How do you convert a scid database into a pgn database?

Go to the Tools menu and somewhere down you will find under the option Export Current Game the option Export All Filter Games. In this sub-menu there is the option to export them as PGN.


What happened in the game Draskovic - Sutovsky (EICC 2015)?

chess-results.com says the result was a draw. I wonder if it was one of those DGT errors where an incorrect result is reported due to the position of the kings.


In the first half of the XXth century, French and English were the main international languages.

During and immediately after the first congress in Paris, 1924, the French acronym for "Fédération Internationale des Echecs" was actually FIE, and it was referred in the English-speaking world as "International Chess Federation" or ICF. But already the following year, at the Congress in Zurich, French-speaking members (and possibly Italy) made a point that "fide" meant "trust" in Latin, thus the 'D' was added for the name to symbolize the confidence of its members in the institution, and FIDE became the official acronym in both languages (and worldwide).

E.Winter's Chess Notes have a very interesting article about the birth of FIDE:

  ‘FIDE was founded in 1924’ say the history books, yet, technically speaking, that could be disputed. Certainly the Fédération Internationale des Echecs was formed that year, but its Statutes systematically referred to it as ‘FIE’, and not ‘FIDE’:

But it doesn't give the reason of the later change:

  But later in the year, for reasons as yet unclarified, ‘FIDE’ became the official acronym. If ‘FIDE’ appeared in print in 1924, we have yet to find it.

I remember reading that the Latin meaning was the motivation for switching to "FIDE" in some chess-history book in French, but I will have to dig further to source it properly.


Game databases vs. various languages/character sets

You don't need good English to play chess...

  https://tieba.baidu.com/p/5369964903

is Baidu (China's larger search engine) page on chess.

Do you see? The Chinese know Nxf2, Qxe3+, Bg3.

The Chinese players don't need a new software because they can use Chinese in a chess software.

In the screenshot, I have Mikhail Botvinnik in Chinese in my ScidVsPC software.


If you add the --quiet option that should do it:

FEN=$(echo "1.d4 Nf6 2.Nf3 e6 3. *" | pgn-extract -F --quiet)

kentdjb (author of pgn-extract)


How do I increase my chances to win as black in the Ruy Lopez?

The Ruy Lopez is probably one of the most analyzed openings in chess. You can find plenty of resources on the Internet. (Wikipedia's article on the Ruy Lopez is a good point to start).

I would recommend that you not go searching for "winning lines". You first need to understand the principles that lie behind each move of this opening. Once you have that understanding it is easier to examine variations and choose the one that best suits your needs.

For example, if you are an aggressive player and your chess level is average, you might wish to consider the Open Defense and the Marshall Attack.


Chess software that can show all legal moves?

I believe most sophisticated GUI would have the feature to:

highlight possible moves for any piece; i.e. if you click (or hover) on a piece it will highlight all possible destination squares
highlight attacked pieces
highlight the last move

Arena and chesspad and many others should be able to do this.

Showing all possible moves is not useful as there are far too many in most positions, that you would not see anything anyway.

If you want to play online, also the lichess client (and probably others) can highlight moves.


Solving atomic chess is probably only feasible if it is a white win, like loser chess is.
To try to solve atomic chess I would probably write/acquire a strong atomic engine first.
Then you build a tree starting from the starting position. If it's white to move you chose only one move, if it is black to move you try all possible moves. The engine evalution will guide you in which white move to chose and which black moves should be investigated deepest.
Basically I would try to build a tree that has leaves with a certain minimum positive evaluation. This way you always have a form of very weak solution of atomic chess, i.e. a tree that tells you how to play with white to get an advantage of at least +x.yz.
You'll try to improve x.yz by analysing those parts of the tree where the leaves have the lowest evaluation. If x.yz gets high enough you can try to work positions out until mate (probably you'll need some tablebases at that point).
If you start this kind of project you probably quickly get an impression, whether getting a significant white advantage is generally easy or difficult, which might be a pointer to whether it is ultimately solvable or not.
This is pretty similar to building a repertoire, so I would probably quick start the tree with an existing atomic chess repertoire.
Of course odds are that your tree will never converge towards a strong solution, but in that case at least you've created a really nice atomic repertoire.


I don't know of any books that follow the format that Yusupov uses in his series.

