Qc5+ Qxc5 206. Rxc5+ Kd7 207. Kb6 Kd6 208. Rh5 Ke6 209. Kc6 Kf6 210. Kd6 Kg6 211. Rd5 Kf6 212. Kd7 Kf7 213. Rd6 Kf8 214. Ke6 Kg7 215. Ke7 Kg8 216. Kf6 Kh8 217. Kg6 Kg8 218. Rd8#

DTZ

The DTZ length records can be found in the Syzygy endgame tablebases. Here are the record positions without the moves.
[Title "Longest Winning DTZ, Without The 50-Move Rule-136 ply"]
[FEN "6k1/8/3pP1R1/3P4/8/1K6/8/3r4 b - - 0 1"]

[Title "Longest Winning DTZ, With The 50-Move Rule-100 ply"]
[FEN "2r5/8/8/2pP3K/2P5/3R2k1/8/8 b - - 0 1"]

[Title "Longest Losing DTZ, Without The 50-Move Rule-124 ply"]
[FEN "1k6/4K3/5R2/8/5P2/1p6/3P4/4r3 w - - 0 1"]

[Title "Longest Losing DTZ, With The 50-Move Rule-63"]
[FEN "8/8/8/K7/P5R1/1k6/P1p5/r7 b - - 0 1"]


When losing in blitz, is it rude to play to win on time?

No it's not. Your opponent spent more time to reach a winning position and you spent less time to get time advantage. It's quite fair to use your time advantage over your opponents position advantage.

Time control is a part of chess.


What is a more efficient thinking process?

When you learn an opening you learn sequences of moves and the ideas behind those moves. If your opponent follows "book" then you don't have too much to think about. Probably just "Which variation am I going to play today? Am I feeling like a quiet strategic game or a wild tactical game?"

If your opponent plays a move you are not familiar with then there are two questions and two situations to cover.

1) You are playing a sharp, tactical opening where there are lots of threats and he didn't counter your threat and isn't counter threatening anything. In that case carry out your threat!

2) You are playing a quieter opening in which you are both just developing your pieces. In that case, after checking for threats, ask yourself if his move stops you developing the way you wanted. If it doesn't then carry on. If it does then work out how you now need to develop the rest of your pieces.

In the middlegame it is a bit different. When it is your turn you do need to calculate what you evaluate are your opponent's best replies.

When it is your opponent's turn it depends how many good looking possibilities he has. If it looks like just one or two forced or "best" replies then stay in your seat and calculate those. If it is a complicated position with lots of equally likely looking possibilities then either take a step back and look at the position from a long term strategical point of view or save your energy, go get a cup of coffee or glass of water or relax looking at other games whilst keeping half an eye on whether your opponent has moved yet.


Where can I find a free list of a strong GM (2575+) annotated games?

www.chessgames.com has a big collection of annotated games.


Why is the f6 pawn break in Advanced French so important for black?

I am new to french (so forgive me if the question seems elementary) I've just came across the pawn break f6 for black in the french advance variation, and I find the pawn break quite dubious for me for several reasons

You must understand one whole new concept of chess modern strategy : Weakness is not a weakness if it can not be exploited.

And another thing: Opening theory chooses only the strongest moves as mainlines.

These moves are the strongest moves known today, so if Black is willing to play with a backward pawn, then be sure he has very good compensation for that!

So you have a backward e-pawn, so what? What are the other features of the position?

Can you get active piece play for this weakness?
How easy is for White to attack it? Does he have to give up "something" ( development/control of a key square/etc ) in order to attack it?
Can you sacrifice that pawn in the near future for strong pressure/initiative?
Is it really a weakness or is it simply ugly?

Once you change your point of view like this, you will see the other potentials that you have totally neglected or simply underestimated.

  When we are attacking the opponent's pawn chain, we are told that to attack the pawn chain, the best way is to attack its base. But in this case, black seems to be voluntarily giving up his pawn chain, as the base of the f7-e6-d4 pawn chain is at f7. Isn't black self-destructing his pawn chain in advancing the f-pawn, as white can now attack e6 pawn?

Can White really attack the e6 is the question here that is important. The modern practice proves that White can not do this advantageously. I have provided an explanation why, and have posted some examples below.

  After the inevitable exchange of the pawns (exf6 Rxf6), to me, black is left behind with a backward pawn (e6) and its is easy to be exploited by white. My question is: how is the backward pawn favouring black's position, and why is gxf6 not played as black can get rid of the backward pawn by playing e5 on the next move.

Black has clear math behind this:

White has lost a tempo with e5 by playing twice with a pawn;
White is passive and for now only maintains space advantage;
Because of #1 and #2, White needs time to finish development so he can "cash in" his space advantage;
White pieces are slightly misplaced -> Nb1 belongs at c3 but the pawn is there, Bc1 should go to g5 or e3 but is hindered by ...Qb6;

Now the important part:

If Black removes d4 + e5 chain then his superior development will be felt and he will get mobile central phalanx -> mobile center phalanx + superior development/piece placement = high chances to win.

This is very stressful moment for White, and he needs accurate play just to survive. He needs to finish his development but his strong pawn chain is gone. That is why he has no time to attack e5, it is just too dangerous.

So you see, Black will follow ...f6 with ...c5 in order to get his central pawns rolling, and since he will get his pieces ideally placed, the initiative he obtains might be decisive.

Furthermore, f-file + Qb6 + Nf6 + Bc5 make tremendous pressure at f2. There is thematic ...Nxf2/Bxf2 sacrifice with subsequent ...e4 that regains the piece but retains the initiative. You have never mentioned that you are aware of this plan! Without knowing these plans it is easy to look at Black strategy as bad. Now you understand why ...gxf6 is usually a mistake.

  If it's argued that f6 develops the black's light-squared-bishop by the manoeuvre Bc8-d7-e8-h5, why can't black jus play b6 and fianchetto the bishop or even play Ba6?

On b6 usually sits Black queen, so the plan you mentioned fails. She is so well placed there, while ...Ba6 would achieve little. With the pawn center rolling ( after Black plays ...c5-cxd4 and ...f6-fxe5 ) bishop will come into play just in time, and on a good g4 or f5 square with strong effect.

PRACTICAL EXAMPLES OF ABOVE STATEMENTS:

I will quote some theoretical lines form the Advance French just to show you above plans in action. The sample lines are quoted from J.Watson-Play the French 4th edition ( 2012 ) :

[Title "Black demolishes White pawn chain and obtains dynamic piece play"]
[fen ""]

1.e4 e6 2.d4 d5 3.e5 c5 4.dxc5 Nc6 5.Nf3 Bxc5 6.Bd3 f6 7.Qe2! fxe5 8.Nxe5 Nxe5 9.Qxe5 Nf6 10.O-O O-O ( 10...Bd6 11.Qg5 O-O 12.Nc3 e5 13.f3 Be6 ) 11.c4 Ng4! ( 11...Qb6!? ) 12.Qh5 Rxf2 13.Rxf2 Bxf2+ 14.Kh1 Nf6 15.Qe2 Bb6

"and White has some, but not fully sufficient, compensation for the pawn."

Also notice that after 11...Qb6!? sideline if White plays 12.Qe2 Black plays 12...e5! threatening both ...e4 and ...Ng4.

Here is another example:

[Title "Black demolishes White pawn center and obtains equal position"]
[fen ""]

1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Nf3 Qb6 6.Be2 f6 7.O-O fxe5 8. Nxe5 Nf6 9.dxc5 Bxc5 10.Nd3 ( 10.b4? Bxf2+! ) 10...Bd6 11.Be3 Qc7 12.f4 O-O 13.Nd2 e5 ( 13...Bd7! ) 14.fxe5 Nxe5 15.Nxe5 Bxe5 16.Nf3 Bd6 17.Kh1 Bg4 18.Bg5 Kh8 19.Bxf6 Rxf6 20.Nd4 Bxe2 21.Qxe2 Bxh2 22.Rxf6 gxf6 23.Qe6=

The whole point of ...f6 is to demolish White pawn chain so you can start rolling your own central pawns and exploit your development advantage/better piece placement. After ...f6 make sure you can follow up with ...c5 and just open the game. You should be just fine after that.

