Which line(s) pose Black problem(s) in the King's Indian defense on the highest level of competition?

GM Vassilios Kotronias has written a detailed series of books covering more or less every system that white can try against the KID. In the final volume of his series, he notes four systems as the most dangerous ones at white's disposal. These are:

Mar del Plata
Makogonov
Gligoric
Sämisch

As someone who has played the KID for most of my chess career so far, I can only say that Kotronias' assessment is more or less spot on (which shouldn't come as a surprise to anyone who has read his series on the KID). The main lines in these systems are truly nasty.
Edit: after rereading the question I wish to give a perspective on why top GMs refrain from using the KID. I don't believe the KID is an unsound opening, and from a theoretical perspective there is no specific line that causes black too much headache to deal with. The problem with the KID is that it carries serious risk for black, regardless of its theoretical status. Black will often need to "trust the engine" and enter dangerous and sharp lines in order not to fall into a horrible position (just look at what Grischuk had to do in the 2013 candidates tournament when he played the KID against Svidler - the line he played looks like the work of a mad man, but is in fact the only real way for black to maintain equality after 12.f4). While this risky play is fun, it is not always viable for a top GM. When you play the KID as black you cannot force a calm game, and for professionals who need reliable openings that they can play when they need at least a draw the risk that the KID carries is simply not acceptable.


The rating system already kind of allows you to calculate this since you can convert any rating difference into an expected score using the formula: expected = 1/(1 + 10^(diff/400)) so a rating difference of 382 points should give you the .9 expected score.

Therefore Magnus Carlsen at 2872 should score 90%  (which could be 9 wins and one loss out of 10 games or 8 wins and 2 draws) against a player rated 2490.  and that 2490 player should score the same against a player rated 2108 and so on.

So you could keep subtracting 382 from Carlsen's rating until you got to a rating of about 100 which is probably what the worst chess player could be.  if you subtract 7 times you get down to 198, so I guess you could say Carlsen is 7 of your levels above the weakes beginner.

Now a rating difference of 200 translates to about a .75 expected score  and that happens to be the rating difference that the USCF uses for different classes.  For example: Master = 2200 - 2399 /
Expert = 2000 - 2199 /
Class A =  1800 -1999 /
Class B - 1600 - 1799 /
Class c - 1400 - 1599 etc..

so you can kind of think of each class as a "level" like you describe where the middle of each class has about a .75 expected score against the middle of the next lower class. So you could say that using that criteria, Carlsen is about 14 "levels" or class above the weakest player.


What does "+-" mean in algebraic notation?

What does “+-” mean in algebraic notation?

This symbol means "White has decisive advantage", which means that White's advantage is big enough to secure him victory. As for symbol -+ it means "Black has decisive advantage".

  What does this notation mean?

This notation is introduced to bypass the language barrier so any reader ( Japanese, English, Arabian, Marsian, it doesn't matter! ) can understand the comment behind the move. In the old days before this notation, commentaries were given in words, which required the reader to know commentator's native tongue or to find the translation of those commentaries. This way, when commentator writes +- behind the move, everybody ( Japanese, English, Arabian, Marsian, it doesn't matter! ) know what it means. It is shorter and cleaner this way.

  Is it standard?

Yes, it is. The symbols were invented by Chess Informant and accepted as a standard. You can find out more about chess notation here.

  And why are the two games using it with the symbols in different order?

Because the positions in those games are different -> in one White has the decisive advantage while in the other it is Black who should win.

Hopefully this answer helped you. If you need further clarifications leave a comment. Best regards.


Is there a full tutorial for Queen vs Rook endgame?

Unfortunately, no "easy" fool-proof method is known. It can take 31 moves until the
 checkmate or capture the rook with best blay from both side in the worst possible
 initial position. Nevertheless, the queen can always win if the player with the rook
 has no perpetual check or a fast win of the queen or a stalemate trap.

In particular, you have to avoid stalemate traps. Human defence tends to lose faster
 because of the fear of putting the rook far away.

A difficult position is, for example W : Kd5, Qf7 S : Kd8, Rb6

where white has to find the counterintuitive move Qf4! which is not the only winning
 move but soon or later white must come to this idea to win.


It looks like he didn't quite integrate that the point of making moves is to win the game in the end.

A piece advantage is just a means of capturing more of an advantage (often, a queen via promotion), to easily crush defenses and mate. At least, that's what I'd go for with a piece advantage. If they don't have a piece advantage yet, then try and get it¹. I wouldn't call that endgame², though.

Now, being 8 years old, I think that this will just come as he grows and thinks more in terms of goals in a fight, and less as a game where you play moves according to some rules. I don't think you should worry about that if he's happy as it is. At least, not until he starts being bugged by “and now what” himself.

This question might be of interest.

¹ I wouldn't mind making capturing pieces the first objective of a young player once he knows checkmate is how a game ends. If he loses games while being ahead in material, he'll learn the difference.
² Endgame, in my mind, is about more equal positions, how to win and not draw, or how to get an endgame advantage. I'd call finishing a game with a piece advantage “finishing the work”, rather.


Problem: Find White's second-to-last move

White's second to last move must be f5+.

So, this is what the position looked like before White's second to last move -

   [FEN "b7/6pP/7k/7P/4PP2/2PP4/3B2KR/2Q1N2R w - - 0 1"]

   1. f5+ g5 2. hxg6+

How to arrive at the solution -

In this position, it is Black to play and the Black king is checked by a double-battery of the two rooks and the bishop and queen. What was White's last move?

        [FEN "b7/7P/6Pk/5P2/4P3/2PP4/3B2KR/2Q1N2R w - - 0 1"]

Since it is a double check, it must be some form of discovered check. However, since we have a double-battery, it cannot be possible that the discovered check was caused by a move of one of the pieces involved in the battery, because the other piece in the same battery would have already been checking the Black king if such were the case. Thus, it has to be some other "piece". But no such piece can uncover two attacks. Thus, it must be a very specific case of a pawn capture, an en passant, where two lines are opened at the same time.

     [FEN "b7/6pP/7k/5P1P/4P3/2PP4/3B2KR/2Q1N2R b - - 0 1"]

     1... g5 2. hxg6+

In the above, position, we see that the Black king is checked by a battery of queen and bishop. The only way that could have occurred in this position is if White played f4-f5.

Thus, White's second to last move is f4-f5.


Yes, pieces need to be properly placed. You can either tap the clock back and ask him/her to adjust his/her piece (which is what happens in many local level tournaments). It is generally better to check with the arbiter before the start of the game on what is the rule for handling such a scenario in their tournament since calling the arbiter mid-game can get you penalised.

The official FIDE site says that pieces can be adjusted only in each player's time.

I would suggest use your judgement and good sportsmanship sense and not call for the adjust for a small overlap but that is my opinion.


Which rule was recently introduced/modified in chess officially?

Do you mean what rules have been changed the most recently? FIDE, the international federation of chess, just changed some rules four days ago (2014 July 1). Changes include:

You are now officially allowed to promote a pawn by removing it from the board while it is still on the 7th rank and then placing a new piece on the 8th rank, rather than moving the pawn to the 8th rank and then removing it. You may also place the new piece before removing the pawn. (The move has not changed, just the list of allowable ways of executing it.)
If 75 consecutive moves have been played without a pawn move or a capture, or the same position has occurred for 5 consecutive alternate moves in a row, the arbiter is allowed to step in and declare the game drawn (without a player claiming a draw).
Players may not bring cell phones into the tournament hall at all.


Please critique my game (Caro-Kann, Fantasy variation)

On move 6, I'm not really sure why White didn't just play Nf3. After that, Black should play exd4 Qxd4 followed by (after Qxd4 Nxd4) just Bc5.

After Nce2, well surely exd4 makes sense, but I think Nf6 should have been considered, attacking the e4 pawn. Notice that anytime dxe5? is played then you have Bc5, with that mate threat that you already diagrammed (Bf2+ Kd2 Qe3#), so therefore you didn't have to give up the tension so early with dxe4. Nf6 develops and attacks e4 which is a critical point (a critical point is an unprotected piece/pawn or a piece/pawn with the same number of defenders and attackers on it. A critical point can also be a king or just like in the caters somewhere where you have weak squares and stuff. Attacking critical points is a key concept in torturing opponents or putting pressure in strategic chess).

By the way, I think Be3 is a medium good move... You are establishing a piece on the enemy's third rank or your sixth rank, which can be so strong in some middlegame positions that it is worth sacrificing an exchange for that piece and a pawn or something. The only other move I can think of is Re8, because there is a critical construction on the e-file with 2 knights on the e-file.

A critical construction is a rank, file, or diagonal where there are 2 or more pieces in opposition or just like a lot of pieces (regardless of color) on the same rank/file/diagonal. Critical constructions are very good for finding important tactics or defensive tactical resources that can involve double attacks, skewers, interference, etc. Therefore I think Re8 instead of Be3 makes a lot of sense. You are creating a lot of tension on the two knights and activating the rook.

Here is a sample line. 16...Re8 17. Nxc5 Nxc5 18. Nd4 Qa6+ 19. Kg1 (all other moves like Kf2 and c4 are just a worse version) Qd3 20. Bd2 (Qxd3? Nxd3 and now you are attacking 2 critical points which is the b2 pawn and c1 bishop, and you can take advantage of the critical construction on the second rank with Re2. On top of that, your knights easily get to the sixth rank or other strong squares) Ne4 21. Be1 Qe3+ 22. Kh1?! (Kh2 is just more accurate) Bxf2 23. Qxf2 and this should win, and all of White's lines were backed up by an engine.

P.s. On move 18 you missed ...c5, removing the defender of e6.

P.s. I think understanding critical points is something you mind as well learn anyway, and a technically possible answer to how you could have played this better. I think the opening was fine but you should have played Nf6 instead of exd4, because Nf6 develops while attacking a critical point which is e4, and you have a strong critical construction on the c5-g1 diagonal and tactical pattern if dxe5 which allows Bc5 and stuff.


Correctness of the lichess training solution (Puzzle:63063)

In case of 16.hxg3, Black plays 16...Qxg3+ when White has only two legal moves:

17.Kh1 Rf6 followed by 18...Rh6 is a quick checkmate.
17.Qg2 Qxe3+ and after the check is parried Black can already take back his piece with 18...Qxd3 (with already three extra pawns as a reward), or continue the attack with 18...Rf6. He's completely winning in both cases.

This exercise is a typical case of a demolition sacrifice: you give your knight on g3 to rip the opponent king of its protective pawns and mount a decisive attack.


Why did FIDE allow some random guy to open for white in Chess Candidates tournament 2018?

It is very common in top tournament that a local celebrity or other people who like attention such as politicains, people from FIDE, etc, make the ceremonial first move. This is purely for the photographers, and of course it is perfectly fine to take back this move and make your own move.

In the game you mention however Aronian chose to stick with 1. e4 which is of course also an option. I don't think that Aronian was in any way influenced by the choice of Francesco Tristano, i.e. he would have played 1. e4 anyway.