The Soviet Chess Primer by Ilya Maizelis, and Journey to the Chess Kingdom by Averbakh and Beilin are both good initial books. The Complete Idiot's Guide to Chess by Patrick Wolff is also a nice book.

There are also series of books, such as Yasser Seirawan's Winning Chess ... series, and Lev Alburt's books.


Carlsen-Anand, Game 2. Could Black hold if not for 34...h5?

Anand could have chosen

[fen "5rk1/4R1pp/3q1p2/p1p2P2/P3Q2P/5p2/2P2PPK/8 w - - 0 1"]
[Event "WCC"]
[Site "Sochi"]
[Date "2014.11.09"]
[Round "2"]
[White "Magnus Carlsen"]
[Black "Viswanathan Anand"]
[Result "1-0"]

1.g3 Qd2 2.Qxf3 Qxc2 3.Kg2

After which we reach a Queen+Rook middlegame. In such middlegames, the following factors are critical:

King safety
Piece harmony (coordination and collaboration between the Queen and Rook)

My evaluation of the position above is as follows. Black's King is less safe, since the f-pawn is on f6, exposing the seventh rank for the white Re7 and making it possible for white to attack the g7-square. Further, the white Re7 is better placed than the black Rf8. The white Qf3 is controlling the h1-a8 diagonal, safe guarding the white Kg2 as well as threatening Qf3-g4, Qf3-d5 and Qf3-b7.

White can have the following strategy: use the better King safety and harmony to attack the enemy King and checkmate and/or win material along the way.

Black can have the following strategy: keep the pieces active, try to make them collaborate better, seek a counter attack on the enemy King, try to exchange queens.

I think the position is better for white yet black can still fight. For example

[fen "5rk1/4R1pp/3q1p2/p1p2P2/P3Q2P/5p2/2P2PPK/8 w - - 0 1"]
[Event "WCC"]
[Site "Sochi"]
[Date "2014.11.09"]
[Round "2"]
[White "Magnus Carlsen"]
[Black "Viswanathan Anand"]
[Result "1-0"]

1.g3 Qd2 2.Qxf3 (2.Qe6+ Kh8 3.Qf7 Qxf2+ 4.Kh3 Qf1+ 5.Kg4 h5+ 6.Qxh5+ Kg8=) Qxc2 3.Kg2 Kh8 4.Qg4 (4.Qb7 Qxf5 5.Rxg7 Rd8) Rg8

Conclusion from the position after 1...Qd2:

[fen "5rk1/4R1pp/3q1p2/p1p2P2/P3Q2P/5p2/2P2PPK/8 w - - 0 1"]
[Event "WCC"]
[Site "Sochi"]
[Date "2014.11.09"]
[Round "2"]
[White "Magnus Carlsen"]
[Black "Viswanathan Anand"]
[Result "1-0"]

1.g3 Qd2

Black should play Kg8-h8, Rf8-g8 and h7-h6 to secure the kingside.
Black should trade all the pawns on the queenside and play 3 against 4 on the kingside.
White should try to prevent this from happening.


AlphaZero and the revenge of the Artificial Intelligence

Pretty much everybody. The reason being that it is STILL slower. The evaluation function for alphazero has WAY more variables so despite more computing power, alphazero can only calculate a fraction of number of positions than stockfish. However the evaluation function for alphazero is much much better due to self-learning and also takes forever to calculate.

https://arxiv.org/pdf/1712.01815.pdf

Consider this. Google used 5000 super computers to train the AI to play before the game. Now consider what happens if you give stockfish access to 5000 super computers to think for 4 hours and if it memorized all those lines.

The issue comes down to computing power.
Not in your lifetime.

It is a bit difficult to find Ghz to tflop conversions but consider this.

https://www.pugetsystems.com/labs/hpc/Intel-Core-i9-7900X-and-7980XE-Skylake-X-Linux-Linpack-Performance-1059/

28 cores on 2.6Ghz gives about 1.123Tflops. So for 88 cores running at 2.2Ghz each is around 3Tflops. So your system gives around 3Tflops.

Now I can't find any information on the first generation TPUS but the second generation TPUs have 180 Tflops each.

https://en.wikipedia.org/wiki/Tensor_processing_unit

So 1 TPU = 60 of your systems. So 5000*60*4 = 1200000 hours = 136 years.

Also should clearly show how unfair the alphazero vs stockfish match is.