This is the plan that was not familiar to you, but this plan is the one that "holds" this line "together". If you need further help leave a comment. Best regards.


Rule enforcing a player to move on a turn?

Yes, there is a rule that a player must make a move during her turn. If the player in turn has no legal moves and her king is not in check, then the game is drawn.

  I realize that in a chess game, there is no reason to not move a piece.

Actually, almost all chess endgame theory, and thus a huge part of the whole game of chess is based on the fact that a player has to move a piece during her turn. I'll explain this by a simple example and some handwawing. Consider for example the following endgame:

[title "White to move and win"]
[fen "4k3/8/4K3/4P3/8/8/8/8 w - - 0 1"]

1. Kf6 Kf8 2. e6 Ke8 3. e7 Kd7 4. Kf7 Kd6 5. e8=Q

If, at her 4th move, Black didn't have to move the king, the game would be drawn, as there is no way for White to promote her pawn. However, because Black king has to step away, White gets a new queen and wins the game. (Note that this does not mean that a king and a pawn always win against a lone king; very often the game will be drawn, because also White has to make moves she would not want to make.) A situation like this, where having the turn actually makes your position significantly weaker, is called a zugzwang; for more examples, see for example the Wikipedia article

This and more complex endgames are the reason why one pawn advantage is often enough to win: You can exchange pieces until you get to an endgame where you can then often convert the extra pawn to a win. Very often the winning technique of king and pawn endgames are based on the fact that the winning side can force the losing side's king to step away from defending important squares simply because the king cannot stay on the best square forever. The winning technique of many other endgames is then based on the fact that the winning side can threaten to convert to a winning king and pawn endgame, restricting the options the losing side has.


Is the English opening the most suitable for beginners?

Do these factors make the English opening ideal for beginners?

No. As a beginner it is OK to study the English along with other openings but what you seem to be suggesting, that it be the only white opening a beginner learns, is very bad.

By definition a beginner doesn't know very much about chess and to progress needs to learn much. In openings the standard approach, therefore, is to learn the classics: Ruy Lopez, Italian, Kings Gambit, 4 Knights, Scotch, Sicilian, French, Caro Kann.

You notice these are all e4 openings and the list starts with the reply e5 by black before moving on to other replies. A beginner needs to start by learning about control of the centre in the most direct way. He needs to learn about the importance of development and then tactics.

Some chess teachers would start by teaching the Kings Gambit for this reason. Chess needs to be fun and tactics are fun and most games end because of some missed tactic by the opponent. If you only ever learn how to play calm positions then you will lose all your games where your opponent manages to make the game tactical.

You also seem to suggest a formulaic way of playing the opening. Play more or less the same moves in the English and you will end up in one of two tabiyas which you give. This is also very wrong. One of the key skills a beginner needs to develop is to always consider the ideas and aims of his opponent's moves. Just playing automatic moves will lead to many quick defeats.

There are many ways for black to respond and they give rise to different problems for white which can't be addressed by just playing more or less the same moves. The opening theorist IM John Watson actually wrote 4 separate books on the English because of this. He wrote one book each for black's responses: 1 ... e5, 1 ... c5, 1 ... Nf6 and a catch-all "other replies".

So, no, the English is close to being the least suitable opening for beginners. Better than the Grob, obviously, also better than Bird's, but a long way behind 1. d4 and even further behind 1. e4 openings.


How do strong players know opening ideas, plans, etc?

This kind of book is usually a work of synthesis. The author looks at the available games and takes notice of the various plans employed. It is a matter of noticing and making notes and then writing up a synopsis. An opening book can be written without prior personal experience with this opening. One can also discover a new plan, either by one's own thinking or by looking at the way an engine plays.

Sometimes ideas are transmitted orally. Bologan's book on the King's Indian Defense is by his own admission written on the basis of the notes he took while being tutored by his guru Lanka.


When is it legal to castle moving the rook first?

Unless this is a trick question, I'd say never:

3.8.2 [] This is a move of the king and either rook of the same colour along the player’s first rank, counting as a single move of the king and executed as follows: the king is transferred from its original square two squares towards the rook on its original square, then that rook is transferred to the square the king has just crossed.

The word then implies the king moves first, and the rook second. Also,

4.4 If a player having the move:
4.4.1 touches his king and a rook he must castle on that side if it is legal to do so
4.4.2 deliberately touches a rook and then his king he is not allowed to castle on that side on that move and the situation shall be governed by Article 4.3.1

That would imply that touching both king and rook (but not moving them) commits the player to castling; then, he/she could then move the rook first and only then the king, since that would give the same position on the board as the only legal play at that moment. Still, if I would see that as an arbiter, I'd have a word with the player about this.


How many positions are there in n-pieces endgame tablebases for different values of n?

This depends a great deal on how (and what) you count. In a discussion at the CCRL board, Kirill Kryukov offers the following counts on the number of unique legal positions (NULP) for some small numbers of pieces:

Pieces          NULP
  2                  462
  3              368,079
  4          125,246,598
  5       25,912,594,054
  6    3,787,154,440,416

But it is important to note that his numbers (which he was in fact soliciting independent confirmation of, so take with a grain of salt) depend on his definition of a legal position:

  I use simple definition of legality: 1. Side to move does not give check. (2. No pawns on promotion rank or before the starting rank. 3. Exactly one white king and exactly one black king are on the board).

Thus he doesn't consider the matter of positions actually being reachable from the starting position of chess, for instance. There is a lot of discussion there to go through if you wish.

Another key point is that these position counts take the symmetries of the chessboard into account. With the 2-piece positions, for example, the naive count (which would be reduced a bit for legality, i.e. non-touching kings) would be roughly 64 * 63 = 4,032. The reason his count is so much less is because he is counting unique positions as would be stored in tablebases, where for the sake of saving space positions that are symmetric variants of one another are not counted distinctly. The 462 2-piece positions can be pictured like this (and forgive my ugly drawing):

Taking symmetry redundancies into account, there are only 10 unique squares where our first king could be placed (those within the red border). And then, taking legality and further symmetries into account, there are only so many remaining squares where the second king could be placed (indicated by the numbers, for each of the 10 initial squares). These sum up to the 462 unique positions in question.

To illustrate one case, why is the count 30 for the d4 square? Of the 63 remaining squares, 8 wouldn't be legal. Of the remaining 55, the 5 on the long diagonal are all unique, but the remaining 50 come in 25 pairs of squares whose resulting positions are no longer unique with respect to the symmetries of the board (in particular, they are mirror images of one another when reflected across the long diagonal). So there are only 5 + 25 unique placements of the second king once we place the first king on d4.


Why not 7.Bb4+ before playing Ne7 in the French Defence: Advance, Paulsen Attack?

Look at the stockfish lines after Nge7, or, Bd7, or a6. In all of them, black play Na5-b3 sooner or later, and for that the knight on b3 needs the queen's support. In that regard, Bb4+ is really not helping after, say, white plays Nc3 and the bishop on b4 blocks the queen from controlling the b3 square. Apparently Stockfish likes the Na5-b3 maneuver so much that anything else is inferior here.
Actually, a4 is just terrible, so black should easily equalize here with or without Bb4 (from a French player perspective).


Can a 2000 ELO rated player teach me middlegame play properly?

Is his rating a limitation to teach me?

No.
As I say in this answer, "you are too fixated on rating". High rating does not guarantee coaching ability. Low rating does not preclude coaching ability.
Today the guy in our club who does the most coaching is rated about 1900. 50 years ago, the first time we played for the same club, he was rated about 2150. He has coached a surprisingly large number of the players in our region who are now rated 2100-2300, although they moved on to better high level coaches before they got to those levels.
It is always interesting to watch him play one of his former students. Is the student going to give him a draw for old time's sake? Or crush him? If they give him a draw then afterwards the coach in him will tell them why they shouldn't do that while also saying "Thank you!"

I need lessons not only in openings and endgames but in middlegame play. Should I search for a better trainer out of my club or it is enough that this coach train me?

We don't know the trainer so we haven't a clue. Probably the best approach for you is to have a trial lesson and see what you think. Did you learn anything? Was it worth it?
Taking a trainer is not like getting married. If you find it is not helping you then you can just stop and walk away.


This is checkmate.