My database has 1603 games in the line 1.d4 d5 2.Nf3 Bg4, with Black scoring a poor 41.3%. (Contrast this with White scoring 54% over 38,587 games in the Trompowsky.) In particular, White does very well with the two responses that Steinitz used in the Chigorin match: 3.Ne5 leaves Black with a dismal 33.9% score, while 3.c4 leaves Black with a 34.7% score. So the numbers tell the story that this line is considerably worse for Black than the Trompowsky is for White, which explains why it isn't played much. (Nigel Short appears to be the only top player in recent times to play the line even a handful of times; he did score a nice rapid game win against Kasparov with it in 1987 though.)

Why the disparity in results, though? Well, the only difference between what White is getting in the Trompowsky and what Black is getting in your line is that White has gotten in the extra move d4; but that's a pretty significant extra tempo. To illustrate with just one concrete line, after e.g. 3.Ne5 BF5 in your line, White can strike Black's center immediately with 4.c4 and have a good game. In the Trompowsky, on the other hand, Black couldn't really do the same with 2...Ne4 3.Bf4 c5?!, since White could kick the knight and then push ahead in the center with something like

[FEN ""]

1.d4 Nf6 2.Bg5 Ne4 3.Bf4 c5?! 4.f3 Nf6 5.d5 d6 6.e4

when White has grabbed a lot of space and Black will lag behind in development. This is just an illustration, but the point is that White having already gotten in d4 is a significant plus.

So this line of Chigorin's really isn't good, but if you're interested in playing something like it, a better version can be had via 1.d4 d6 2.Nf3 Bg4, the Wade Defense (which I play myself sometimes). Now 3.Ne5 is no longer an option, and we have something much more playable for Black. Julian Hodgson himself (who greatly popularized the Trompowsky for White) has played this particular line quite a bit, which is good evidence that this is a fine way to play. (Not to mention, it's been played on occasion by folks like Petrosian, Anand, Grischuk, Ivanchuk, Svidler ...) Of course, playing 1.d4 d6 means having to be ready for the transposition into e4 lines via 2.e4, but if you're OK with that, then this is a perfectly good choice for Black.


Queen's Gambit Accepted : how should White continue after 3.e3 Be6?

[FEN ""]

1. d4 d5 2. c4 dxc4 3.e3 Be6 4. Na3!?

seems good to me-Black would not be able to hold the c4 pawn. I would take c4 pawn with the knight and head for e5. The other knight can bolster him from f3 and there will always be threats to f7 or to Blacks light squared bishop with Ng5.

  The Wikipedia article on Queen's Gambit Accepted simply notes that "... White has good compensation after 4.Ne2".

[FEN ""]

1. d4 d5 2. c4 dxc4 3.e3 Be6 4. Ne2 b5? 5.a4! c6 ( 5...a6 6.axb5 ) ( 5...bxa4 6.Nf4 Bd5 7.Nc3 c6 8.e4! ) 6.axb5! cxb5 7.Nec3!! Bd7 ( 7...Qd7 8.Qf3 Nc6! 9.Nxb5! ( 9.d5?-+ Nb4 10.dxe6 Nc2+ 11.Ke2 Qd3#) Bf5 10.Nd2 Bd3 11.Nxc4+- ) 8.Qf3 Bc6 9.d5 Bd7 10.b3! Qc8 ( 10...b4 11.Bxc4!! bxc3? 12.d6!+- Bc6 13.Qxf7+ Kd7 14.Qe6+! Ke8 15. d7+! Qxd7 16.Qf7+ Kd8 17.Qxf8++-) 11.bxc4 b4 ( 11...bxc4 12.Na3 ) 12.Na4 Bxa4 13.Rxa4 a5

I bet that strong engine can find even better compensation for White than one I provided above, but I also think that my lines are sufficient as well.

  What about Qc2 to add further pressure to the c4 black pawn?

It should work, but you will needlessly complicate matters too much.

Hopefully this answer is what you were looking for.

If you have further questions leave a comment.

Best regards.


Do Barry attack and 150 attack really work that well with Colle-Zukertort?

There is a book which recommended this repertoire, A Killer Chess Opening Repertoire by Summerscale.  I used those lines myself when I was in the 1400 to 1800 range, but had to give them up as they were holding back my development as a player.

As a beginner, frankly you shouldn't be worrying about it.  Choosing a repertoire should be near the bottom of your list of 'areas to improve.'  How many games have you won/lost because of familiarity with the opening?  If anything, try to play good, normal, open lines, like 1.e4 e5, and just focus on the chess.  You'll get more out of that than by studying the nuances of the Barry Attack.


An efficient program, which generates all next moves for all pieces in C/C++

I think it is unreasonable to ask for this as a stand-alone program because its implementation will be very dependent on the design of your program as a whole. In particular, it completely depends on how you are storing each position: how are you representing the board and pieces? How do you keep track of where each piece is after each move? How do you know which squares a piece can move to (is there a piece there already? Is there a piece blocking the bishop's movement as it goes from c1 to f4?)?

Of course, once you have a implemented all of the above perfectly then the problem of generating the moves that each piece can make becomes quite easy: simply iterate over every piece and for every piece iterate over all of its valid moves (how you store moves is, again, entirely up to you).

Finally, this is a great resource that gives a good overview of some important topics in chess programming.


First off, let me say I've not put your game through an engine. I'm assuming you can do that yourself and in any case they're not terribly good at endgames.

Now for some appropriate general principles and observations:

1) King, Knight and pawn endgames are very similar to king and pawn endgames. The same kind of principles apply. With enough pawns on the board and an extra, distant passed pawn you should be looking for the win.

2) If the knights come off then it is an easy win for you

3) If too many pawns come off it is an easy draw for your opponent. He seems to have known what he was doing from about move 33 because with pawn advances and good use of his knight that is exactly what he achieved.

4) Two related principles. Pawns can only move forwards. They cannot move back. Patience is often the key to good endgame play. The immediate 33) ... b5 is too impatient.

5) On a4 your knight is badly offside. Your first task, given your opponent's immediate lack of threats, should be to get it over to the kingside where the action is. d4 looks like a wonderful square.

6) By the same token your opponent's knight is also in need of some improvement. d5 looks like the right square. From there it keeps half an eye on your b pawn, stays in touch with the kingside pawns and threatens your f6 pawn. Either your king is going to be tied down to its defence or it is going to have to advance and be swapped off. One small step closer to a draw. You should try and prevent this.

So, what I suggest for your first possible mini-plan is Na4 - c5+ - e6 - d4.

What happens next depends on white's reaction. I think it would be a mistake for him to go for your b pawn with something like Kd3 - c4 - b5 - b6. You would go for his pawns with your knight starting with Nc2 with the threat of Ne1 forking the f3 and g2 pawns. After Nc2 one possible (non-forcing) line might be:

1) g3  h5 2) Nf2 Ne3 (now aiming for f1 forking the h2 and g3 pawns) 3) h3 Nf1 4) g4 h4 and white's pawn structure is badly compromised.

More sensible for white would be a compromise where he plays Kd3 - c4 but then aims for Ng4 - e3 - d5+. Black might counter this by Ne6 - f4 instead of d4 to temporarily prevent Nd5+ and to start harrying white's pawns.

A second possible mini plan for black would be to start with Na4 - b2+. If white plays the tempting Kd3 - c3 than the paradoxical Nb2 - d1+ followed by h5 is going to force the knights off at the cost of a pawn when black's outside passed pawn plus better king position is going to win it for him.

So white can't play Kd3-c3. So white needs to play his king to c2. Then black can play his knight to c4 to prevent white's knight coming to e3 and protect the knight with b5 if attacked by the king.

If white goes after the b5 pawn with Kc3-b4 then black forces the white knight to the more passive f2 with h5. Rather than defend the b5 pawn passively with Nc4-d6 he could go after the white pawns with Ne3. Then I would suggest a (non forcing) sequence something like this:

1) g4 h4 2) Nd3 h3 3) Nf2 Nc2+ 4) Kxb5 Nd4+ 5) Kc4 Nxf3 6) Nf2 Nxh2 and, OK, with just 3 black pawns left it is looking difficult to win.

So, either defend the b5 pawn with Nd6 or go back to the Na4-c5+ plan.

If either of these two plans is black's best I'm not good enough to say, but they do pose white major problems to steer it to a draw. You have to make it as difficult as possible for white to find good moves in these positions.


In this case it's tactical. d4 looks like a really strong move but the problem is after 12...d4 13. Bxf6 black has to play 13...gxf6 because 13...Qxf6 drops a piece to 14.Ne4.

However, if you play 13...g5 first followed by d4, then d4 trades off the isolated pawn and equalizes for black. Black also has a little bit of an initiative going at that point.

In general, you don't want to move the pawns in front of your king if you don't have to or unless it benefits you (like in this example).

How to deal with pins? Study unpin combinations. There are a lot with sacs on f7/f2 and h7/h2. There are also some where the knight captures like Legal's mate or captures on d4/d5 sometimes winning a piece.

You can also play actively. For example creating a threat with the queen and then moving the knight to a center square or just playing aggressively in general will sometimes make the pin meaningless. You also have to remember an early pin by the queen's bishop is usually bad. For one it leaves the b pawn unprotected but also if you haven't castled on that side he isn't really threatening anything.

Lastly, if the opponent captures and doubles your pawns that's not always bad. For one, that means you have the two bishops and an open g-file which is typically the file right in front of the opponent's king. It depends on the position but it's not uncommon for your opponent to hand you a ferocious attack by capturing the knight.

Just as an example, to illustrate some points, this is a game I see at least once a week in blitz:

1. e4 e5 2. Bc4 d6 3. d4 exd4 4. Nf3 Bg4 5. c3 Nc6 6. Qb3 with a double attack on both b7 and f7. Black has a lot of ways to go wrong in this position and 6...Bxf3 (which leads to 7. Bxf7+, Ke7 or d7 8. Qe6#) is fairly common.


I think you got it basically right. White gets the bishop pair which in an open position like this, is a real advantage. Also black currently does not have any good squares for his pieces. Lastly, it is difficult for black to take advantage or to attack the doubled isolated pawn.

White's dark squared bishop could go to g5 where the pin of the knight is kind of annoying or to a3 where it might hinder black from castling.

Regarding your proposed continuation, I believe that after 7...Bxc3 8.bxc3 d5, white can play 9. e5 asking the knight where it wants to go. Also after black's d5 the a3-f8 diagonal gets weak and the bishop on a3 will be really strong.


Is there an objective measure of how "complicated" or "tension-filled" a chess position can be?

To me, a position looks "tension-filled" only when there are many threats on the board and (the important part!) - when these threats are mutual. A position that contains many threats but all of them being made by one player - that's rather realization of huge positional advantage.