Edit: I made a mistake, you said 2 22 core systems. My calculations had 88 cores. So you would need to double the previous total to 272 years.


Can the King be put in Check by a piece that cannot move?

No, the black king cannot capture the rook in the position. The simple explanation is that the white knight will capture your king before your rook captures your opponents king. Personally, chess should not have rules such as check and checkmate. The aim of the game should be to capture the king, not checkmate the king. I speculate that these rules of checking and checkmate was formed by etiquette anyways since even in Xiang qi where the object is to capture the "king," you still say check, and I learn that it was a convention of etiquette. .


My strong SmallChess iOS app. Multi-lines is supported:

You can also try each variation on a variation board:


Other than Fairy-Max, is there a variant [fairy] chess engine that is compatible with XBoard?

The XBoard Alien GUI is reputedly better suited to playing chess variants than the standard XBoard is, but that's just an observation. There are many engines that play only a few variants.
     Here's a list of engines (other than Fairy-Max) that have been noted as playing a large selection of variants and working with XBoard (Linux environment being implicit):

ChessV (plays over 50 variants)
Nebiyu Alien (a score of variants tested in homepage; many additional [user defined] .ini files available as a collective package or individually)
Pulsar
Sjaak II (Glebbeek's, not de Man's)
SMIRF


If black plays the triangle system againts the Queen's Gambit, white can (try to) transpose to the Semi-Slav defence: 1.d4 d5 2.c4 e6 3.Nc3 c6 4.e3 Nf6 5.Nf3 Nbd7.

The line 6.Bd3 dxc4 7.Bxc4 b5 is called the Meran. White can avoid this, by playing the Anti-Meran: 6.Qc2. A good summary can be found on Wikipedia.

According to the Game Database of ChessTempo, 4....Nf6 and 5....Nbd7 are by far the most popular replies for black. The Semi-Slav is known to be a good and solid defence.

An alternative for black is 5....a6, which was played many times by Anand in his WCC-match against Gelfand.

An other idea is to transpose to the Stonewall. You can play 4....f5 immediately or wait a couple of moves like in the game Kasimdzhanov-Grischuk.

      [FEN ""]
      [StartPly "7"]

      1.d4 d5 2.c4 e6 3.Nc3 c6 4.e3 Nf6 (4...f5)(4...Nd7 5.Qc2 Nh6 6.Bd2 f5) 5.Nf3 Nbd7 (5...a6) 6.Bd3 (6.Qc2) dxc4 7.Bxc4 b5


Minimum sets of pieces required for checkmate?

King + Bishop + Knight
King + Bishop + Bishop
King + Rook
King + Queen
and don't forget the unlikely King + Knight + Knight + Knight

Assuming the lone King is attempting to avoid checkmate.


Does three-player chess have any special tactics I should know about?

Well, since an exchange between A and B is in the sole benefit of player C, your primary objective should be: avoid exchanges. How do you avoid exchanges in a normal chess game? Play an opening with a closed center (e.g. King's Indian, Ruy Lopez), or choose a modest setup (like the Hedgehog system). The less you're exposed, the better.


Identifying principles and thought processes to use in locating a +3.2 or similar move

This position is more complicated than it first looks!  You need to see more than one move deep to understand the difference between 15...Rxd1 and other moves.
As Scounged has pointed out, you already have an advantage of about +3 because you're a piece up.  The problem is that white is attacking your pawn on b7.  So some time soon, you want to play a move like ...Bc6 to defend that pawn.  In fact, if you play ...Bc6 right away, it's almost as good as ...Rxd1.  But the computer thinks it's even better to play 15...Rxd1+ 16. Qxd1 Bc6.
With your chosen move, white missed an opportunity.
Option 1: 15...Ne7 16.  Qxb7 doesn't work for white, because of 16...Rxd1+ 17. Nxd1 Qe1+ winning the knight.
Option 2: 15...Ne7 16. Rxd8+ Qxd8 17. Qxb7, and now white has two pawns in exchange for the bishop, and the game is almost on equal terms (black is still ahead, but it's not as good as if you'd played 15...Rxd1).
Suggestion: if you don't already know the word "zwischenzug", look it up and think about how it relates to this position. Sometimes the engine isn't really telling you about the next move, but pointing out something further along the sequence.


Fun variants in teaching chess to children

For kids younger than 6, you could try the following:

Tag/Chase

You start by a specific number of pieces(no pawns or kings) on the board mixed.