According to the fide rules (bold by me):

1.2
The objective of each player is to place the opponent’s king ‘under attack’ in such a way that the opponent has no legal move. The player who achieves this goal is said to have ‘checkmated’ the opponent’s king and to have won the game. Leaving one’s own king under attack, exposing one’s own king to attack and also ’capturing’ the opponent’s king are not allowed. The opponent whose king has been checkmated has lost the game.

3.9
The king is said to be 'in check' if it is attacked by one or more of the opponent's pieces, even if such pieces are constrained from moving to that square because they would then leave or place their own king in check. No piece can be moved that will either expose the king of the same colour to check or leave that king in check.


Best practical chances after g5 forking knight and bishop

Disclaimer :  in any case you are lost if your opponent plays reasonnably enough.

Assuming that you don't want to resign at move 10, my suggestion would be to continue with 10.Bg3 gf4 11.Bf4. Black's king is slightly weakened, you hit h6 and plan to continue with 0-0-0,f3,g4,h4,g5 to try and open his kingside as much as possible. In positions with opposite castles, material is not the single most important criteria, king security and initiative matter too.

If Black plays passively or conservatively, say 11...Kg7, then 12.f3 prevents Ne4, and with Bd3 and g4-g5 you may be able to muddy waters enough to induce later mistakes by Black.

If he plays actively and purposefully, with 11...Ne4 (or even 10...Ne4) 12.Qd3 e5!, not worrying about the Ph6 and intending ...Bf5, well, you hardly have anything to hope for...


Is there a specific penalty for intentionally damaging chess pieces or the board?

First of all I would consider the Preface:

  The Laws of Chess cannot cover all possible situations that may arise
  during a game, nor can they regulate all administrative questions.
  Where cases are not precisely regulated by an Article of the Laws, it
  should be possible to reach a correct decision by studying analogous
  situations which are regulated in the Laws.

I think it should be obvious that the sort of behavior you describe is wrong even if there is no rule that explicitly says "biting, drooling on, or cracking pieces is not allowed". :-)

But you can also consider

  11.5. It is forbidden to distract or annoy the opponent in any manner whatsoever [...]

I don't think any arbiter would question your claim of being annoyed if your opponent is chewing on the pieces!


Why is 14..Qd8 the most popular move in this variation of the Caro Kann?

This is ctg format property, or bug, if you like. There were no games played with 14.Bf4 and as well there were no games played with 14...Qd8. The ctg tree just knows position after 14...Qd8. Certainly it happens via different move order. So in 196 games wasn't played 14...Qd8, but 196 games saw the position arising after 14...Qd8.

This position arises in 11...Bb4+ 12.c3 Be7 line after move 12.

I dislike this ctg thing as it can hide a lot of refutations in move order sensitive lines. It navigates you towards most played positions, it doesn't show you the most played moves.


CNN autoencoder for feature extraction for a chess position

I'm very late but I am working on something similar. Here are are a couple of resources that involve using autoencoders.

https://chessvschessproject.wordpress.com/

https://arxiv.org/abs/1711.09667

https://github.com/oripress/DeepChess
Hope they help! Let me know how it goes.


I just checked three of the major sites: Chess.com, Chess24.com, and Lichess.com, and none of them seem to support this.

This is close, but not just online, but The Internet Chess Club, aka ICC, lets you do this, but only using the newest client, "ICC for Windows".

Here are the instructions.

And here is a screenshot.


What rule changes are proposed to minimize the incentive to draw a game?

Tried systems are to award 3 points for a win and 1 for a draw, not being able to offer a draw before move 30, and only being able to draw with the consent of the arbiter.  There has been a long discussion about giving black 0.6 points versus white's 0.4, due the the advantage of the first move.  There is also Fischer's suggestion of not counting draws in matches.

I have suggested on splitting the point in a ratio derived by the difference in rating.  For people with <= 75 points difference, the point is split evenly.  75-150, the point is split 0.6-0.4, weaker and stronger player respectively.  There could also be a variance based upon which color was played.  This should give the stronger player more incentive to play for a win, however it also gives the weaker player more reward for playing for the draw.


Stockfish evaluation of a position from PGN

Yes there are easy ways to do this. I'm going to briefly show you one quick way of doing it in python, using the python-chess module.
If the in-code comments are not enough, feel free to ask for clarifications or possible extensions of the code:

To showcase a working example, I've taken a game between Adams and Kasparov, you can download the PGN from the hyperlink. And our engine is the latest Stockfish available taken from the official website.

Lets call it PGNeval.py:

import chess
import chess.uci
import chess.pgn
import sys

arguments = sys.argv
pgnfilename = str(arguments[1])

#Read pgn file:
with open(pgnfilename) as f:
    game = chess.pgn.read_game(f)

#Go to the end of the game and create a chess.Board() from it:
game = game.end()
board = game.board()

#So if you want, here's also your PGN to FEN conversion:
print 'FEN of the last position of the game: ', board.fen()

#or if you want to loop over all game nodes:
#while not game.is_end():
    #node = game.variations[0]
    #board = game.board() #print the board if you want, to make sure
    #game = node

#Now we have our board ready, load your engine:
handler = chess.uci.InfoHandler()
engine = chess.uci.popen_engine('...\stockfish_8_x64') #give correct address of your engine here
engine.info_handlers.append(handler)

#give your position to the engine:
engine.position(board)

#Set your evaluation time, in ms:
evaltime = 5000 #so 5 seconds
evaluation = engine.go(movetime=evaltime)

#print best move, evaluation and mainline:
print 'best move: ', board.san(evaluation[0])
print 'evaluation value: ', handler.info["score"][1].cp/100.0
print 'Corresponding line: ', board.variation_san(handler.info["pv"][1])

Lets test it with the aformentioned game PGN, our command is:

python PGNeval.py adams_kasparov_2005.pgn

And here's the output I get:

FEN of the last position of the game:  br3r2/5ppk/p2pp3/4b1BP/N3P3/q4P2/1PnQB3/1K4RR w - - 4 27
best move:  Qxc2
evaluation value:  -10.87
Corresponding line:  27. Qxc2 Rfc8


Where can I get a nice set for Capablanca chess?

I'm recording this answer here because it took me quite a bit of searching to find something, primarily because I never found any sets going under the actual name "Capablanca chess." I did find workable sets under the names "Gothic chess" (apparently because of someone's fairly recent spin-off of Capablanca chess) and "Grand chess" (intended for a 10 x 10 board, see below).

I've only managed to find one 10 x 8 board, this one from House of Staunton. In addition, they have a full set of pieces (including pieces designed to be archbishops and chancellors, with a 3.75" king height) designed to fit the board, so that's at least a working answer to the question. Unfortunately, that piece set runs $200, so an alternative would be nice.

MindSports in the Netherlands has a set of pieces, which they intend for a game they call Grand chess that's to be played on a 10 x 10 board, that would work as a Capablanca chess set; the design of the archbishops and chancellors even reflect their movements, as can be seen in this picture (f- and g-files):

That set costs a more reasonable $40, but features a 3" king, and so that set would unfortunately be out of proportion on the only 10 x 8 board I've found (the one above). If you're happy to use a 10 x 10 board (and ignore part of it for Capablanca chess), then this is one way to go.

From what I know now, the best alternative to the $200 set above for use on the 10 x 8 board would be the House of Staunton's plastic piece set for Seirawan chess. This set runs only $40, has a 3.75" king height, and has a Hawk and Elephant piece for each side,

which can be used to represent the chancellors and archbishops of Capablanca chess.


Artificially isolated pawn in the Caro-Kann

The shortest explanation I can think of: if you play 1.e4 and 2.e5, presumably you want that pawn there for a reason. If you then immediately trade it off, you've lost whatever you were trying to achieve, like maybe space or central control.

In the case with ...c5-c4 followed by b2-b3: again presumably you want that pawn to be there for some reason (queenside space?). If instead you allow simply cxb3 axb3, then:

You don't have your pawn anymore
White has got rid of his a-pawn in return, rook pawns are least valuable pawns (can only capture one direction)
White has freed his a1 rook
White still has a single groups of pawns, while yours are split in the a/b pawn "island" and the c/d/e/f/g/h "island".