I don't know very well the quality notation of moves in English chess books, but in Russian ones some moves get the '!?' quality notation, which means "this is a slightly risky move that can give you advantage if your opponent fails to find the right countermove (which is not trivial to find, that's the whole point of the idea), otherwise your position will get worse".


Playing on in a hopeless position when it is clear to you that your opponent has the knowledge, skill and time to finish you off is never honourable. It shows a lack of respect.

If you have played your moves much faster than your opponent so that he is in serious time trouble and you aren't, then it is perfectly reasonable to play on. With just a few seconds left playing without increment he may not have enough time to deliver the coup de grace.

In the reverse situation where you are the one with very little time on the clock it is excusable but perhaps not particularly honourable to play on as you can always claim that with so little time to think the hopelessness of your position hadn't sunk in.

Note that positions where you have very few moves and so stalemate is a possibility are not hopeless. Nor are positions where, although material down and so expected to lose with best play, you have some prospects of counterplay in a double-edged position.


You have little chance in your dissertation of surpassing state of the art chess engines. Perhaps you could find a hook which hasn't been explored so much. One idea is to train your program to play amateur chess in a convincing way. Can a program pass a sort of chess Turing Test where a human-player couldn't tell if they were playing an AI or playing a player rated e.g. 1600? When I play computer chess programs with a level setting at a level that I can actually beat, there is something not quite right about it. The program is deliberately hobbled (so I can beat it) in such a way that it sometimes makes blunders that a human player of the target level is unlikely to do, but at other times it still makes moves which seem just too good for that level. Trying to imitate human chess-playing rather than targeting optimal chess-playing seems like an interesting AI problem.


What should a chess beginner do with his/her knights after 2. Nf3 or 2. Nc3?

The knights don't necessarily move beyond the third rank in the opening. The middlegame is more variable and depends on the opening, but I think the main "rule" you need to remember is that knights, being slow pieces, work best when they are supported. You generally should avoid advancing a knight unprotected, where it could be lost to a tactic. The best support for a knight is a pawn, but also you don't want your knight to be "kicked back" by an enemy pawn (unless that move would be bad for your opponent for some other reason), so the ideal square for a knight is an outpost, which quoting the Wikipedia definition is "a square on the fourth, fifth, sixth, or seventh rank which is protected by a pawn and which cannot be attacked by an opponent's pawn."

One more thing to consider is that, if you castle short, the f3 knight also has an important defensive role since it defends the h2 pawn, which is often a target of attack. That doesn't mean you can never move the knight, but you should be wary when there are enemy pieces threatening that pawn. A famous attacking pattern known as the "Greek gift" begins by sacrificing a bishop for the h2 pawn (or h7 against Black, of course!).


Why is white in trouble in the following endgame?

What's bad for White in this position is that his structure is already slightly worse (isolated a-pawn), and that Black can worsen it further. White's advanced d-pawn is actually a liability that Black can readily attack by bringing her king forward. The pawn will prove difficult to defend, and at the very least Black can basically force White to accept being saddled with two isolated c-pawns as well by playing ...c6 at some point (when the alternative would be to lose a pawn straightaway on d5).

Is this enough to mean that White is necessarily lost? Probably not (though I certainly wouldn't fancy trying to hold it against a strong engine). But the point is that Black doesn't have similar structural weaknesses, and so she doesn't have the same natural targets to deal with (her doubled pawns aren't nearly the liability that White's are), while White will be forced to keep an eye guarding his queenside. To my mind, this is enough to explain Stockfish preferring Black.

Unfortunately we don't have inline annotations active for the site's PGN viewer, so I will let the verbal explanation already given suffice, and provide just a handful of variations illustrating the points given.

[fen "5k2/pppb1pp1/5p2/3Pn3/4B3/2P2N2/P1P3PP/6K1 w - - 0 1"]

1.Kf2
    ( 1.Nd2 Ke7 2.c4 f5 3.Bd3
        ( 3.Bf3 Kd6 4.Kf2 Ba4 5.c3 c6 6.dxc6 Bxc6 )
    3...c6 4.dxc6 Nxc6 )
1...Ke7 2.Ke3 Kd6 3.Kd4 c5+ $1 4.dxc6
    ( 4.Ke3 $2 Ng4+ 5.Kd2 f5 6.Bd3 Kxd5 )
4...Nxc6+ *


Number of positions with specifically a number of pieces

This answer is extended from my comment to Ross Milikan's answer to your question Numerical FEN writing.

There is a website devoted to counting the number of legal positions up to equivalence with given number of pieces. Currently they have results for positions with 2 to 8 pieces.

2:                     462
3:                 368,079
4:             125,246,598
5:          25,912,594,054
6:       3,787,154,440,416
7:     423,836,835,667,331
8:  38,176,306,877,748,245

With their definition, a position is legal if:

It has exactly one white and one black king
There are no pawns on the 1st and 8th lines
Side to move is not giving a check

Note that with these definitions, some positions could be legal even if they cannot be achieved in a real game. Edit: As @Pimgd pointed out in the comments, an example is a position with white pawns on a2, b2 and a3.

Two positions are considered equivalent if they are essentially the same, in this case, one position can be obtained from another by combining the following operations:

Any position: Swapping the colours of the pieces, the side to move, and mirroring the position around the horizontal line such that the square a1 becomes a8 etc.
Positions with no castling rights: mirroring the position around the vertical line such that the square a1 becomes h1 etc.
Pawnless positions with no castling rights: mirroring the position around the horizontal line such that a1 becomes a8 etc.
Pawnless positions with no castling rights: Mirroring the board diagonally

Depending on the existence of pawns and castling rights, each "unique" position thus corresponds to 2 to 16 different positions.


Is there any website where I can play simultaneous chess against many opponents?

You could do that on FICS, here's how:

Simuls

  "Simuls" = simultaneous chess matches; playing more than one opponent at a
time.  It is possible to play more than one opponent simultaneously on the
chess server.  Below are sections for Starting a Simul and for Joining a
Simul.

  Users using an interface that only supports a single board (that is if
two games are being observed a move from the second game will cause the
position of the first game to disappear  (such as Winboard and Xboard)) should
issue "iset singleboard 1" before starting a simul.  This will ensure that
when simul participants move, only the board the simul holder is at will
update.

STARTING A SIMUL

  In order to play more than one chess match simultaneously you need to do the
following:

1. Start the simul with the "simstart" command.  Announce your simul
   conditions on shout and cshout enough to get the word out, but not so much
   as to annoy users.

2. Other users must then challenge you with "simmatch".

3. Accept or reject the challenges as they come in.  The first game will be
   colored as is if was an ordinary match.  The next game will be the
   opposite color, the next the opposite to that and so on.

4. When you are satisfied that you have started the number of games that you
   can handle, turn off your open flag with "set open 0".  You can see your
   games with "simgames".

5. You can then start making moves on the board.  The "simnext" command moves
   you to the next board; "simprev" moves you to the previous board.  You
   will focus on one game at a time, going in a particular order.  If you
   wish to skip to a board of particular interest "goboard <player>" or
   "goboard <game number>" will take you to that board.

6. If you are bothered by how long a player is taking to make the next move,
   or they are being disruptive you can abort that game with "simabort".  You
   can also force an adjournment with "simadjourn".  Only games adjourned
   during the simul can be resumed.  After the simul any outstanding simul
   games may be resumed as normal matches.  Should there be a need to
   terminate the simul "simallabort" and "simalladjourn" will abort or adjourn
   all games respectively.  Both commands will also terminate the simul.

7. When you are finished type "simend".  This will return you to normal
   playing mode and inform you of your statistics for the simul.

Various commands you can use while running a simul include:  goboard,
simabort, simadjourn, simallabort, simalladjourn, simnext, simprev and simend.

JOINING A SIMUL

  In order to play against a user who is open for playing simultaneous
matches, here is what you do:

1. Using the "simmatch" command, challenge the person you will be playing.

2. You will be informed when the simul player is coming to your board.  You
   should be prepared to move either before or shortly after that player
   arrives at your board.  If you do not move within a reasonable time
   period, your game could be aborted.

3. It is impolite to offer a draw unless that player is at your board.  It
   could very easily confuse the simul player if offers come in from
   different users at once.

OBSERVING A SIMUL

  You can observe all games in a simul once they have started by typing
"simobserve simul_player".  All of the simul_player's simul games will be
added to your observation list.  As the simul_player moves from board to
board, so will you.  When the last game has ended, you will see the final
results from the simul games.  You can also use the "follow" command for this
purpose.  Using the "observe" command, however, is not reliable for this
purpose.

Reference.

I don't know if it affects your rating, never tried it. Be careful what you wish for :)

There's also RedHotPawn, it says that  it offers that, maybe a member can verify that, I signed up there a year ago never used that site. But it's the second most popular online chess website after Chess.com I believe.

PlayChess server offers that as well but it's not free, but it's well known server, best of the best.

On Chess.com, you could play live chess and duplicate tabs, and you'll end up playing more than games at once, not the same window though.

There's also gameknot.com, I have never heard of it, but they claim it is possible to play such games on their site.


What are the time rules in Candidate Tournament?

Per the official rules, section 3.5: 120 minutes for the first 40 moves, 60 minutes for the next 20 moves and then 15 minutes for the rest of the game plus an additional 30 seconds per move starting from move 61.


You may consider doubling rooks if:

There is an important open-file, and you want to make sure you have firm control on it. You want to minimize your opponent's controls to the file. (very common).
There is a semi-open file with an isolated or backward pawn. The pawn is protected by your opponent's rook. You want to win it. (very common)
If you want to exchange both rooks.
If you want to improve the position of your rooks. In particular if no other good squares for the rooks to go.
You have something to pin on the open-file, and you want to win it (look at the game below)

You may want to study the classical game between Alekhine and Nimzowitsch. Look at the final position:

  http://www.chessgames.com/perl/chessgame?gid=1012683&kpage=1

Here, you have absolutely no reason not to double your rooks for both sides. Nimzowitsch had to double to protect his c6 knight. Alekhine had to double his rooks to win the c6 knight. Note there is an open c-file and no any other good squares for the rooks.


In encountering a draw by [x number of moves], when does the draw actually occur?

Typically for the 50 move rule it's 50 ply from both sides without a pawn move or capture so the claim can only be made AFTER 50 moves.  The position on the board always stands so checkmate is checkmate.


What are some good attacking games from the black side of the Queen's Gambit Declined (Exchange variation)?

A suggestion :

Boensch-Vaganian, 1983

Bring the Bishop to d6, move the kingside pawns forward, try to dominate square e4.


Ideas in Sicilian Defense: Staunton-Cochrane Variation

When you push d4 early on, the general plan is to protect the d4-square and e4-pawn, while developing quickly. With your king out of the centre things tend to become easier, and you can focus on more long-term plans. Meanwhile, if Black clamps down on the d4-square with ...e5, then they have also weakened their d5-square. Here the plan is to capitalize on the d5-square (not necessarily with an immediate Nd5), and to play on the flanks (for example, with a3, Rb1, b4).