One piece is "it" and this piece "chases/attacks" the other pieces.
All the other pieces try to "run away" from this piece.
If "it" captures a piece, the latter piece is "it"

The players switch when a piece becomes "it", just remember to give a turn to player 2 when switching.

It can be more fun, as the kid has to calculate only 1 piece in relation to the others and it learns to fork and pin pieces. You could add an extra variant later and say the piece has to be undefended.

Tag/Chase without switching sides

A queen is "it" and tries to capture all other pieces, one after the other.

Chess without captures

Captures are not allowed, the goal is to learn how the pieces move.


alpha-beta algorithm returns a value between alpha and beta inclusive?

My usual reference is https://chessprogramming.wikispaces.com/Alpha-Beta#Implementation-Negamax%20Framework, which I believe is correct.

In your lecture slide, if score > beta ==> alpha = score ==> return alpha which is greater than beta. Thus, the claim looks incorrect to me.

You don't need to prove "increasing function of alpha" because any score less than alpha is a bad move for you, so you would ignore it.

Aspiration window width is a parameter and there is no definitive answer. You don't want it too big, or too small. You'll need to run tests...


Can I get by without a book for learning my opening repertoire (aside from the Sicilian Najdorf and KID)?

At the USCF 1400-1500 level, the amount of reading you are planning on doing is already far too much. When you play people at your level they'll leave book pretty early; when you play people 400 points higher they'll beat you whether or not you have 12 moves memorized. The theory simply isn't going to matter for the vast majority of your games. Save the detailed reading and memorization until you get closer to 1800 at least. For now just play what you like, and after your game look things up in a database or a nice survey book like Fundamental Chess Openings (and if you want to know the ideas behind various openings, FCO is a fine place to start). Take the time you would have spent studying openings and use it to study tactics and endgames.

Of course, if you get lots of enjoyment from reading opening manuals cover to cover, I don't want to stop you. But it's not an efficient way to improve your results (especially at your current level), and you certainly don't need to do it for every opening you think you might encounter.


It would seem to be max( |a_2-a_1|, |b_2-b_1| ). Whichever of the horizontal or vertical distances is greater, the bishop will always travel over at least that many squares and does not need to travel over any more than that many squares.
This article seems to use distance to mean "number of squares passed over while moving the piece from the source to the destination". In that sense the distance from a1 to c3 for a queen is 2 (Chebyshev distance), not 4 (Manhattan distance); it goes to b2 and then c3, not through b1, c1, and c2.


Most pieces involved in checkmate in actual game?

After going through a list of games with king hunts, I found game at last in which 6 pieces are involved in the mate!

[Title "Alexander Alekhine-NN, Simul 34b, Moedling Austria, 3/24/1936"]
[FEN ""]
[startply "33"]

1. e4 e5 2. d4 f6 3. dxe5 fxe5 4. Qh5+ Ke7 5. Qxe5+ Kf7 6. Bc4+ d5 7. Bxd5+ Kg6 8. Qg3+ Kh5 9. Bf7+ g6 10. h3 Qf6 11. Nf3 Be7 12. Qg4+ Bxg4 13. hxg4+ Kxg4 14. Nh2+ Kh4 15. Nf1+ Kg4 16. Be6+ Qxe6 17. f3#

The Bc1 prevents the Black king from moving to f4 and g5, the e4 pawn covers f5, the f3 pawn is giving mate, the Nf1 covers g3, the g2 pawn protects the mating piece and covers h3, and the Rh1 covers the h3, h4, and h5 squares.

Upon seeing this question, I remembered entry #355 of Tim Krabbe’s Chess Diary, which gives some examples of checkmates involving all four minor pieces. The best and simplest example is this game.