By adding ...b5/a4/a6/axb5/axb5/bxc4/bxc4 black also frees his rook and gets rid of the a and b pawns that could otherwise become weak later. And the c-pawn that you presumably wanted on c4 to gain space is still there.

However, I disagree that 3.exd6 is bad. White doesn't have good options there. After 1.e4 c6, 2.e5 is a bad move. It can't be maintained there and it doesn't help with the main goals in the opening (development, control of the center, and preventing the other side from achieving those).


Searching for a "where is the black king" problem

What leaps to mind is Raymond Smullyan's problem, and it's to find the White king but possibly it. A retro classic (and one of the few good ones he made.)
8/8/8/1r1b4/B7/8/8/3k4 w - - 0 1

(1+3) Where is the white king?
(Raymond Smullyan, Manchester Guardian, 1957)


What's the best strategy against the Hippo?

In my opinion, against these openings, the best strategy is to maintain the tension. Move around your pieces building up threats, and prevent the opponent's pawn breaks. Against these positions usually there is no forced win, but it is very hard to play them because of the cramped position, so your opponent will sooner or later make some mistake, and then his/her position will collapse.


Your approach is correct. Stockfish does it as well.

  https://github.com/official-stockfish/Stockfish/blob/master/src/search.cpp

if (rootMoves.empty())
{
  rootMoves.emplace_back(MOVE_NONE);
  sync_cout << "info depth 0 score "
            << UCI::value(rootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
            << sync_endl;
 }

There shouldn't be much penalty in performance, because:

You will always need to generate candidate moves anyway
Your code should maintain a bitboard (or other data structure) for the pieces checking the king. You will always need this information in your evaluation.

Consequently, what you're doing is just checking information that you already have.


Benko's three-mover that stumped Fischer

You can find this chess problem

[FEN "8/8/8/8/4k3/8/8/2BQKB2 w - - 0 1"]

on page 582 of Pal Benko's book "My Life, Games and Compositions" 2003 ISBN:1-890085-08-1 which also states it was first published in "Chess life" in 1968, so ChessBase is correct.


Where can I find this game with a sacrifice followed by a long series of checks leading to a discovered mate?

I believe that the game you speak of is the extremely famous Lasker-Thomas match in which Lasker forces Black to accept his queen "sacrifice" on move 11. It is followed by a king hunt in which Black's king is forced to the last rank by White, who then finishes the game with the king giving a discovered check from the unmoved a8 rook. The game is notable because White could have chosen the exemplary move 18. 0-0-0#, which is exemplary because castling while also delivering checkmate has been a rare achievement in chess history, but Lasker instead chose the more mundane, in my opinion at the least, 18. Kd2#.
The checking sequence isn't quite 10-11 moves long, but otherwise it fits the bill perfectly, especially with the particular mating move that you described.
[Title "Edward Lasker-George Alan Thomas, London England, 10/29/1912"]
[FEN ""]
[startply "20"]

1. d4 e6 2. Nf3 f5 3. Nc3 Nf6 4. Bg5 Be7 5. Bxf6 Bxf6 6. e4 fxe4 7. Nxe4 b6 8. Ne5 O-O 9. Bd3 Bb7 10. Qh5 Qe7 11. Qxh7+ Kxh7 12. Nxf6+ Kh6 13. Neg4+ Kg5 14. h4+ Kf4 15. g3+ Kf3 16. Be2+ Kg2 17. Rh2+ Kg1 18. Kd2#


[FEN "8/2R5/1B1k4/2R5/3N4/1K6/3p4/8 w - - 0 1"]

1.Kc4 d1=Q 2.Rd5#

So two moves, not three.

The first thing to note is that the Black King cannot move.  The second thing to note is that (most) non-forcing moves by White will allow Black to Queen the pawn - with check.  This fails the challenge.

Experimentation will show that moving the Rook on c7  (for example R7c6+) allows the King to escape to d7 or e7. The other frcing move is Rd7+ but of course that isn't helpful.  Since the c7 Rook is protected by the Bishop, we can try moving the other Rook.  We have to find forcing moves, so the first one I see is R5c6+. But this lets the King escape to d5 or e5.  Another forcing move is Rd5+ but the Black King would eat it. But it's so close to checkmate.  There's no forcing move with the Bishop.  The Knight has 2 forcing moves, but neither seems to help.

So we move the White King to c4 to support the Rook we intend to put on d5.  This has the additional benefit of not costing us a tempo if Black queens the pawn.  That realization is fundamental here.  The White Knight blocks the Queen from capturing the Rook on d5.


Matrix representation of piece position for a chess engine

This is a very common data-structure in chess engine - Piece-Square-Tables.

Refer to
https://chessprogramming.wikispaces.com/Piece-Square+Tables for more details.

Basically, it gives a score for a piece on a particular score and it's almost always symmetry (white and black have the same score but flipped).

For example, if I modified the score for knight in the table on d4 to positive infinity. The engine will believe placing a knight is very important, it'll sacrifice it's queen, rooks, bishops just to permanently position a knight on the d4 square.

The values are usually determined by trials-and-errors. Stronger engines such as Stockfish learn the values by playing hundreds or thousands of games, this is known as parameter calibration or automatic tuning.

Refer to https://chessprogramming.wikispaces.com/Automated+Tuning for more details.

CLOP and Texel are two common tuning methods.


Is it ethical to refer to opening book for the first few moves of a correspondence game?

Yes.

ICCF: Says nothing about it, or assistance of any kind, and you can even use computers legally. Here are their rules.

USCF: "3. You may consult chess books and periodicals but not other players." Here are their rules.

With regards to the ICCF rules, my guess is that they just decided it was too hard to police computer used, so they just allow it. Books have always been permitted.


As it stands now, your post will be marked as duplicate, so I will answer fast before it is closed.

  Can you suggest me an opening that is easy to learn and is suitable for a beginner like me?

This is very hard to do, because your opponent will always have chance to play the move that transposes into different opening. Studying seriously openings will limit your development because you don't know which style suits you. That should be your main goal -> to "discover" your style, to find out what suits you and what not.

To achieve this, you need to learn basic endgames first, tactics second and then typical middlegame positions.

At your level of skill, you just need to survive the opening relying on general opening principles. Your goal will be to leave the opening with equal position.

Just play any opening that you find interesting, and experiment. Try them all out, don't be afraid! Once you find out which opening suits you, ask a question about it here and we shall further help you.

This was the best thing I ever did when I was a beginner! I found a partner that was way stronger than me, but was willing to teach me by playing with me. I tried all sorts of openings against him until I found those that I had "natural gift" for. Maybe you have talent for closed openings or open games, but you will find that out only by trying out different openings.

So remember:

Learn basic opening principles!
Play everything, there is enough online documentation on any opening for a beginner level ( ask here for help if you get stuck )!
Work very hard on tactics!

For now, this is enough. Once you feel confident in your skills ( once you estimate that you have improved enough for intermediate level ) come back here and ask us for further advice.

Good luck, young grasshopper! :)


Many responses will be good against g3 - if you have problems against it  - actually its indicator that you have problems with general chess principles, so just study chess, get some good book on middle-game strategy and don't think of g3 for now. g3 is very slow and has no real opening threat for black - it takes on middle-game understanding though.


Why isn't Bird's Opening at least as popular as the Dutch Defence?

A good opening for Black seldom is a great choice for White even with a tempo up. Grandmaster Alex Yermolinsky discusses reasons for this in his book "The Road to Chess Improvement". One of the main reasons is that the opening goals are not the same for both sides in the opening, and schemes that are suitable for defense or counterattack are much less valuable for assuming the initiative.

Famously, when grandmaster Vladimir Malaniuk, a great proponent of the Dutch Leningrad with Black, had some issues with his White repertoire, someone suggested to him that he should start with 1.f4. His retort was definitive:

  That extra move's gonna' hurt me!

As a side note, the Dutch is not that popular, especially at the highest level.


What was Fischer's preparation for tournaments?

This is a question for people who knew him well personally. Anyway Fischer lived and breathed chess almost daily since the day in which he learnt the rules, until well into the first match vs. Spassky, so we have no reasons to believe that he changed his lifestyle before tournaments, i.e. he constantly played and studied chess, at least until his life's main mission changed and became the one to "unmask the Jewish conspiracy". But this happened after the first match vs. Spassky. However it is evident that the mature Fischer was aware of the importance of being fit physically, so we have to suppose that he did some exercise, especially before important matches and tournaments.