I'll outline some theory for the lines you mentioned in your comment. At the end of my answer I'll give what I think is a better way to play the e4+c4 system.

1.e4 c5 2.c4 Nc6 3.Nf3 e6 4.d4 (delaying d4 with 4.Nc3 and 5.Be2 is also possible) 4...cxd4 5.Nxd4 Nf6. After 6.Nc3 Bb4, your e4-pawn is under attack. It is best to defend it with your light-squared bishop, but right now Bd3 loses to ...Nxd4. So you should play 7.Nxc6, and now there are two main responses:

7...bxc6 8.Bd3. Now Black may strike in the centre with ...e5 or ...d5 (before or after castling). For example, 8...e5 (8...d5 is met with 9.exd5 exd5 10.0-0) 9.0-0 0-0 doesn't give White any advantage, but the position is playable. A possible continuation is 10.Be3 Bxc3 (10...d6 could be met with 11.Qc1 followed by a3, since ...Bxc3 no longer gives you doubled pawns) 11.bxc3 d6 12.c5!?.
7...dxc6 8.Qxd8+ Kxd8 9.e5! Ne4 (or 9...Nd7 10.Bf4, followed soon by 0-0-0) 10.a3 Bxc3+ 11.bxc3 may give White a pull. He has the two bishops, while Black's minor pieces aren't that good (for different reasons). Note that 11...Nxc3?! should be met with 12.a4, when White may meet ...b6 with Be3 and a5. He has enough compensation for the pawn to claim an edge.

1.e4 c5 2.c4 d6 3.Nc3 Nc6 4.Nf3 g6 (4...e5 looks good for Black). Here White should play 5.d4 cxd4 (or 5...Bg4 6.d5 Nd4 7.Be2) 6.Nxd4 Bg7 7.Be3, but now this transposes to a line in the accelerated dragon. The theory here is well developed, and I'm not sure if this is what you're interested in, considering with 2.c4 I assume you're trying to avoid Open Sicilian lines.
1.e4 c5 2.c4 Nc6 3.Nf3 e5 4.Nc3 d6. Here I don't like the immediate 5.Nd5, and instead 5.d3 looks better (followed by Be2, 0-0, etc). The problem though is that Black can push ...f5, whereas you can't push f4 since the knight is already committed to f3. This gives Black at least equality, and while the line is playable, it would be better if your knight was on e2. After castling you could try playing on the queenside with a3, Rb1, b4 (and Nd5 if the position calls for it), but Black's kingside play looks easier.

In my opinion, due to the possibility of Black playing ...e5, I think it's best not to play Nf3. Instead, a setup with Nc3, g3, Bg2, Nge2 looks stronger. Then, you may continue developing with 0-0, d3, Be3, Qd2, f4, etc. The d4-square will remain a hole for now, but in general your setup is pretty harmonious. In addition, you can play it against a variety of different systems Black has.

A good introduction for this opening on YouTube is a video on the Botvinnik-English system by the Melbourne Chess Club channel.


What is the most agressive, tactical, attacking, line in this Mieses?

I think you are mixing some variations. In the main line Mieses, certainly 9.b3 and 9.Nd2 are two of the most played moves:

[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4 Nf6 5.Nxc6 bxc6 6.e5 Qe7 7.Qe2 Nd5 8.c4 Ba6 9.b3 {This is the main line.} (9.Nd2 {This is the third most common move.}) (9.g3 {This is the second most common move.})

However, in the position you are concerned with, you may be much more aggressive than any of those moves. Black has wasted yet another tempo with his knight, and bear in mind that you don't need to overprotect the c4 pawn as it is already protected by two pieces. Possibly the best move is to develop another piece and go for a mating attack as early as possible:

[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4 Nf6 5.Nxc6 bxc6 6.e5 Qe7 7.Qe2 Nd5 8.c4 Nb6 9.Nc3! {The knight can be developed to a more active square, and has more control over the center, which will be extremely important, since in the main line black gets a passed pawn and white will need to control it.} Qe6 10. Qe4 g6 (10... Ba6 {Should also be looked at for white.}) 11. Bd3 (11. f4 {Is a possible different move order, perhaps over aggressive, which may transpose or get into completely different territory.}) Bg7 12. f4 O-O 13. O-O {This is more or less a common subvariation of the Mieses.} Ba6 14. b3 d5 15. cxd5 cxd5 {Around this move, the book/theory begins to get fuzzy and some other interesting responses have been tried.} 16. Qe2 (16. Qf3 {Is also to be considered.}) Bxd3 17. Qxd3 c5 18. Ba3 Rac8 (18... Rfc8 {Is also valid, but offers slightly smaller chances.}) {This is the main subvariation line, but quite a few digressions are possible.}

Although the position is roughly equal, maybe with a slight plus for white, to make a small mistake is very easy, and those mistakes come with great doses of punishment and pain, since a little slip in these lines will very likely cost the game. White has to be constantly looking out for moves like f5 (which can be played even if the bishop has not been fianchettoed) and black has to avoid getting crushed by the bind the e5 pawn makes. This is not a position you can play mechanically and positional, but a very complex tactical struggle.


Why is my tactics spidey-sense not working?

Developing tactical ability is a long process. At first you expose yourself to new patterns, try to understand how they work when they are already on the board. You will still not spot it every time it appears in your games. But sometimes you will. And sometimes you will see that you or your opponent cannot play a move because it fails due to a tactical motif you know.
The next step is seeing the potential motif long before it appears and setting it up. It is good that you note weaknesses in your opponent's position. This is the first step towards setting up tactics. You see a loose piece, you position your pieces so that eventually you can exploit that.
It takes a very long time from knowing a pattern to setting it up yourself. Be patient. Sometimes I see a tactic by GMs and I can barely solve it with all the pieces already in position, and then I realise they saw it 10 moves ago and played towards it and all I can do is hold my head.
It may be the case that your training method is not suited for you. Studying random puzzles, not sorted by patterns or some overarching theme, may not be good for you. It is good for pure calculation, but not when you are trying to develop your pattern database.


Puzzles that highlight the finiteness of the chessboard

Now that's a refreshingly different kind of question :)

It's probably easier to compose such a problem than to search for one, but that said, there's one that comes to mind:

 [Title "White to play and win"]
 [fen "8/5N1k/8/7b/1b5N/1K6/1B6/8 w - - 0 2"]

Hint:

   You want to keep all 3 pieces as white in order to win. Try to set up a trap on the b4 bishop by setting up a discovery on the black king.

Solution:

   1.Ng5+ Kh6 {only possible attempt to keep material} 2.Bc1 {Double threat: discovery on the king and threatening to take on b4, the trap is set} Ba5 {Any other move drops the bishop to a discovery check} 3.Ka4 Bb6 {only move again} 4.Kb5 Ba7 5.Ka6 Bb8 6.Kb7 {bishop falls.}
 From move 3.Ka4 it had become clear where this is going: the white king keeps shouldering the bishop until it hits a wall and cannot escape anymore. Now on an infinite board, this trap would have been impossible as the king and bishop dance would have continued endlessly.


What are some methods that tournaments use to limit draws?

The problem with chess having a large number of draws cannot itself be solved - it is simply a result of the defensive possibilities in many systems and the fact that high-level play reduces the number of losses due to simple mistakes. Without a fundamental change to the rules of chess this is not likely to change.

There have been several measures to prevent top players from agreeing to draws before the positions are completely played out, which I'll mention below. One thing to keep in mind, however, is that draws by agreement are often used by players in long tournaments as a way of preventing fatigue or simply playing on in dead positions until someone makes a mistake, and it's up for debate whether forcing/encouraging play in such conditions makes for chess that is more interesting or of better quality, or if it detracts from the events in which those rules are used.

The most commonly talked about variant is what are known as 'Sofia rules' (introduced in a tournament at Sofia in 2005), which states that no draws can be agreed before the position itself becomes a theoretical draw, though this assumes that the arbiter is theoretically competent enough to realise that the drawn position is a draw, and doesn't stop the players deliberately trading down into such a position.

The main other option that has been suggested is to provide more points for a win than for a draw, thereby hopefully making the players want to push for a win as a win and a loss is still worth more points than two wins. There has been some discussion that this is unfair to players in hard-fought draws, however.

I'll also link you to this wikipedia article, which lists some other things that have been suggested over the years.


Here are a couple of games I found (although they do not really feature a diagonal king march):

Carlsen - Hracek
Carlsen - Pelletier
Adly - Carlsen
Carlsen - Aronian
Kramnik - Carlsen
Pelletier - Carlsen

I cannot resist adding following king marches:

Short - Timman, the most elegant king march I have ever seen.
Gashimov - Grischuk, the most chaotic king march I have ever seen.
Navara - Wojtaszek, the bravest king march I have ever seen. It should be added that it was part of Navara's preparation.


Playing a line in QGA from a QGD for White

After 1.d4 d5 2.c4 dxc4 3.Nc3, 3...e6 is a pretty weak response due to 4.e4!. In your example, you can reach that exact position, where you basically take as much space in the center as you want for free. Sure it's not the type of position you're probably used to, but that's only because this one is actually a lot better and Black rarely allows you to reach it.
In other words, you'll succesfully achieve all the goals in the Queen's Gambit. You'll retake the c4 pawn and get a massive center with your e4+d4 formation all of this while keeping your king safe and your pieces developped!
Furthermore, an e5 reaction is one of the main resources Black has against our d4+e4 formation, so e6 was pretty much a lost tempo


Start here: http://psmcd.net/otherfiles/BenefitsOfChessInEdScreen2.pdf

There are a number of reasons. Probably the most prosaic is that the brain is like every other muscle in your body, the more you use it the stronger it gets. Add to that the fact that chess gives you practice at breaking down a large goal into achievable steps (going from "Checkmate my opponent" to "First I need to get my pieces in position to attack, then I ...") and spatial reasoning ("A Bishop there will prevent his knight from attacking me here"). Add in teaching just a bit of empathy ("what move would I make if I were in my opponent's position") and it's a solid win all the way around.

The evidence shows that chess definitely improves performance in school. And recent research in Neuroplasticity indicates that learning chess can help an old brain stay limber longer, so there's even proven benefits for us Old Pharts(tm).


What is the theory behind center control?

The center is the crossroads of the board. Controlling it will give you access to every other part of the board. At the same time, it will drive a wedge in the opponent's position that hampers communication between king and queen side.

Control of the center is usually a decisive advantage in your favor; unless your opponent has heavy compensation (e.g. more than a pawn of material advantage), or a violent attack against your king.


Rearrange chess diagrams (from an opening) in order. Useful as a puzzle?