[Title "Vasily Borisovich Malinin-Viktor Savinov, Leningrad Russia, 1988"]
[FEN ""]
[startply "71"]

1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. bxa6 Bxa6 6. Nc3 d6 7. Nf3 g6 8. g3 Bg7 9. h4 O-O 10. h5 Nbd7 11. hxg6 hxg6 12. Bh3 Re8 13.  Qc2 Rb8 14. Be3 Nxd5 15. Qxg6 fxg6 16. Be6+ Kf8 17. Nxd5 Rxb2 18. Ng5 Nf6 19. Nf4 Qa5+ 20. Kf1 Bxe2+ 21. Kg1 Reb8 22. Bf7 Rb1+ 23. Kh2 Ng4+ 24. Kh3 Rxh1+ 25. Rxh1 Nxf2+ 26. Bxf2 Bg4+ 27. Kxg4 Rb4 28. Kf3 Qa3+ 29. Be3 Qa8+ 30. Bd5 Qa5 31. Nfe6+ Kg8 32. Nc7+ e6 33. Bxe6+ Kf8 34. Nh7+ Ke7 35. Bg5+ Bf6 36. Bxf6#

This is easily deduced to be a pure mate, thus raising the known record to four pieces.

Also, to user @John Coleman from the comments, here’s a king hunt, with four pieces, for you. :-)

[Title "Roland Schmaltz-Ronen Har-Zvi, Internet Chess Club, 3/7/2001"]
[FEN ""]
[startply "48"]

1. e4 Nc6 2. Nc3 e5 3. g3 Bc5 4. Bg2 Nf6 5. Nge2 d6 6. h3 Bb6 7. O-O O-O 8. Kh2 Re8 9. f4 exf4 10. gxf4 Ng4+ 11. Kg3 Nf2 12. Rxf2 Qh4+ 13. Kxh4 Bxf2+ 14. Ng3 Re6 15. Kg4 Nd4 16. f5 Rg6+ 17. Kf4 Rxg3 18. Qf1 g5+ 19. fxg6 Ne6+ 20. Kf5 Ng7+ 21. Kf6 Rxg6+ 22. Ke7 Re6+ 23. Kd8 Bb6 24. Nd5 Re8#


Testing an engine (UCI) against an older version of itself

Cutechess is a very good solution for this. You can use either the CLI or the GUI to run matches of engines (both UCI and XBoard protocol), and at least the CLI even supports SPRT as a termination criterion of the match, see the help.

Cutechess is also heavily used in the development of Stockfish when running matches between different versions of Stockfish on fishtest.


Polyglot opening book: getting incorrect moves

I have found the problem: my board representation was different and while my ranks are also from 0-7, but they are counted from the black side, while in the polyglot encoding, they are counted from the white side (which makes sense).
So I had to invert my ranks like so:
unsigned short fromFile = (moveKey>>6)&7,
                          fromRank = 7 - ((moveKey>>9)&7),
                          toFile = (moveKey>>0)&7,
                          toRank = 7 - ((moveKey>>3)&7);

Files remain unchanged. I am now getting reasonable output:
Finding moves for board key: 823c9b50fd114196
Move found: c7c5
Move found: e7e5
Move found: c7c6
Move found: e7e6


I'll go through the game and address your points.