I am not a good bullet player, but will try to answer anyway. Apart from the usual suggestions (studying the game and working on tactics) the following ideas come to mind:

In short time controls whose typicall completely neglected "non functional" aspects
of chess can become more important, like time management, dealing
with risk, dealing with hopeless positions, flagging and avoiding
getting flagged. Observe a few videos of Nakamura or any other chess
hero of your choice playing banter blitz/bullet, dealing with all of
that. This has helped me a lot.

In bullet flagging and getting flagged is integral part of the game.
Get conscious of it. Whose who don't like that, should simply play other formats.
E.g. if you are short of time you cannot afford
to exchange into an lengthy endgame, since your opponent will simply
start to flag you.

Since time is short, all chess features which needs comparative more
time to handle are affected negatively, at least this is what I
firmly believe (I can not a good bullet player, since I have no real
feeling for this problems). King safety gets much, much more
important. The knight gets stronger in the endgame and can become
extremly strong in the late endgame. Even the tinyiest advantages
are usuall converted, if they can be exploited long enough.

Bringing the opponent out of his comfort zone is always helpful, in
bullet it can be deadly on the spot. E.g. against the Kings Indian
attack (Nf3, g3, Bg2, 0-0) Nakamura plays sometimes in bullet d6,
Nf6, Bd7, Qc8, Bh3 and then h5 with mating attack. I copied it and it
scored deadly for me ;-).


Chuzhakin's System Hazardous Elements and Rules

I googled the name of the file, chuzhakinssystem.pdf, and found a copy here: https://docplayer.net/22332201-Chuzhakin-s-system-version-2-14.html

Better yet, it can be found using the Internet Archive's Wayback Machine: https://web.archive.org/web/20180219185540/https://neoneuro.com/downloads/chuzhakinssystem.pdf . I think this link is more likely to be stable.


These questions of rating inflation/deflation over time are very tricky to answer objectively. It is very easy to find mid-range players who will say something like "My rating today is about 200 points lower than it was 10 years ago but I'm just as strong if not stronger [spot the wishful thinking] therefore there must have been rating deflation at my level during this period". Full disclosure: I'm one of those mid range players :-)

To get more objective views (I think definitive answers are another, more complicated, matter) you have to look at how many players were above a given level today and 10 years ago and perhaps also the percentage of players who were above a given level today and 10 years ago.

That data is available via the FIDE rating website where it is possible to download rating data going back to 2001.

Here are the figures from the January 2019 and January 2009 lists:

January 2019
Players rated above 2650 = 109 (0.0335%)
Players rated above 2100 = 40940 (12.6%)
Players rated above 1500 = 224873 (69.1%)
Total rated players = 325306

January 2009
Players rated above 2650 = 75 (0.0756%)
Players rated above 2100 = 40044 (40.35%)
Players rated above 1500 = 98669 (99.4%)
Total rated players = 99232

Interpreting these figures is difficult, particularly the percentage ones.

If you just look at absolute values then there are a lot more players graded over 2650 today than 10 years ago and the same for players rated over 1500. This suggests rating inflation at both levels. I've also included values for players over 2100 because, intriguingly, these are almost unchanged.

If you look at percentage values then a much smaller percentage of players are rated over 2650 today than 10 years ago and the same for players rated over 1500. This would suggest  a great deal of rating deflation at both 1500 and 2650 levels. The deflation is highest, however, at the 2100 level (out of the three levels I have looked at).

However, I think the percentage values are problematic. First if you look at the 1500 level 10 years ago there are only 563 players with ratings <= 1500. I suspect that this is because the only FIDE rated tournaments for players below 1500 were tournaments like continental and world junior tournaments going down to levels as low as 1001.

By the way, the first player I can find to have had a rating just above 1500 was the Polish player Sebastian Kobus. His first rating was 1500 in January 2006. For 1000 it was Indian player Hakeem Nikhil with a rating of 1003 in September 2012. The first sub 1300 player was French player Michel Khechab with a rating of 1260 in September 2009.

There were, of course, a lot of players playing tournament chess whose strength was below 1500 but they were all playing nationally graded chess because there simply were no FIDE rated tournaments for players that weak outside the big FIDE championship tournaments. Those figures show that today over 30% of players have a FIDE rating of 1500 or below compared to just 0.6% 10 years ago.

My tentative conclusion is that there has been some rating inflation at the level of 2650 and above because there has been a 45% increase in the number of players rated over 2650 which I think cannot be accounted for by increasing number of chess players.

I think there has been a lot of deflation in higher mid-ranges (typified by the 2100 figures) because there has been some increase in chess playing numbers which is not reflected in higher numbers at these levels.

At the lower mid-range (1500) I think the data is unreliable 10 years ago due to the very small number of tournaments open to players of these levels and so it isn't possible to draw any conclusions about this level.

Regarding the data for players at the 2100 and 2650 levels I think this is reliable because I think FIDE rated tournaments were capturing most players at these levels.


Understanding the Tarrasch defence to the Queen's gambit

What is the idea behind 4... c5?

Basically the same ideas as behind playing c4 in the Queen's gambit:

challenging the center,
potentially exchanging the c-pawn for a valuable central pawn,
opening the c file for a rook,
giving the knight a square on c6 (which is often a better square for the knight if the pawn has moved to c5 already)
potentially threatening to leave white with an isolated queen pawn (see below)

  Why form a hostile bloc of two black against two white pawns on the c and d files?

Why not? "Hostility" is not something you should be afraid of when playing chess.

  Once the bloc is formed, how does one decide whether ...

There is no strict rule here and various captures and no-captures have been tried and tested by good players. A typical motive you need to be aware of in these positions is the isolated queen pawn (IQP), i.e. a player might be left with a pawn on the d-file and without any pawns on the c and e files which could support it.

An IQP leads to somewhat asymmetric play, with one player trying to block and put pressure on this potentially weak pawn, while the other player (the one with the IQP) is trying to take advantage of his better piece play that is a result of the pawn structure and also has ideas related to advancing the IQP.

If there is no IQP on either side, the positions resulting from this opening are often very symmetric, potentially boring, and it is difficult to find a good plan in them.

So I'd say the decision on how to capture is basically determined by what kind of game you want:

with an IQP; asymmetric, unbalanced game with clear plans for both sides
without an IQP; symmetric, equal position, with unclear plans


I don't think FIDE would be involved in regulating such events because they are not rated.
I found this interesting PDF with some notes, although I think they could be improved. For example, it is not clear if the player loses the game after three passes.

The exhibitor plays the white pieces on each board.
Do not touch any chessman until the exhibitor arrives at your board. When the exhibitor is standing in front of your board, make your move (within 5 seconds) while the exhibitor is observing. The exhibitor will make a move on your board before going on to the next board.
Participants, but not the exhibitor, must abide by the touch move rule. The exhibitor’s move is not final until he or she touches a piece on the next board.
Each player is allowed three passes when the exhibitor arrives at his or her board. Using a pass means that the exhibitor will skip your board, but you will need to make a move (or use another pass) when the exhibitor comes back after visiting the other boards.
Participants may not receive assistance from other players or bystanders during their games.
Exception: participants may sign up as a pair and play on one board.
Participants must take notation.
If the exhibitor has any other rules, those will be announced at the start of the exhibition.

Source:

Simul Rules


Why and when should one make a zwischenzug (in-between move)?

That's really an enormously broad question. The answer is "because it's a good move, sometimes." :-)

Let's say one player expects the game to go "I take here, then he takes there, I take there, he takes there, I take back the rook... and I end up a pawn up."

What happens is "I take here, he takes there, I take there, he moves the rook with check, I have to move my king, he takes there, I can't take back the rook... and I end up a rook down."

That's the sort of situation where a zwischenzug helps. When what at first looks like a forced sequence of moves can actually have an extra move added to the middle of it that makes the end result better for the side doing it.

Turning this into some actual position with a diagram and such is left as an exercise for the reader.