Nice fresh idea! I would not use it exclusively for opening training, but whatever works for your target group. Could be fun for younger players I guess. A few problems I see with this approach:

When doing the exercise I was basically only looking for small changes from the previous diagram. I mean, for me it did not matter at all that I was looking at a chess board. It could as well have been a series of paintings (with incremental changes) or anything else. If people solve it the same way as I did, I doubt that they get much out of the puzzle for chess.
I found looking through nine diagrams already quite time consuming, so I guess getting very deep (say 20 moves) is not very pracical.
Including side lines seems impossible unless you create a puzzle for each side line, however in that case you would lose the connection between them (i.e. that at move x you have options a, b and c...).
IMO, beginner players should focus on learning general opening principles, the reason behind making those moves and typical plans in certain pawn structures. Your approach seems to train learning lines by heart, which I don't find useful, because they'd be lost immediately once they are out of book.

Perhaps puzzles like these could be more useful for tactics or for basic endgames!?

Or perhaps, for slightly advanced players, it could be useful to have something like this, not move-by-move, but only showing relevant positions (tabiyas) skipping over intermediate moves.


Hm, my idea is this:

pawn structure should remain as is except pawn should be probably on
g6 preventing king side attacks and giving space to move bishop
Be7-f6-g7
move knight to better position Nf6-d7-c5 and focusing attack on weak
pawn a4 with help of white squared bishop
move black squared bishop to a1-h8 diagonal which will make pressure
on pawn c3 if white b pawn is moving to protect a pawn

It doesn't look as good endgame for black since he has minority on queen side which can quickly turn into passing pawn therefore I believe black should keep pieces.


In a chess there's a 3-fold repetition rule, if the same position appears 3 times, a player can call a draw. Your opponent allowed a 3-fold repetition, hence, the game was drawn.

3k4/8/p1PK2p1/1p4P1/1P6/P7/8/8 w - - 11 57

Edit: clarifying in light of comments:

Note that the draw does not happen until claimed by a player, and since you didn't claim it, your opponent must have. Why would they claim a draw in a winning position where they had more time on their clock? On lichess.org, you can control the "claim draw on threefold repetition automatically" setting. Yours is set to "when time remaining <30 seconds", but the opponent's must have been set to "Always". Players who normally play under faster time controls sometimes use the "Always" setting to ensure predictable draws under time pressure. You got lucky in this situation because your opponent didn't recognize the 3-fold repetition, and their winning chances were undone by their settings.


Why isn't the English Attack popular vs. the Sicilian Kan?

The English attack is only true mainline for the d6 Sicilian. The reason behind this is that in the e6 Sicilian variation, it's a lot easier for black to pressure your center and break through with a quicker d5. Specifically, black can play a fast Bb4 (pinning your knight and therefore influencing the all important e4 and d5 squares), and break out with d5.

[FEN ""]
1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 a6 5. Be3?! Nf6 6. Nc3 Bb4! 7. f3 O-O 8. Qd2 d5!

Even if black is worried about the pawn structure changing with white playing e4-e5 after d5, then he is fine too if he plays Qc7 instead of O-O to cover the e5 square. Regardless of the exact move order, as soon as black gets in the d5 break, then it's black who is slightly better out of the opening, not white. This English attack setup is too slow against the Kan. Instead of Be3 and a later f3, Bd3 is often used to defend the e4 point and avoid most of the sting out of the Bb4 pin.


What's a good middlegame book like My System for Expert Class?

I would recommend Mark Dvoretsky's book 'Strategic Play' Olms. ISBN 978-3-283-00418-7.
It's a part of famous 'School Of Chess Excellence' series. (it's easy to find it online). I personally bought all four of them:
Endgame Analysis,
Tactical Play,
Strategic Play,
Opening Developments.

Mark Dvoretsky is considered one of the best chess trainers of all time, he raised a number of leading international grandmasters.


Are there any gambits which yield an advantage for the side down material?

While it's a gambit by Black, what about Tal's gambit?  Black is scoring 55% in 228 grandmaster and elite correspondence games after 1 e4 c5; 2 f4 d5; 3 exd5 Nf6.  I'd call Black doing better than 50% in that many top games an advantage.  (And 55% is better than Black's score in any of the main non-gambit responses to 2 f4.)


Finding a plan in the Archangels Spanish when white plays Be3 to exchange the dark-squared bishop

In the final position, the black pieces are pointed toward the king side, so logic says that you should attack there.  The two obstacles are the bishop pinning the f-pawn and the control provided by the doubled e-pawns.  Stockfish pushes the a-pawn to chase away the bishop and uses the queen to apply pressure on e3.

  Pressuring and exploiting white's dark-square weaknesses

I prefer the immediate d5.  This neutralizes the bishop and forces white to decide between exposing a weak pawn on d3, accepting the isolated and doubled e-pawns, or liquidating the center with d4.  It's possible to delay the d5 break with the restraining move c5.

  Quick d5 break: challenging white's light-square control & backward pawns.

On move 11.Be3, exchanging bishop seems to be the only move for black.  Allowing white to exchange ruins you pawn structure.  The weaknesses on e5 and c5 are greater than the exposed d3 pawn weakness.

  Trade of bishops on c5 leaves black with 2 weakened pawns.


Jesus De La Villa's 100 Endgames book: Ambiguity

Those endgames are fundamentally different - one has rook pawns and a distant passed pawn (83); the second has rook pawns and a passed bishop pawn on the same wing (85).

The reason in the second case (85) is you may need a tempo move with the rook pawn on its original square. It's explained very clearly in the book.


Seeking an explanation for Nezhmetidnov’s queen sacrifice

White doesn't get only one bishop for the queen, but two pieces: a bishop and a knight.
Moreover, Black's weak king, White's domination of the center, great outposts for his pieces and lack of prospects for Black's development (especially his rooks) fully compensate the material imbalance.


Why is exchanging the queens bad in this position?

I think it is because 21.Rfc1 wins the c7 pawn. If black responds with a queen trade, she can't defend the pawn on c7 because white's bishop can attack a defending rook on c8 or d7.

[White "NN"]
[Black "NN"]
[FEN "3r3r/2p1kppp/B2qp3/2Qp4/6b1/PP2P3/3N1PPP/R4RK1 w - - 0 1"]

1. Rfc1 Qxc5 2. Rxc5 Kd7 3. Rac1 {and the pawn falls}

That said, the position is completely winning either way and exchanging off the queens is a practical decision that reduces risks and keeps everything under control. White has an extra piece and a passed pawn.


Famous grandmaster games of "torturous" winning or flaunting out of arrogance?

Are there such examples of torturous winning, where a grandmaster
resists his urge to resign and lets the opponent take all of his
pieces before he gets checkmated?

No, there aren't, for the simple reason that that sort of behaviour would require both players to behave in an extremely childish manner and childish behaviour (e.g. "hope chess") is something you have to eliminate to become good enough to become a grandmaster.
The aim of the game is to checkmate the opponent, not take all their pieces. Good players understand this. All grandmasters are very good players. Delivering checkmate gives most adult players and all strong players far more pleasure than taking all the opponent's pieces.
What you do see sometimes amongst strong players, including grandmasters, is the player who is defeated by an unexpected tactical blow, which leads inevitably to checkmate, allowing the checkmate rather than resigning when it becomes clear what has happened. This is seen as particularly sporting behaviour. Normal behaviour would be to resign once it becomes clear. Spiteful behaviour would be to resign one move before checkmate.


If one of the rooks has moved from its starting position, it is no longer legal to castle with that rook.

For example, if white plays 1. a4 2. Ra3 3. Ra1, white can no longer castle long, even though the king and rook are both in their normal positions.

For this reason, the FEN string must encode whether or not castling is legal (because both king and rook can be on the proper squares, but castling can still be illegal).


Full disclosure: I am answering my own question. I recently finished the alpha version of an app that maps chess games to diagrammed positions in chess books (https://www.thechesscite.com/).

The primary goals is to help you to make better choices about what books to buy and to help chess authors cite their colleagues. My other goal is to streamline how you study chess.

See more on the site. I’m still very early in development but have a lot of features planned. Hopefully I’ll see a little interest from the chess community and grow the tool over time. Would be happy to take feedback; however, be aware there are some minor quality of life issues I already know about, and I am a one person team. I'm eager to share this tool even if it's just getting started.


Humans against computers: is it an advantage to humans to have more time or less

Longer time lets both sides to calculate the variants deeper.

In blitz games (< 5 min) computers are terribly strong and we have no chance. Computer's reaction is too fast and it can compute lots of variants in early few seconds. On the other hand humans are potential to make blunders.

In games with 15-60 minutes engines are strong too, but humans have chances to avoid overlooks, obvious mistakes and they can analyze the position better, but yet it's hard to resist against engines.

In long games, engines can discover more variants, the problem is by processing deep variants the state space tree gets huge and finishing depth N and getting into depth N+1 consumes too long time. In other words, if an engine makes its decision after 4 hours thinking on a position, it's rare for it to change its decision to another move by more 1 hour thinking.

On the other hand humans have more time to analyze positions strategically (the only thing that humans are still better than engines. At least it's comparable to engines)

So my answer is long games can give us a better chance to play better against computers.


Will there be any anti-cheating measures that affect the broadcast in the Candidates tournament?

Is it going to be any delay or any other anti-cheating measure that
  affects the broadcasting of the games applied in the Candidates?

It is mostly Agon protecting their commercial rights to the event.

They forbid rebroadcasting and require users / viewers to login and click agreement to a complicated piece of lawyer-speak which is unintelligible to normal people.

Being cynical I expect any delay for other organizations covering the event will come from one of their members subscribing and then playing the moves on a chessboard in front of him so somebody else can broadcast them.

There is no copyright on chess moves or games, only on commentary.


What are openings which were once thought good, but are now shown to be inferior?

Openings tend to go in and out of fashion. At example, the Berlin wall was considered to be very dull and unambitious, but then Kramnik played it against Kasparov to become World Champion. Nowadays the Berlin wall is a regular guest at top tournaments. The same can be said about the Scotch Game, which was rarely seen at the highest tournaments until Kasparov picked it up.

So most of the time when openings are not often seen it is because of fashion. One more important reason is that there may be critical lines that lead to unfavourable situations (like that the opponent can force a draw by repetition). Usually it takes a few years, but then someone comes up with a different idea and the lines are playable again. I remember vaguely a game in the poison pawn variation of the Grunfeld Indian between top 10 players (can't remember who, sorry) that turned the evaluation of the whole line upside down. Such games can kill or revive a line all of a sudden.

More generally, in my opinion there are several phases of the way chess is played. In the early days attack was everything and theory was not well developed, so gambits of all kinds were played (Evans Gambit, King's Gambit,...). I'd call it the romantic phase. Then the scientific phase began with lots of general rules discovered and well researched plans. This led to different opening, more balanced systems becoming the mainstay of tournament play. If you followed the rules of thumb your opening were considered sound. Nowadays we have entered the computerized phase, where concrete variations checked by computers rule the tournament halls. This led to the rise of some very sharp, concrete opening systems that otherwise no-one would have dared to play. So, depending on the time in history your question is asked, you will get a different answer about which opening is a bad choice.


How to combine Basic Strategies to a winning-system

That's not how chess works.

Chess has too many possibilities for a "one size fits all"-strategy or set of strategies that you could learn by heart.