In the opening, you should have played 6...Bf5 (or 6...h6 then 7...Bf5, like you said). The reason for this is that in the Exchange QGD, your light-squared bishop is bad, while White's light-squared bishop is good. If White loses his light-squared bishop, playing the thematic b5 push of the minority attack becomes difficult. Back to the point: by developing your bishop to f5, White cannot bring his bishop to d3, or else you do the favorable exchange.
7...h6 is a very subtle mistake, for a few reasons. First, in the exchange QGD White would prefer to have his bishop on f4, not g5. The reason he doesn't play 6.Bf4 immediately is that you can answer with 6...Bd6! in one go. By playing 7...h6, you give White a "second chance" to play Bf4, and now you have to waste another move to counter with ...Bd6. The second reason 7...h6 is a mistake is that you can't play ...Ng6 in the middlegame, since the knight is not supported enough on g6 and White can just played Bxg6. In the Exchange QGD, playing ...Ng6 is very important. It's far better than ...Ne6, since it blocks White's Qc2+Bd3 battery, and also attacks White's dark-squared bishop on h4 or f4.
12...Ne6 is actually fine, given your options. After 13.Bd3, you should have played 13...g6, 14...Ng7, 15...Bf5. This is an important idea that lets you exchange light-squared bishops. Remember it, if you are only able to develop your f8-knight to e6 (normally, prefer the g6-square for the knight).
14...Bf8 is normally a good idea, but because White has 15.Bh4 it's not so good here. A better plan would be playing 14...Rc8 and 15...c5. This undermines the e5-knight's support from the d4-pawn, and exploits the White queen's position on c2.
I don't think 16...Nf8 is that bad a move, given that you wanted to play ...Nh5. Playing ...Nh5 immediately would have dropped the knight due to Nxf7 Kxf7 Bg6+.
17...a6 was absolutely fine. By playing ...a6, you force White to waste at least a tempo playing a4 (since without this move he can't play b5 now, due to ...a6). Also, if White wants to play a4 then he must protect the b4-pawn, or else you'll play ...Bxb4. So ...a6 really ends up forcing White to waste about two tempi countering it.
I like 21...h5! After playing ...h4 and exchanging everything, you end up with a queen on h4. Then, you can do a Rook lift with ...Re6 + ...Rh6, building a battery on the h-file. Another idea is even playing 21...g5!? followed by ...g4, forcing White's knight to move away, and then ...h5 and ...h4. The problem is that White can play 22.Bf5, but you can still play 22...g4 with an interesting game.
I don't like 27...Bc8 because it breaks the coordination of your Rooks. After 28.bxc6 bxc6 29.Ra1, you're facing a difficult defence. Backing up two moves, I think 25...Re7 is strong, simply protecting the d7-bishop. After 26.b5 cxb5! 27.axb5 Bxb5 28.Bxb5 axb5 29.Rxb5, your e7-rook and queen protect the b7-pawn (which is passed, to boot). Note that on 27.Nxd7 Qxd7 28.axb5, you can play 28...a5! with a dangerous passed a-pawn. This trick of side-stepping White's b5-push with ...a5 is how Karpov once tricked Korchnoi in a game.
You're right, the endgame was lost. The d5-pawn was too weak to be held on to, and then White's just up two pawns. An opposite-coloured bishop ending without rooks wouldn't have helped much. Opposite-coloured bishops are only good against two extra pawns if you can set up a blockade on the colour complex of your bishops. With all White's pawns so close together, they form a veritable armada that can keep control over the dark squares.


Does depth (number of ply) still matter once it is high enough?

Yes, those 15 depths very much matter.

Consider this position that occurred in Kasparov's Immortal Game vs Topalov.

  [White "Kasparov"]
  [Black "Topalov"]
  [FEN "b2r3r/k4p1p/p2q1np1/NppP4/3R1Q2/P4PPB/1PP4P/1K2R3 b - - 0 24"]

I tested this position with several engines. Some engines, at depth 15, failed to detect that 24...cxd4 is a losing move and thought it was winning. Those same engines, at a greater depth, played the correct move 24...Kb6!

For example, even an engine as powerful as Stockfish 4 initially at depth 21 thinks the losing move 24...cxd4 is correct.

Stockfish DD 64 SSE4.2: 24...cxd4 25. Re7+ Kb6 26. Qxd4+ Kxa5 27. Qc3+ Kb6
28. Qd4+ Qc5 29. Qxf6+ Bc6 30.Qxc6+ Qxc6 31. dxc6 Rd1+ 32. Ka2 f5 33. c7 Rc8
34. Rxh7 Rxc7 35. Rh6 Rc6 36. g4 f4 37. g5 Rd2 38. c3 Rxc3 39. Rxg6+ Kc5
40. Bg4 Rcc2 41. Rxa6 Rxb2+ 42. Ka1 Rbc2 43. Kb1
(-1.45/21)

The same engine, when kept on for a little more depth, shows 24...Kb6 to the correct move.

Stockfish DD 64 SSE4.2: 24...Kb6 25. b4 Qxf4 26. Rxf4 Nxd5 27. Rxf7 cxb4
28. axb4 Rhe8 29. Rxe8 Rxe8 30. Nb3 Re1+ 31. Kb2 Re2 32. Rxh7 Nxb4
33. Kc3 Nd5+ 34. Kd3 Rxh2 35. Rh4 Ne7 36. Nd4 Nc6 37. Nxc6 Bxc6 38. f4 Kc5
39. Be6 Rxh4 40. gxh4 Bd5 41. f5 gxf5 42. Bxf5 a5
(-0.78/26)

Fritz 11 SE, at depth 15, also failed. But it found the correct move at depth 16!