No writing down moves in advance of making, or in advance of completing

Once a move has been made (hand has left the piece) the move cannot be changed unless it is an illegal move.

The rule against writing the move down in advance is in relation to "taking notes". If this were allowed you could write down what you thought was the best move and then stop and think for another 10 minutes considering other possibilities. If you reject the other possibilities you don't have to worry about forgetting your original choice because you wrote it down. If half way through you see a better move than your original you can erase the original move and write the new move and continue thinking. It is this behaviour that the rule is aimed at stopping.

In the case you saw the question does not arise because having made the move the player can't change the move. Writing the move down now whether it is before or after pressing the clock is not taking notes and is not against the rule. If the arbiter really thought his behaviour was against the rule and gave a warning then he was wrong.

I am a FIDE arbiter for an Asian country, currently living in Europe.


Chess challenge from a newspaper in 1927 (win in 2 moves)

Ask yourself: what would Black do if he were to move? After 1... Kc7, 2. Bxe5 is mate. His other option is 1... c5, threatening to escape with 2... Kc6.

The solution:

   1. Nc5! blocks the c-pawn. Black gets the additional option of 1... Kxc5, but after that, 2. Ne4 is mate.

(I can post an interactive version, but that doesn't work with spoilers. And it's a good visualization exercise.)


What is the best move for black in this game?

The knight on h5 is pinned to a rook, and faced with the potential threat of g4. To unpin this knight, Black should play Rh7, so that the knight is free to go to f6 (where it will protect the rook).

[FEN "1k5r/p1p2pq1/2n5/1p1p3n/1P1Pp2Q/P1P1P1P1/1B1K2B1/7R b - - 0 1"]

1...Rh7 2.g4 { This move is just for illustration, and probably not best. } Nf6

I would argue that Rh7 is the best move in this position. It has been stated in a comment that Stockfish marginally prefers a6 to Rh7 (although it always prefers Rh7 when I try it, at all depths from 3 to 46 - it probably depends on cache state, number of threads, etc.). But from a human point of view, I don’t think a6 makes much sense: all the while the pin exists, White can try to find ways of exploiting it; Black ought to put a stop to this right now. In fact, the main purpose of a6 (from Stockfish’s point of view) seems to be to deal with one possible way of exploiting the pin; but clearly it’s simpler just to remove the pin.


There is something to be said for choosing mainlines from the get-go. I heard several strong players (for example Jan Gustafsson, Judith Polgar) say, that they wasted time by playing sidelines in their youth or that they had problems to master certain openings they had avoided for too long. (Gustafsson played 1…g6 and Polgar King's Gambit).

So if you are young and very ambitious it makes a lot of sense to go for openings you will never have to discard. If you look at the absolute top, even Carlsen's experiments with sidelines quite often completely backfire (Northsea Defense vs Adams, Pirc vs Naiditsch, Leningrad Dutch vs Wojtacek, weird gambit vs Saric, etc.).

But most of us never reach these heights and under Elo 2400 you can get away with all kinds of openings. So my choice is to play what I feel comfortable playing and from time to time mix in some completely new stuff so I don't get bored. I play some very shaky and borderline incorrect stuff, but I can't remember ever losing because my opponent just played "the refutation". There are always chances.


What are the essentials of chess etiquette in a serious, over-the-board tournament game?

First of all, be quiet and don't talk. You can whisper, but it is still considered rude / impolite.

If the round begins at 9AM, be there punctually. In some tournaments you might even lose the game if you're not there within the first 30 minutes.

If the game begins, you can say something like 'I wish us a good game', 'Good Game' and so on.

If something happens on the board and you don't know what to do, you can ask the referee or try to fix it with your opponent.

What is the proper way to ask for a draw?

If there is a big chess game of two big chess players and you want to watch it, don't stand right next to them. Let them have their space. video

If you write your moves down on a piece of paper and you have to give it to the tournament administration, be aware that the result is the same on your slip + the opponent's slip. Both slips also have to be signed by both players.

No smart / cell phones are not allowed during your game (you need to turn them off) and it it also not allowed to turn them on if you watch some games, but you're not playing. The reason is, you could be cheating and some crap like that.

If you want, you can ask your opponent to analyze the game, after it is over.

If you have any further question, just ask.

EDIT:

When you are giving a Check, don't say it. Thanks Akavall

It's also considered poor behavior to eat at the board. Thanks Andrew Ng Of course, you can drink some water or something else, but be aware with the space. Normally the desks aren't that big.


How could I have won this Q vs R+N endgame?

Partial answer - a Nalimov tablebase says your queen sacrifice should have resulted in a draw.  Black cannot withstand your pawnroller and goes for a perpetual/stalemate combo. Your fatal mistake was 9. Kf5

[FEN "6k1/r7/5PKP/6P1/8/8/8/8 w - - 0 9"]

1.Kh5 (1.Kf5??) Kh7 2.g6 Kh8 3.f7 Ra5+ 4.Kh4 Rh5+

From the starting position, Stockfish recommended...

[FEN "8/2k1r1p1/5n2/5PK1/6PP/3Q4/8/8 w - - 0 46"]

1.Kg6 Nd7 (1... Nxg4?? 2.Qc4+ {Black can't hold the g-pawn and both white pawns will queen... it's a merciful mate in 17}) 2.Qc3+ Kd8 3.Qa5+ Kc8 4.g5 Ne5+ 5.Kh5 Nd7 {This shuffling moves shows that Black is out of ideas.} 6.f6 gxf6 7.Qc3+ Kd8 8.gxf6 Re4 9.Kg5 Re6 10.Kg6 Ra6 {Black could take the pawn, trading both his pieces for the Queen and a pawn. But then White Queens the h pawn. } 11.h5 Ra4 12.Kg5 Ra2 13.h6 Rg2+ 14.Kf5 Rh2 15.Kg6 Rg2+ 16.Kf7 Rh2 17.Qa5+ Kc8 18.Ke7 Nb8 19.Qf5+ Kb7 20.Qb5+ Ka7 21.f7 Na6 22.f8=Q Rc2 23.Qf6 Rc7+

Yep, that's pretty computer-tactical. But what you see is White pushing the King away from the pawns, and then relentlessly pushing the pawns. As an aside, it would take quite a player to separate their King from the Rook without losing the Rook to a queen tactic. Not recommended!

Here's what Stockfish thinks about the sacrifice.

[FEN "8/2k1r1p1/5n2/5PK1/6PP/3Q4/8/8 w - - 0 46"]

1.Qc3+ Kd8 2.Qxf6 gxf6+ 3.Kxf6 Re4 4.h5 Rxg4 5.h6 Rg1 6.h7 Rh1 7.Kg7 Rg1+ 8.Kf6 {Draw by repetition.} )


Triple check is impossible, unless you want to count an x-ray attack as the third check.  A queen and rook attacking on the same file is normally thought to be one check.


Would a professional level player put their queen in danger of capture from the opposing queen with protection?

You're referring to a queen trade, and yes, there're plenty of situations in which you want to trade queens. In general, trading queens simplifies the position, which is good if:

You're up material. The fewer pieces there are on the board, the harder it is for the opponent to cook up counterplay.
You're on the defensive. The fewer pieces there are on the board, the harder it is to launch a successful attack on the enemy king.
You have some kind of advantage that makes you win the endgame, e.g. fewer pawn islands (this is a technical chess concept that measures on how many separated pawns you have), an outside passed pawn, and so on.
Various other reasons (there are a ton of them).

Here's an example from the recent game Topalov-Maxime Vachier Lagrave.

1kr5/1r3p2/2np3p/p5p1/2P3P1/PPNq4/K1R3QP/7B w - - 0 39

Black has just played Qe3-d3, and it's White's turn. It should be clear that Black's queen is much stronger than White's right now: it's much more aggressively positioned and it's generating a lot of threats. So Topalov played 39. Qd2, offering the trade. MVL promptly played 39...Qxd2, because if he didn't, White would play Qxd6+, eating a pawn for free.

This kind of exchange happens all the time at top level.


What are the biggest free chess databases? Is it legal to download games from them?

FICS database

Lichess database

Million base 2.2

PGNMentor

Is it possible to use this information for my own purposes

Absolutely! Nobody has the copyright. Enjoy your machine learning adventure!