At the risk of repeating myself: Learning chess is like learning a language. It's kind of hard to learn a set of sentences that allow you to win any debate against an average debater.

Instead, "understanding" is the key. Languages and chess have to be learnt the hard way: Maybe some rote learning can be beneficial, but mostly you'll need lots of practice and exposure to "good chess"/correct language until you have developed an intuition about sentence structures/connotations/positions/tactics etc.


The argument needs to point to the Stockfish executable. If you download the v11 zip from the Stockfish website, extract it and find the directories with the executables.
I extracted it to C:\Users\<username>\Downloads\stockfish-11-win
The executables are in C:\Users\<username>\Downloads\stockfish-11-win\Windows

To use the executable, give the path to the executable like so:
from stockfish import Stockfish

stockfish = Stockfish(r'C:\Users\<username>\Downloads\stockfish-11-win\Windows\stockfish_20011801_x64.exe')

The default value for the path you give is "stockfish", so if you add your directory with the executables to the path, and rename the exe you want to stockfish, you should be able to do:
from stockfish import Stockfish

stockfish = Stockfish()

Re. your comment:

no other stockfish related "commands" will work: OSError: [Errno 22] Invalid argument  ... so it seemingly fixed a problem but the next instantly occured.

The ArgumentError is presumably because you're passing a wrong argument. For example, I ran the commands in the readme in the github repository and it works perfectly fine.


Why does Lichess only tell me my "inaccuracies", "mistakes", and "blunders", and not e.g. my "brilliancies"?

It's really hard to tell what a brilliancy is. For example, you might try to say that a brilliancy is a move that's much better than any other move on the board.  Well, if you offer me a queen exchange and I play queen takes queen, you taking back my queen is probably a much better move than any alternative, but it's definitely not a brilliancy. So maybe a brilliancy is a non-obvious move that's much better than any alternative. OK, but what's non-obvious? Maybe you could do something based on the depth you have to go in the search tree to prove that the move is good, but that probably still isn't right because a long sequence of exchanges is usually obvious but, by construction, goes deep into the tree. Or, suppose you trap my queen: by the proof depth metric, that would be a brilliancy if I can insert a long sequence of pointless checks before you take my queen, and a normal move if I can't.

In contrast, bad moves are easy to detect: if a move is suboptimal, you just compare its score against the score of the best move and use a more negative word for bigger differences.

Fundamentally, there's only one best move in any situation. As far as the computer is concerned, you either played it or you didn't.  Bad moves are bad moves, but brilliancies are good moves that most players wouldn't have seen, and that's as much a statement about "most players" as it is about "good moves".


Before consulting a book, try reading the Wikipedia article on rook and pawn endgames.

As you mention, it's a very broad topic.


Why would black resign in this situation?

White gave up two pawns, the g-pawn and the h-pawn, without any compensation. Black's position is objectively winning. So my guess is that black had some non chess reason to resign the game. If this was a blitz game, then perhaps your opponent got a phone call or had to join the dinner table. From a chess point of view, black would have continued this game.


Can one theoretically prove that these moves are marginally better?

You can't really "prove" it. But, presumably, players want to play the best move, so which move is more often played may be an indication of which move the players think is best.
I looked at two databases with master games, and the most popular moves after 1.e4 in each were c5, e5, e6, and c6, in that order. This supports the first half of your statement (since e6 and c6 are played less often than e5 and c5) but not the second half (since c5 is played more than e5.)


Where can I find collections of chess problems (ideally direct mate) with solutions?

TheProblemist.org

  These direct-mate problems are chosen as a challenge to chess players who may be new to the world of composition. You should try to solve each problem before looking at its concealed solution. It may be helpful to look at the commentary or hints before revealing the solution.

Edit:

Chess.com has a great page of 10 puzzles with interactive chessboards. These are 'checkmate in one move' puzzles though, and are very easy.


A game between McDonnell and De La Bourdonnais is very famous. Although no promotion was executed on the board, it is definitely the theme of the game.

      [FEN ""]
      [Event "London m4 ;HCL 18"]
      [Site "16"]
      [Date "1834.??.??"]
      [EventDate "?"]
      [Round "62"]
      [Result "0-1"]
      [White "Alexander McDonnell"]
      [Black "Louis Charles Mahe De La Bourdonnais"]
      [ECO "B32"]
      [WhiteElo "?"]
      [BlackElo "?"]
      [PlyCount "74"]
      [StartPly "74"]

1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 e5 5.Nxc6 bxc6 6.Bc4 Nf6
7.Bg5 Be7 8.Qe2 d5 9.Bxf6 Bxf6 10.Bb3 O-O 11.O-O a5 12.exd5
cxd5 13.Rd1 d4 14.c4 Qb6 15.Bc2 Bb7 16.Nd2 Rae8 17.Ne4 Bd8
18.c5 Qc6 19.f3 Be7 20.Rac1 f5 21.Qc4+ Kh8 22.Ba4 Qh6 23.Bxe8
fxe4 24.c6 exf3 25.Rc2 Qe3+ 26.Kh1 Bc8 27.Bd7 f2 28.Rf1 d3
29.Rc3 Bxd7 30.cxd7 e4 31.Qc8 Bd8 32.Qc4 Qe1 33.Rc1 d2 34.Qc5
Rg8 35.Rd1 e3 36.Qc3 Qxd1 37.Rxd1 e2 0-1


VV is Vorwärtsverteidigung - if a position is retracted into where Black might interfere (by mating White himself ?!), he may. kbP is indeed SPG.
A translation source for many problem chess terms


How can I convert screenshot capture into FEN to analyse on Windows 10+?

This will do it. https://chessvision.ai.
There is also the Chessify app on the ios store where you can take pictures of chessboards and import the position.


Is prophylaxis a feature of the hypermodern school?

It's because Nimzowitch  was the foremost figure amongst the hypermoderns, you can't mention hypermodern school without Nimzowitch. And the prophylaxis idea first introduced by him, in his famous book Mein System. If we would call him the father of modern chess, it wouldn't be wrong.

His ideas was challenging the dogmatic rules set by Tarrasch, which widely considered as the best strategy at the time.

There is an excellent book named Secrets of Modern Chess Strategy: Advances since Nimzowitch, which covers prophylaxis and lot more. I recommend you to read it.


Why is g4 the best move in this Queens Gambit accepted line?

I suppose you have some source that claims 1.g4 is the best move from the diagram position, but which doesn't give any reason for it. I won't try to weigh in on whether it is in fact the best move here, but I will try to articulate a reason or two to play it. First I'll say that I don't think it's the tempo against the bishop that offsets the decreased king safety, but rather other tangible results instead.

To my eye, the primary point in its favor is that White gets one of two potentially desirable outcomes immediately: either (1) Black moves her bishop away from controlling e4, so White gets in the move 2.e4 next, building a nice central pawn duo, or (2) Black responds with 1...Be4, and allows a forcing line that lets White obtain two minor pieces for rook and pawn. (I'll note that my first thought in responding to 1...Be4 was simply to win the bishop pair for White, but that ultimately doesn't look that great, and it was some nudging from Stockfish that revealed this other idea to me.)

The annotations that follow look at these two resulting possibilities in a little bit of detail, offering my scant takes on matters. But I'll note that there are a lot of concrete, tactical ideas in the air here, and the overall situation is more chaotic than I initially thought when first looking at the position.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "r2q1rk1/1pp1ppbp/p1n2np1/5b2/P1BP4/2N1PN1P/1P3PP1/R1BQ1RK1 w - - 0 1"]

1.g4
    {Lessening Black's control of the e4 square by putting the question to
    the bishop.}
1...Bd7
    ( 1...Be4 {Trying to stop White's central expansion, but it allows
    White to force the obtaining of two pieces for a rook and pawn if he
    so chooses.} 2.Nd2 $1 Bd5 {Forced.} 3.g5 $1 Bxc4 {Forced,} 4.gxf6 Bxf1
    {Forced.} 5.fxg7 Kxg7 6.Kxf1 {White's larger piece army offers the
    better prospects, and the airy castle around his king isn't an
    immediate concern, and with proper play shouldn't be an issue.} )
2.e4
    {Establishing an ideal pawn center, though yes at the expense of
    having created a good deal of space around the white king. In fact,
    Black can (and perhaps should) now sacrifice a piece for pawns and
    greater exposure of the white king.}
2...Nxg4
    ( 2...h5 {Another attempt to further expose the white king.} 3.e5 {
    This basically forces Black to go in for the same sort of piece
    sacrifice as in the 2.e4 Nxg4 line given here.}
        ( 3.Nh4 $5 {Another interesting possibility, exploiting the fact
        that the only non-pinned pawn defending g6 has now advanced.} 3...
        hxg4 $2 4.Nxg6 )
    3...hxg4
        ( 3...Nh7 $2 4.gxh5 gxh5 5.Kh2 {Now the white king is no more
        exposed than the black king, and White will be the one with the
        better attack.} )
    4.exf6 Bxf6 5.hxg4 Bxg4 6.Qd3 {Threatening Qxg6. Again I'd wager that
    White's extra piece outweighs the deficit in pawns and the exposed
    king.} )
3.hxg4 Bxg4 4.Be2 Bxf3 5.Bxf3 Nxd4 6.Bg2
    {Black has three pawns for the piece, and has removed much of the
    white king's pawn cover. Nevertheless, Black does not have an
    attacking force at the ready immediately, and I think the long term
    chances should favor White's extra piece.}
*


In Bughouse can you claim a draw if the position on the board repeated three times but the pieces available to place were different?

Not having a governing body for bughouse, the rules are a little informal.

Per the Wikipedia article:

  Depending on (local) rules threefold repetition applies, in which case
  the reserve of pieces is not taken into account.

If you think about it, if the available pieces were taken into account, first, with no scoresheet, it would be really hard to prove, especially at a typically fast time control; and second, the simple mathematical possibilities would probably render any chances of a draw virtually impossible.

So basically, if the house rules allow for a three-fold repetition, it probably has to be just considering what is on the board of just one of the two boards.

So to answer the base question, most people probably play by those rules, and thus, the answer would be "yes, you can claim a draw under those circumstances".


The source code for SmallChess is not available as it is closed source. The link for the source code is for SmallFish.

If you still want the source code you might have to wait, as neither does Google have that page cached nor does The Wayback Machine.


How did a pawn appear out of thin air in “P @ e2” after queen capture?

You were playing the chess variant called Crazyhouse. In this variant you can place pieces you captured, as one of your color anywhere on the board, instead of a normal move.
I don't know the software you are using, but on Lichess the variant can be selected in the "Create a game" dialog. There should be something similar in your application.


Is there a way on lichess to see the Correspondence chess rankings?

It is funny that they do not have it listed here, as you mentioned.

I just took a guess, and changed the end of the URL to "correspondence", and got the top 200 just like the others.

https://lichess.org/player/top/200/correspondence


Why can Stockfish give different evaluations at the same depth?