Fritz 11 SE: 24... cxd4 25. Qxd4+ Qb6 26. Re7+ Nd7 27. Qe5 f6 28. Qc3 Qg1+
29. Ka2 Bxd5+ 30. Nb3 f5 31. Qc7+ Ka8 32. Rxd7 Rxd7 33. Qxd7 Bxf3 34. Qd6 Qa7
(-1.44/15)

Fritz 11 SE: 24... Kb6 25. b4 Qxf4 26. Rxf4 Nxd5 27. Rxf7 cxb4 28. axb4 Nxb4
29. Nb3 Bd5 30. Rf6+ Nc6 31. Nd4 Rdf8 32. Rd6 Kc5 33. Rxc6+ Bxc6 34. Ne6+ Kd6
35. Nxf8
(-0.59/16)

Also consider this incredible problem like position that I found here.

Stockfish was not able to find the winning line 1. Be2+! until depth 31 and up until then it thought it was a bad move. I demonstrate the win here. The point is that Black is in zugswang because of mate threats and has to either give up the queen or move the a pawn which would allow White to create a passed pawn and win.

   [FEN "8/2p1q3/p3P3/2P4p/1PBP2kP/2N3P1/7K/8 w - - 0 1"]

   1. Be2+ $1 Kf5 2. Nd5 $1 Qxe6 3. Bd3+ Kg4 4. Be4 $3 Qh6 (4... Qxe4 5. Nf6+)
   5. Nf4 Qg7 6. Nd3 $1 Qxd4 7. c6 $1 a5 (7... Qxe4 8. Nf2+ Kf3 9. Nxe4 Kxe4
   10. Kg2 Kd4 11. g4 hxg4 12. h5 Ke5 13. h6 Kf6 14. Kg3 Kg6 15. Kxg4 Kxh6
   16. Kf5 Kg7 17. Ke6 Kf8 18. Kd7 Kf7 19. Kxc7) 8. b5 $1 a4 9. b6 cxb6
   10. c7 Qxe4 (10... Qc3 11. Nf2#) 11. Nf2+ Kf3 12. Nxe4 1-0

Here's the engine log from Stockfish 4. As you can see, it detects that 1. Be2+ is winning, only on depth 31!

Stockfish DD 64 SSE4.2: 1. Be2+ Kf5 2.Bc4 c6 3. Ne2 Qf6 4. Kg2 Kg4 5. Nf4 Qxd4
6. Bd3 Qe3 7. Be2+ Kf5 8. Bf3 Qd2+ 9. Kh3 Qxb4 10. e7 Qe1 11. Ne2 Qf1+ 12. Kh2 Qf2+
13. Kh3 Qe3 (-1.05/22)

Stockfish DD 64 SSE4.2: 1. Be2+ Kf5 2. Bc4 Qf6 3. Ne2 c6 4. Bxa6 Qxe6 5. Bd3+ Kf6
6. Nf4 Qe1 7. d5 Qxb4 8. dxc6 Qxc5 9. Be4 Ke7 10. c7 Kd7 11. Nd5 Kd6 12. Kh3 Qc4
13. Bg2 Qg4+ 14. Kh2 Qc8 15. Be4 (-1.15/26)

Stockfish DD 64 SSE4.2: 1. Be2+ Kf5 2. Bc4 Qf6 3. Ne2 c6 4. d5 cxd5 5. Bxd5 Qb2
6. Bc4 Kf6 (-1.01/28)

Stockfish DD 64 SSE4.2:  1. Be2+ Kf5 2. Nd5 Qxe6 3. Bd3+ Kg4 4. Be4 Qh6 5. Nf4 Qf6
6. Nd3 Qxd4 7. c6 Qxe4 8. Nf2+ Kf3 9. Nxe4 Kxe4 10. Kg2 Ke5 11. Kf3 Kf5 12. g4+ Kf6
13. gxh5 Kg7 14. Kf4 Kf6 15. h6 Kg6 16. h5+ Kh7 17. Kg5 Kg8 18. h7+ Kxh7 19. Kf5 Kg7
20. Ke6 Kh6 21. Kd7 Kxh5 22. Kxc7 Kg5 23. Kd7 (6.06/31)


Open source chess playing or pgn viewing libraries

Crafty

Crafty is a strong chess programm and can be used with Winboard, Xboard and Scid. So it is available for all major operating systems.

Scid

Scid can maintain databases of chess games, you can analyse (end) games.The software is available for all major operating systems.

Xboard

Xboard is a user interface to the Internet Chess Server. It uses the X Windows System, so I assume this runs only under GNU/Linux. Xboard can be used as a viewer and supports all forms of chess.