Blender 3D models for chess pieces and board for blind players (open licence)?

I don't know much about 3d printing, but you could design your own.

Windows has a program called 3D Builder with a built in chess set that you modify, as well as a 4x4 game board that can be modified and built up. 3D Builder is free on the app store.

If you get stuck, I suggest visiting 3D Printing.SE.


Why did Black allow White to capture en passant two times in a row?

The point was to win the queen. Yes, White gets two passed pawns, but a passed pawn won't necessarily get to be promoted.

Sure it happened in the game, but that's not really the point here.


Automatically annotating the beginning of my games

As far as I know, all the tools available today offer an opening book (tree) that has to be traversed manually by clicking yourself forwards and backwards in the book. To evaluate the position at every point of the opening, you can have an engine running and combine this with the statistics that are included in the opening book for white win / draw / black win. Relatively recently, Chessbase Online entered the stage. Let's not forget about Chess dot com and Chess 365 who also offer online books. So instead of having a software installed on your computer, you can use these online services to check and evaluate your openings.

Additionally, you could consider posting opening related questions here on Chess SE and get some valuable insights...!


I play a lot of board games and a lot of chess in particular. I can tell you that every chess player has a certain element of nervous energy whilst playing. This keeps us sharp. These are the reasons I believe chess generates nervous energy in the players:

Competitiveness: Chess is purely competitive and we are all playing to win on some level, whether it is to beat the opponent, get a draw against a Grand Master, or to improve our game, i.e. beat ourselves
Skill: There is no random component. I can't blame the dice gods if I lose
Not a team game: Similar to how I can't blame the dice gods if I lose, I can't even blame my team mates! Even when chess is played as a team (e.g. Olympiad), what my team is doing during my game doesn't affect the outcome of my game
Ratings: This relates to pride, but if I am playing against someone who I see as being a weaker player (lower rating/child player/patzer), then I'll be extremely embarrassed to lose. Similarly, I want to beat higher rated players to inflate my ego


In general, a chess set has the king as the tallest piece, followed by queen, bishop, knight, rook and pawn in that order. Notice in the starting position how the piece height decreases smoothly from the centre to the edge. (Also, when buying a chess set, usually the height of the king is given as a guide to the size of the chessmen.)

Thus I would say the king is the taller of the two pieces, which from your picture looks to be the one with the spike on the left.

This ordering of height may not hold for particularly ornate decorative sets.

However, if you're not going to use the set to play against other people in tournaments (where usually Staunton pieces are mandated anyway), the correct answer would probably be: the king is whichever piece you think it is.


My question is about inconsistencies in Stockfish 7 outputs

Many expert chess engine users (such as correspondence chess masters) advocate using more than one engine to analyze a position, because each has strengths and weaknesses.

Generally, Stockfish is considered strongest in positions with tactical elements, while Komodo is biased toward positional / strategic strengths.  Neither is a broad-spectrum solution.

As other responders have indicated, there's a lot of squishiness in the output of engines when there aren't any forcing lines, or transpositions are possible and undifferentiated.  Engines do a fair amount of pruning, which saves computation but introduces problems with "horizon". The horizon is the depth of moves the engine will look at a variation that leads to a disadvantage. Such a variation may have a redeeming comeback move at the end, but may be just long enough that the engine gives up analyzing the line before it reaches the comeback move, because it's over the horizon.

On its way to a "final" evaluation, the engine is essentially approximating.  That is, it evaluates the position, adds a few more moves and looks at the position, evaluates for the "best" move based on those, shifts to the next position, adds a few more hypothetical moves and evaluates, shifts, and so on.

At any one particular instant, the engine may be just about to shift from one evaluation of the position to another, even while the depth you're specifying is being reached.  If you terminate the analysis manually (i.e. pick a move and make it, or just hit the Stop button), you may get a different "best" move recommendation in one millisecond, and another one a millisecond later, even at the so-called maximum depth.

The best way to ensure consistency is to run the engine by itself in analysis mode using software such as Fritz.  The engine will evaluate the actual moves of a game (or an opening variation) offering improvements. The computation behind the improvements will be strictly limited by depth or time, as you specify.  If you let the engine terminate the search at each position, you should get consistent (deterministic) results. Unfortunately, although it will annotate the improved variation at each position, this approach involves the engine resetting its analysis with each move/position of the move score that is analyzed.  It won't move from improvement to improvement to improvement, leaving the game behind.

To get that kind of result, you need an engine tournament.  Give two identical engines a starting position (such as the Berlin or Moscow Variations of the Ruy Lopez) that you want to improve from, set their limits as discussed, and let them duke it out. Play at least a dozen games, and see if anything shakes out.  Two cautions:

This is time-consuming (but at least it's not your time), and
As you go further and further from known theory, the less likely that you'll ever see that position in an actual game played by anyone other than these engines, for the reasons discussed above.

BTW: As far as I know (and my research supports this), non-deterministic algorithms are not used in Stockfish or any other major engine.  The reasons for this are self-evident - if you're looking for a solution to a deterministic problem, you use a deterministic approach.  Stochastic approaches are only better in stochastic problem domains, or where a deterministic model is unavailable or problematic in itself.

As far as analysis depth goes, there's a point of diminishing returns that's determined by what you're trying to accomplish.

In different types of positions, the evaluation function of any engine will tend to stabilize at different points.  For one type of position, there will be no noticeable difference in the evaluation or the recommended "best" move after about 20 ply.  In another, you may need to hit 26 or 28 ply for the move to stop changing, and the evaluation function to stabilize at a terminal value to 2 significant digits (e.g. 1.87, instead of 1.86 or 1.88).

Clearly, if your goal is the perfect move / best evaluation accuracy, then if you can only choose one depth/time parameter limit, instead of a stability limit / sensitivity threshold, then you need one large enough to accommodate the most positions where the evaluation continues to be unstable to greater depth/for longer analysis time.  You need to aim high.

But there's a tradeoff.

In an actual game, as the game proceeds, the probability increases exponentially that one or both (human) players will play a non-optimal move.  Since the engine only calculates optimal moves, this means that in quiet positions (and in some complex tactical ones) the engine's choice of a move and the actual move played will almost always diverge, even if only slightly. It will also do so surprisingly frequently, often as many as a dozen times in a game even between GM's. This is, in fact, one of the indicators that TD's use to figure out whether a player at a tournament is getting outside help from an engine.

Because of this, if you're comparing a variation that an engine analyzes with a line that humans might actually play, the longer the variation, the more likely it is that the tail of the variation will only match the humans' moves when there is a forcing line.  In fact, unless the line is forcing, a fair amount of the time not even the opponent's first reply will match the engine's expected optimal reply.

The more unclear or quiet the position, the shorter the useful tail of an analyzed variation will be, even if the opponent replies with the expected move.

So, if you're analyzing a murky or quiet position or opening, and you're curious to know whether an engine could possibly play a line better, then have at it. But if you want to know if it's possible to find a single winning line given the replies that the opponent would actually end up playing, the real odds start to look like a craps game as the variation gets longer.

That said, there are ways to optimize how you use the calculation time as you analyze a game or an opening variation.

As @GeorgeJempty indicated, you can get much better results at 35 ply (ply are half-moves; 12 ply is 6 moves for each side) than you will at 25.  However, I use Stockfish on a Quad AMD at 2.9 GHz, and the positions where I need to go even 26 ply deep to find a hidden winning move that were missed at 25 ply are very few and far between (something on the order of 1 in 1,000).  For me, that's simply not worth the extra compute time it takes to find it.  What's more, the resulting improvement is almost certainly going to be negligible, because the probability that the opponent would have made the corresponding replies shrinks to zero, and the resulting end position would never appear.

In other words, the longer the move sequence, the greater the probability that any analysis will be overtaken by events.  This is one reason that even Grandmasters rarely calculate beyond 12 ply (except in endgames), and often only calculate to 4 or 6, relying on positional intuition instead.

As for how much of a difference ply depth makes at extreme depths, I have some background in the problem.  When I'm screening games for analysis targets (by this I mean trawling through large sets of them to find ones that had interesting highlights suggesting they're worth deeper analysis), I use just 23 ply. My configuration can get through about 10 games an hour at that clip, so I can process about 750 every night.  Once I find these, I then reset the depth to 25, and rerun the analysis on those selected games.