If Stockfish was a pure minimax/alpha-beta searcher with all leaves having a predetermined depth, your assumption that the search result should be reproducible would hold true, even with a different state of the hash table. That is because the result in minimax/alpha-beta only depends on the evaluation function, but not on the order in which the moves are searched, which only has an impact on speed.

However, in fact Stockfish is using a lot of forward pruning, reduction and extension techniques that are state/history dependent, so the results of the search of a subtree depends on the state/history with which it entered the subtree. Therefore, starting with hash table entries that influence move ordering (and can actually return a different evaluation than searching the subtree again) leads to a different result of for a search of same depth.

There is one more detail in the Stockfish case why even with pure alpha-beta search re-searching the position again would give different results. The evaluation of draws is pseudo-randomized with small fluctuation from zero in order to avoid some search artefacts in case of repetition draws, and this pseudo-random number depends on the node count of the current search. Therefore, using a different move ordering due to the hash entries would lead to different pseudo-random numbers, and hence potentially a different search result.


What do DTM, DTZ, DTC, DTR, DTZ50, and DTZR mean?

In various endgame tablebases, the terms mean as follows:

Depth to Mate.   For each position that is represented, 'DTM' indicates the theoretical value, and the number of winner's moves to 'Mate' if won/lost - assuming that the winner is minimizing and the loser is maximizing DTM.

DTC
Depth to Conversion 'Conversion' is the changing of the force on the board, by capture and/or Pawn-conversion. For each position that is represented, 'DTC' indicates the theoretical value, and the number of winner's moves to the goal of 'Won Conversion' if won/lost - assuming that the winner is minimizing and the loser is maximizing DTC.

DTZ
Depth to Zeroing (of the ply count) The ply-count is zeroed if and only if a Pawn is pushed or a capture is made. For each position that is represented, 'DTZ' indicates the theoretical value, and the number of winner's moves to the goal of 'Win and ply-count zeroed' if won/lost - assuming that the winner is minimizing and the loser is maximizing DTZ.

DTZ50
Depth to Zeroing (of the ply count) in the context of the 50-Move Rule The DTC, DTM and DTZ metrics do not consider the current FIDE 50-move rule whereby a game in which no irreversible moves have been played for 100 plies can be claimed as a draw by the player 'on move'.

DTR
Depth by the (k-move) Rule 'The Rule' referred to here is a notional set of k-move rules. For each position that is represented, 'DTR' indicates the theoretical value and, for won/lost positions, the least k for which DTZk is not draw - assuming that the winner is minimising and the loser is maximising DTR.

DTZR
Depth to Zeroing move, give that DTR is being minimaxed If DTR = draw, then DTZR = draw. Otherwise, Otherwise DTRZR indicates the theoretical value, and the number of winner's moves to the zeroing of the ply count, given that the two sides are minimaxing first DTR and then DTZR.

DTZR would be used in conjunction with DTR to progress a deep win in the context of a k-move rule because DTR can remain unchanged over a sequence of moves.


Not exactly sure what you're after with that question, but here's something to at least open the ground a little.
The "Greek Gift" I think is more a name for a particular sacrifice than a theme. It employs a couple of themes, e.g., line clearance and decoy -- line clearance opens a hole in the castled position for other pieces to use for attacks, and decoy brings the enemy king to a square where it can more easily be attacked. Another famous sacrifice using those themes is Lasker-Bauer (Lasker's double bishop sacrifice).
There are numerous resources covering tactical themes, going back to Spielmann's "The Art of Sacrifice In Chess" but a couple of the best resources for mating themes and patterns are Renaud & Kahn's "Art Of The Checkmate" and Vukovic's "The Art of Attack in Chess" (of the two I'd prefer the latter only because it covers more than just checkmates, but all three books are well worth the time to study them).
In Vukovic's book, chapters 4 & 5 deal in general with your question of checkmating themes. As for the "Greek Gift" itself, he spends chapter 6 specifically on that sacrifice. Eugene Znosko-Borovsky in "The Art of Chess Combination" spends a chapter on it (and another on Lasker's double-bishop sacrifice) and Former US Correspondence Champion Jon Edwards devoted an entire book to it (Sacking The Citadel).


Are today's top correspondence chess players stronger than those from 5 years ago?

Yes, mainly due to more advanced theory that wasn't known five (or more) years ago.

Also, while top Correspondence players do indeed combine engines with their own ideas, having an Engine that is a few hundred rating points higher is a definite factor. I find it hard to believe the person you quoted uses the same engine he has for 10 years. If he means the same computer though (so running the most recent Stockfish/Komodo/Houdini on an old computer), that sounds more understandable. In this case he's only sacrificing the amount of speed that a PC 10 years older gives up compared to PCs now.


To what extent should you prevent your opponent from castling?

Can you try answering why are you trying to prevent your opponent from castling?

When you think about this more - you realize that castling prevention is just a tactical weapon, nothing more. Of course you can win a game if you are good at tactics, if your opponent makes mistakes, but, to quote Alekhine:

  "It took me many years to get rid of the bias that I can win in any
  position, even in a bad one, using some amazing combination".

The need for playing to prevent your opponent from castling is dictated by the position on the board. Of course it makes sense to follow this plan if you achieved some development advantage in the beginning of the game, your pieces are more active and you have good chances to start a massive attack against the enemy king that's trapped in the middle. Of course, sacrificing a pawn (or even more pieces) in this case is justified, since your positional advantage will compensate that.

What if you can't prevent your opponent from doing multiple exchanges after you sacrificed a pawn? Losing many active pieces (due to exchanges) will reduce your attacking potential. And you will have to play an endgame without a pawn. If your opponent is better than you at endgame - he will force those exchanges with the endgame in mind - entering it in a better (or even won) position. Since he will have at least two advantages over you:

+1 pawn
king in the middle (assuming you castled), which is considered an advantage in endgame

This is very important to consider, since often even a single exchange (of queens) serves as green light to endgame.


Where can I find mobile software for Fischer random chess?

There are a number of websites and tools listed on the Chess960 wikipedia page. Scroll to the bottom for the complete list. These should all be playable on your mobile device.

http://en.lichess.org/
http://www.chesshotel.com/play-random-chess.php
http://www.mychess.de/


In the opening stage, can we determine that one move is better than another by looking at winning percentage?

The precise answer depends largely on the database, and the answer is still never yes.

If the database includes any players below 2500ish OR it includes blitz or rapid time controls, do NOT attempt to rely on these percentages. Inaccurate moves were likely played and possibly "moved to the top" of the possible moves.

You could possibly rely on percentages for main lines with high rated players and long games, but it's still a little risky.

I would recommend looking instead at established opening theory books/websites as well as Stockfish.


Remember what a rating is: it's an estimate of the relative strengths of the players. The more information you include in your rating calculation, the more accurate it will be and the faster it will converge. At the end of an OTB game, the only new information you have is the result of that game. However, on a correspondence site, you also have the information from both players' results while the game was in progress. Why would you not want to use that information?

To update the players' ratings based on their ratings at the start of the game is to say that you think their ratings at the start of the game are a better estimate of their relative strength than their ratings at the end of the game. In other words, it's saying that you believe the ratings are becoming less accurate with time. If that's what you believe, you shouldn't update them at all!


Bughouse chess tournament pairing software?

There is no pairing program which can do what you want. No program exists to change the partners every round according to the previous results. Pairing programs also try and avoid pairing players or teams which have played before.

Exactly how the partners would vary and how you would decide who had played whom is not clearly defined in your system. Your idea needs more work.


A conditional retrograde analysis problem

The solution is as follows:

   1.e4 Nf6 2.f3 Nxe4 3.Qe2 Ng3 4.Qxe7+ Qxe7+ 5.Kf2 Nxh1#


In the case of en passant, should I move my pawn first or remove my opponent's one?

Both methods are legal. There is, however, one difference between the two options. If the en passant turns out to be illegal, then you must make a move involving the first piece you touched, if it is legal to so.

So, if you touch the opponent's pawn first, you must capture the opponent's pawn. If you touch your own pawn first, you must move your own pawn.

I can't say I know which is preferred by grandmasters. But it seems like moving your own pawn first is somewhat less likely to result in disaster if the move turns out to be illegal-imagine having to capture a defended pawn with your queen.


Novice - Capitalizing on players not knowing their openings?

I think your problem comes from the difference between memorizing the opening theory, and understanding it. I suggest you focus more on understanding, why this move is played (both yours and theirs). This way, you can think during the game, why this move could be not optimal and play accordingly. Even if you do not know, how to take advantage of it, you can it least follow the theme of your opening.

To understand the theme of an opening, you can (most of the times) read books about it. The introduction will contain the goals of the opening most of the times. You can also just take a chess board and look for yourself, what the lines of the openings are about.

To understand the reasons behind the moves, just play out different moves, which look natural to you. I recommand not to use an engine at first, and only check afterwards, if you missed something. Do not memorize every line, but rather look for common motives, which appear, e.g. they do not defend a field, so now you can put your knight there which puts pressure on a crucial field. Or they trade DSB, so now they have a weakness on dark squares (if pawns are on light squares), so you can try to capitalize on that.

My personal experience however is, that at your level (and some levels above) gaining minimal advantages through the opening is not so important. A lot of games will be decided by tactics, so remember to constantly look out for them!


What is the name of this Sicilian Variation?

It's an old main line of Sicilian Najdorf, and according to Wikipedia, it's the De Verbeterde List, or Improved Strategem, due to recent efforts by Dutch players to revive it.


1. Kxh2 allows Black a forcing sequence exchanging off the pieces and White loses his big advantage: 1... Qh6+ 2. Kg2 now Black can capture the Rook on f5 and force a trade of queens: 2... gxf5 3. Qxe5+ Qg7+.


Games that are famous because of their underlying story

Bobby Fischer's games in the 1965 Capablanca Memorial gained fame because he was denied a visa to travel to Cuba, and was the only player in the tournament who had to play all of his games from New York by telephone.  It was especially grueling because those games typically lasted 8 hours or more due to the communications lag.


How did I overperform in this rapid tournament?

There is a game theory of why 1st round NFL drafts don't perform as well as expected.  The reasoning is that the player had an above average couple of games and returned to his average performance.  By the same logic, there are later round drafts who have stellar careers.

I'm not going to make a judgement based on three games, or even your archive on lichess.org, as this would be as effective as making a prediction based upon your avatar.  I would say that guess that this tournament was lucky for you (assuming that your not a teenager who just improved naturally), but that, just by experience alone, you could achieve an 1800 rating on lichess.org at any time control.

EDIT:
Stacia Pugh (https://www.youtube.com/channel/UCn2k14U03rNRHApDIloxOkA) is a chess example.  She started off well and achieved a peak rating of 1791.  This can be considered a fluke as she quickly dropped to her floor rating.  She's still a good player and is trying to improve.


Public higher-order endgame tablebases for *common* positions?