Obviously this approach would only make sense if I'd tested it, and I have. I've run a few experiments to test the merits of different depths, and the settings I use turn out to be optimal for the compute time I'm willing to allocate.  Only about 1 in 50 games turns out to have an interesting feature that shows up at 25 ply but gets missed at 23.  Clearly, that suggests that some of the games I screened out using 23 ply would also have shown such elusive features if they'd screened in instead, and subsequently been processed at 25 ply.  That's just the opportunity cost of the rate at which I choose to process games, and for my purposes, there's so much low-hanging fruit I don't really need to go climbing trees.

I would definitely take advantage of every CPU on your PC's chip, though. Most of the world's PC's computational power is incredibly underutilized.  On my configuration, at 1 CPU Stockfish does about 1K positions / sec, while at 4 CPU's, it runs over 4K positions / sec.  That quadrupling of the rate really tells when you're data mining, as I am.

To reiterate, I would also turn to Komodo for analyzing openings and quiet/murky positions as a comparative tool, and you should find that with one of the two engines the evaluations stabilize tolerably soon, at around 22-23 ply for most positions.


The main ideas behind d4 serve several purposes.

It threatens dxe5 winning material.
It opens up your pieces, like the Bc1, in particular.
It gains space since the trade on d4 leaves white with a pawn that is more central than black's d6 pawn.
And probably most important, and this is typical of many
double-king-pawn openings, and that is that it is easier to inhibit
black from playing the freeing d5 move. If he manages that move
soon, he has generally solved all his opening problems, and the two
center files will open up, and the major (heavy) pieces will be
traded.


How many queens can be on the board without neither forced mate nor forced stalemate (53?)?

57 Queens:

[FEN "QQQQQB1k/QQQQQ1bq/QQQQQQKB/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ/QQQQQQQQ b - - 0 1"]

(edited FEN, White to move).
(2edited, thanks Noam D. Elkies)


What are good Android apps to learn chess from scratch?

I would suggest LiChess. It is free (of charge and ads) and it has a website + android app. You can practice vs other opponents, solve tactic puzzles. They also have a learning section, where you can learn about simple strategic concepts.


I will try to answer this in a different manner, the way I understand this topic.
Do we think on every signal, turn, fork when we drive?
Do we think every time we eat food or walk on the street?
The answer is yes, we do, but that thought process has moved to our reflexes to the extent that our brain does not let us know that it is doing a task (Thankfully!) unless there is a critical alert in our brain that puts us to think about the situation.
Just as a fact, the human brain takes 35000 decisions per day and not every decision we are aware, but is still taken.
Just like this, the Grandmasters have reached a state where the rudimentary positions are into their reflexes and they effortlessly play their game, to the extent that they invent positions and theories on the board itself. Reaching that state is "mastery"


What are the disadvantages of delaying c7-c5 in QGA?

I was looking thoroughly for the omission of ...c5 in many repertoire books ( Semko & Sakaev-Queen's Gambit Declined 3rd ed., Iakov Neishtadt-The Queen's Gambit Accepted, James Rizzitano-How to beat d4,Raetsky & Chetverik-Starting Out The Queen's Gambit Accepted ) and found absolutely nothing about the pros and cons of delaying this move!

This is rather disappointing as the idea is quite reasonable, and can come to any player rated from 1800 up to 2400 so it should be explained in repertoire books. However, after trudging through the ECO D 1987 I was able to find something:

[Title "Black delays c5 break"]
[fen ""]

1.d4 d5 2.c4 dxc4 3.Nf3 Nf6 4.e3 e6 5.Bxc4 a6 ( 5...Be7 6.O-O O-O 7.Nc3 c5 ( 7...b6 8.Qe2 Bb7 9.e4 $16 ) 8.e4 cxd4 9.Nxd4 Qc7 10.Qe2+/= ) 6.O-O ( 6.Nc3 b5 7.Bd3 Bb7 8.O-O ( 8.Qc2 Nbd7 9.a4 b4 10.Ne4 c5 11.Nxf6+ Nxf6 12.dxc5 Qc7= ) 8...Nbd7 9.e4 b4 10.e5 bxc3 11.exf6+/= ) 6...b5 7.Bd3 Bb7 8.a4! b4 9.Qe2 Nbd7 10.e4 Be7 11.Nbd2 c5 12.e5 Nd5 13.Nc4 $16

In either case White can favorably open the game ( he will have more space and is better developed, also notice that his center is solid and your ...c5 will only free your game but will not give you sufficient counterplay ) and get good attacking chances.

In the main line in the above diagram, you seem to have solid position but do not be fooled. Yes, White has e5 square no more, but you are weak on the c-file since your b-pawn is on b4 where it does nothing useful. White was able to outplay Black by posting knight to c4, which is wonderful square for him. He can also attack on the kingside. Black on the other hand, has no viable counterplay and will probably have to weaken himself further with ...h6 at some point.

As for 6.Nc3 sub-line from the above, you can achieve typical position with isolated pawn after ...c5 at some point, but again White is just so superior in development and has typical space advantage. You lag in development, thus you will need time to organize counter-attack while White can already start creating problems to further delay you, like regrouping pieces for kingside atack.

As for 5...Be7 line, White also has superior development and wonderful centralization of his minor pieces. He has more space and his queen is well posted, unlike yours as she is prone to harassment with Nb5 ideas. You will need to play ...a6 at some point, further losing time which is dangerous if we take White's lead in development and space advantage into account. Black may get playable position but it will be a series of accurate moves and even then White will have at least small advantage.

It seems that this is the point of 5...c5, to ensure Black gets enough space in the center and hinder White from harmoniously developing his pieces, by forcing him to count on entering endgame or simplifications.

This is all I was able to find, if anyone has the latest ECO D I would highly appreciate the update on lines I listed above...

Hopefully this answer helped, as there is nothing else at this moment I can do. Best regards.


How would I know why a move is good or not?

As far as I know, there is no engine that does what you are looking for. An engine is a program that does nothing more than take certain positional and material elements into account, and gives it an evaluation. It does not break down the elements and show you how it evaluated each of them. Sometimes, it can be obvious because the analysis is a clear win of material, but most of chess is more deeply hidden than that....sometimes VERY deeply hidden.

I found a site that does what you are asking. It takes those evaluations, and tries to put words and understanding to the numbers.

You it on one of the problems with chess-analysis software for weaker players, and that is that it just shows the strongest move per the computer, without any explanation why. There are some programs, like the ChessBase programs that, using their "Tactical Analysis" feature, attempt to give some explanation to the moves, but they are all wanting.

That said, decodechess.com seems to do better than most for newbies. As a USCF Master, the explanations are pretty good from what I can see, and the underlying "engine" is the same Stockfish that you use. Although a premium account is $99/year (right now, 50% off with the promo code "getserious". for the record, I have no affiliation with the site, nor am I a member), you can create an account, and "decode", or analyze three games per day for free. If you like it, I would jump on the promo.


Here is the solution:

   1.Rh1 d4 2.Ra1 d3 3.Ra3 bxa3+ 4.Ka1 a2 5.Ba3 Kxf6 6.Bb2#

It can also be found in the YACPBD chess problem database.


Is 9...Nxe5 recommended in this line of the Short Variation of the Advance Caro-Kann?

I think when Stockfish is saying +1 for black you kind of have to go for it - yes white gets a flurry of initiative but you can't avoid mess in every game. It's hard for humans to play messy positions but it will be hard for your opponent too.


Why did Garry Kasparov not play under the flag of Azerbaijan in his comeback tournament in the summer of 2017?

But why did Garry Kasparov not play under the flag of Azerbaijan?

Because his FIDE registration is with Russia.

If he wants to change his registration to Azerbaijan then the following also have to happen -

1) He has to have a valid claim like residency, nationality or birth, so birth would do.

2) Azerbaijan chess federation have to agree.

3) An administration fee has to be paid to FIDE and possibly a "transfer" fee also. Because Kasparov is a highly rated GM this would be very large. I think when Caruana transferred from Italy to US it was more than $50,000.

The section of the FIDE handbook which describes the rules is here.