I understand where you are getting from. Unfortunately, it doesn't quite work like that. To generate a 7-man KRPPvKRP you would also need 7-man endgames for the promotion. You would need:

KRQPvKRP
KRQPvKRQ
KRQQvKRQ
KRBBvKRB
.......

Can you see, it's really not that easy to generate an endgame with a pawn, because that can transpose to another endgame with the same number of pieces.

We do have technology to generate Syzygy 7-piece, but you'd need a super-computer or a high-performance-computing to do it. Google can definitely do it if they want to. So far, nobody wants to cover the costs.


There are several reasons why someone would use the term 'master', but without a specific reference to work from all I can suggest is that the term is generally synonymous with the phrase 'top player'. The two examples that come to mind are:

Historical: Many of the great early players did not have actual titles (either because the titles had not been invented or because the systems for reliably attaining them had not been introduced). In this case, one might refer to Morphy or Philidor as a 'master', simply because calling them a GM/IM would be inaccurate. Also consider that when the title 'Grand Master' was first conferred, it was not just a title to hand out to players but a real statement that those five players were some of the best ever.
Cultural: As you noted in the question, many foreign (esp. Russian) books up until the 1980s or so use the term. I cannot say exactly why, but the usage is certainly meant to indicate that those people are deserving of respect as top-calibre players. Perhaps part of this is due to the fact that some top theoreticians were not acknowledged as being among the best practical players, and so this allowed them to be given the same level of respect as determined by the author. Hopefully someone more knowledgable in soviet chess culture can fill us in on this one.

This is in contrast to the modern USCF system where a range of various master titles are (by comparison to earlier times and other areas of the world) given out like candy. This is not to say that the achievements are not still somewhat impressive, but they ultimately mean something much less than the term does in those other contexts.


Least number of moves to achieve a complete switchover of nonpawns in starting setup

As @chakerian's calculations show, 40 moves is the minimum. After a bit of puzzling, I found the solution.
[FEN ""]

1. a4 {First, we need to get the rooks in position. They'll be hard to swap once the board is full.} a5 2. h4 h5 3. Rh3 Rh6 4. Rg3 Rf6 5. Rg6 Rf3 6. Rh6 Rh3 7. Ra3 Ra6 8. Rc3 Rb6 9. Rcc6 Rbb3 10. Ra6 Ra3 {Now, we can start with the knights. They're tricky because they need to swap places via the four center squares. Note that we cannot move the center pawns *before* the knights.} 11. Nf3 Nc6 12. Ne5 Nd4 13. Nc6 Nf6 14. Nc3 Nd5 15. Ne4 Nc3 {It's time for the kings to come out of their hiding, but they have do this carefully because of the knights.} 16. Rh8 d5 17. Ra8 Kd7 18. Nf6+ Kd6 19. e4 Ra1 20. Ba6 b5 21. Nb8 Kc5 {The black monarch chooses queenside - that means his colleague has to take the other one.} 22. Ng8 Nde2 23. d4+ Kc4 24. Kd2 Rh1 25. Ke3 Ng1 26. Kf4 Bh3 27. g4 f5 28. Kg5 e5+ 29. Kg6 Bf1 30. Bh6 {Note how the c1-h6 and a3-f8 diagonals have been left open for the transfer of the last four pieces.} Qg5+ 31. Kf7 Ba3 32. Ke8 Qc1 33. Qd2 Nb1 34. Qg5 {OK, we're almost there now, from here it's a walk in the park.} Qd1 35. b4 Kc3 36. Qd8 g5 37. Bf8 c5 38. Bc8 Kd2 39. c4 Bc1 40. f4 Ke1 {And we're done!}

To answer the second question: you're looking for the longest unique proof game. I found the longest known one here and here.
[Title "Dmitri W. Pronkin & Andriy Frolkin, Die Schwalbe 06/1989, 1st Prize, PG in 57.5"]
[FEN ""]

1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 5. h4 d5 6. h5 d4 7. h6 d3 8. h7 dxc2 9. d4 a5 10. Bh6 c1=R 11. e4 Rc5 12. Ne2 Rh5 13. e5 c5 14. e6 Nc6 15. b8=R a4 16. Rb4 a3 17. Ra4 c4 18. b4 c3 19. b5 c2 20. b6 c1=R 21. b7 Rc4 22. b8=R Qa5+ 23. Rbb4 Bb7 24. N1c3 O-O-O 25. exf7 e5 26. Rc1 Bc5 27. f8=R a2 28. Rf3 a1=R 29. Na2 g1=R 30. Rfa3 Rg6 31. f4 Re6 32. f5 g5 33. f6 g4 34. f7 g3 35. f8=R g2 36. Rf5 g1=R 37. Bf8 Rg7 38. Ng3 e4 39. Bd3 e3 40. O-O e2 41. Rcc3 e1=R 42. Bc2 R1e3 43. d5 Rdd7 44. d6 Rdf7 45. d7+ Kb8 46. Qd6+ Ka8 47. Qc7 Nge7 48. d8=R+ Nc8 49. Rdd3 Rhg8 50. h8=R Rae1 51. Rh6 R1e2 52. R1f2 Rce4 53. Kf1 Bd4 54. Rfc5 Ne5 55. Nf5 Nc4 56. Nd6 Nb2 57. Rbc4 Nb6 58. Qb8+

What this really means, is that the final position can be reached in 57.5 moves (not less), and that there is only one way to do this. In your example, moves 48 and 49 (and many others) could be switched. Also, currently there is no other position with this characteristic known which takes more moves to obtain.


How to check mistakes, blunders and missed wins on Chess.com?

Click on view analysis or computer analysis button


Building up a dataset for image recognition of hand-written scoresheets

Does anybody have a (larger) body of scoresheet images + respective
PGNs or knows which persons/entities could potentially provide those?

All FIDE rated tournaments where norms are available (so must have a minimum number of GMs, IMs and federations playing in the tournament) are required to submit PGNs of games played to FIDE to ensure the integrity of titles. This means that all such tournaments will have a stack of scoresheets which have to be entered into the computer and submitted to FIDE. This means that arbiters at such tournaments who have responsibility for inputting are likely to have large numbers of such scoresheets.
Aside: As somebody who has been the chief arbiter in a norm tournament I can tell you that such a program, if successful, would be very, very welcome.
Additionally some federations, leagues and tournaments have policies of trying to submit PGNs for FIDE rated tournaments where norms are not available. The English Chess Federation is one such and in it the 4NCL (4 nations chess league) are very good at publishing PGNs.
Entering scoresheets into the computer is often difficult and can be boring. Some people (me, for instance) are not that good at processing a stack of, say, 100 scoresheets. Other people are very good indeed. In England there is one star who is quite brilliant. That is International Arbiter and IM Jack Rudd. I don't know what he does with scoresheets after he is finished but if he doesn't throw them away he will likely have a very large pile. You will see him on the list of arbiters officiating at mega tournaments like Gibraltar and Isle of Man because he is so good at this.
To be useful your program will need to handle languages other than English, including languages which are written from right-to-left like Arabic, Hebrew and Thai.
I should add that arbiters are not particularly strict when it comes to enforcing rules around scoresheet legibility and entering the moves correctly. For instance, although the abbreviations for the pieces may be in your native language, the files must be written in English ("a" through "h") however many players use their own alphabets for these and I don't think I have ever come across an arbiter who enforces this.
Finally, here are a couple of scoresheets from a tournament where I was chief arbiter a few years ago.

Surprisingly this is one of the more legible scoresheets from this player. He did, though, use descriptive rather than algebraic notation.
Here is a more legal one (algebraic)

I wish you a lot of luck with your project but I don't think you really understand the problem. Playing chess can generate very high levels of stress in the players and this often leads to problems with how they write the moves.
PS You can download the pgn file for the tournament these games came from from the FIDE website here.


How do you hold a draw with a bishop against a rook?

INTRODUCTORY NOTE:

Examples and instructions are taken from the book:

Y.Averbakh - Comprehensive Chess Endings Volume 2.

RELEVANT POSITIONS FOR PLAYING THIS ENDGAME SUCCESSFULLY:

I will quote the introduction from the above book:

"It is impossible to win against correct defense, even if the defender's king is driven back to the edge of the board. When retreating under the pressure of the opposing pieces, all he must do is to reach the corner of the opposite color to the bishop. We will call this the safe corner".

[Title "Weaker side holds balance"]
[fen "7k/R7/7K/8/8/1b6/8/8 w - - 0 1"]

1.Ra8+ Bg8=

White can't improve his position, since moving his king or moving rook along the 8th row will lead to stalemate. Black maintains balance by keeping his bishop on a2-g8 diagonal.

Again, quoting the same resource:

"If the defender's king is in a corner of the same color as his bishop, a win is normally possible. We will correspondingly call this the dangerous corner."

The following position demonstrates winning method when weaker side has king in "the dangerous corner":

[Title "Horwitz & Kling, 1851"]
[StartFlipped "0"]
[fen "6k1/5R2/6K1/8/3b4/8/8/8 b - - 0 1"]

1...Bg1! ( 1...Bc5 2.Rc7 Bf8 3.Rc8+-) 2.Rf1 Bh2! 3.Rf2 Bg3 4.Rg2! Be5 ( 4...Bh4 5.Kh5++- ) ( 4...Bd6 5.Rd2 Be7 6.Rc2!+- ) 5.Re2 Bd6 6.Re8+ Bf8 7.Rd8+-

Black must hide his bishop as in the main line, and we saw how to flush it out and win. The sub-variation shows what happens when he refuses to do so.

Here is another important position, where the result depends on who's turn to move is:

[Title "Horwitz & Kling, 1851"]
[fen "5k2/6R1/5K2/8/8/5b2/8/8 w - - 0 1"]

With the kings in opposition mating threats are in the air and if White moves first he is able to win. For the moment bishop is hiding behind the opposing king, but with the above rook maneuver White can flush it out:

[Title "Horwitz & Kling, 1851"]
[fen "5k2/6R1/5K2/8/8/5b2/8/8 w - - 0 1"]

1.Rg3 Be4 ( 1...Bh5 2.Rh3 Bf7 3.Rh8+ Bg8 4.Kg6+- ) ( 1...Bc6 2.Rc3 Bd7 3.Rb3! Kg8 4.Rb8+ Kh7 5.Rb7+- ) 2.Re3 Bg2 3.Re2! Bf3 4.Rf2+-

But if it is Blacks turn to move he saves the game by running with his king:

[Title "Horwitz & Kling, 1851"]
[StartFlipped "0"]
[fen "5k2/6R1/5K2/8/8/5b2/8/8 b - - 0 1"]

1...Ke8! 2.Ke6 Kd8 3.Kd6 Kc8=

Since the c6 square is inaccessible to the White king he is unable to make any mate threats.

These are the basic positions required to know in order to play this endgame well.

In the above book were provided studies which were complex, but can be solved with the knowledge of the above covered positions.

To keep this post clear, concise and useful I will omit them.

Best regards.