Yes, it does look like Reinfeld made a mistake, but white should still be doing well after 18... Qf6.

White should now play 19. Qc1! hitting the queen and the bishop.  Now black's best continuation is to sacrifice the queen with 19... Bxf3 20. Bxf6 Bxd1

[FEN "r4rk1/b4ppp/p1b1pq2/1p6/1P6/P1Q1PN2/BB3PPP/3R2K1 w - - 1 18"]

1. Qc1 Bxf3 2. Bxf6 Bxd1

One possible line from here is

[FEN "r4rk1/b4ppp/p3pB2/1p6/1P6/P3P3/B4PPP/2Qb2K1 w - - 1 18"]

1. Bxg7 Kxg7 2. Qxd1 Rad8 3. Qg4+ Kh8

and white has a queen and a pawn for the two rooks, but a strong attack because black's king is so weak.

To summarize, it does appear that Reinfeld made a mistake because after 16... Nc6? white can simply play 17. Qc3! and win easily, but even the line he gives should be okay for white.


Which countries are easiest to gain rating points and earn FIDE titles in?

Rating is a lagging indicator. That is, it gives an estimate of playing strength in the past. Therefore by definition players who are improving are underrated and players who are declining in strength are overrated.

Therefore as a first step if you can enter late you should look at the age profile of the entries and avoid entering tournaments with lots of very young players (who are likely to be still improving) and try and enter tournaments with old (preferably senile :-)) players (who will likely be on the decline).

Looking at the raw FIDE rating data which FIDE supply from January 2019 (I haven't yet loaded the latest February data in my database) and running a query gives the following results for average Date of Birth year for active players in federations with at least 1000 active players -

P 1. Denmark - 1966.4
 2. Netherlands - 1969.5
 3. Switzerland - 1970.95
 4. Finland - 1972.8
 5. Austria - 1974.2
 6. Germany - 1974.6
 7. Serbia - 1974.8
 8. Sweden - 1976.1
 9. Ireland - 1976.2
 10. Bosnia Herzegovina - 1976.7
 ...
P 22. Spain - 1984.9
P 23. Australia - 1985.2
 ...
P 34. France - 1986.9
 ...
P 56. Iran - 1992.6
 ...
P 70. India - 1997
P 71. Turkey - 1997.8
 ...
P 76. China - 1999.2

So, for best results try and enter tournaments in countries at the top of the list and avoid countries at the bottom.

Note that Spain and France are not much different to Australia and Turkey is on a par with India - far too young!


Engines like Stockfish and Komodo are not able to work out the previous moves, because that is not what they are programmed for.

However, it is vanishingly unlikely that anybody can ever program an engine that works out legal previous moves. The logic of working out whether a possible previous move is legal or not is extremely difficult.

To start with, how do we list possible previous moves?

Possible previous moves, called retractions (if we ignore legality for a second) are easily found algorithmically - every piece retracts as it moves in forward chess (except pawns), and they could also "uncapture" an enemy unit - pawn, knight, bishop, rook or queen. e.g. wBc4 takes pawn on f7 in reverse looks like the bishop moving from f7 to c4, with a black pawn appearing on f7.

Pawns move 1 square backwards, and uncapture one square diagonally backwards. (You can figure out what the double step looks like.)

With regard to checks, one can retract into what looks like "check" in regular chess, and one must always retract to never leave the opponent in "check". (So if the previous example of wBc4xbPf7 checks the black king on e8, it required white to retract the bishop to remove the "check".)

Uncastling is easy to visualise (and adds the constraint that the king or rook cannot retract again). Un-en-passant is hard to describe and forms the basis of many classic retro problems. Unpromotion is again easy to visualise.

So listing all potential retractions is not difficult, from a programming standpoint. The incredibly difficult part is determining which retractions are legal. There are many reasons why a retraction cannot be legal, ranging from simple (retracting an uncapture to leave 9 black pawns on the board, for instance) to highly convoluted (cf. most retrograde analysis problems, see the Retro corner.)

See for instance this problem by Troitsky on Chess.SE, and my accompanying answer to it. A lot of logic goes into proving that there is in fact only one legal retraction by black, and this is not obvious, involving counting pawn captures, considering their order, and tempo constraints.

To write an engine to perform such a task, one must be able to elucidate the human logic behind it in such a way that a computer can execute the logic. This simply does not seem possible at all, given that "legality of retractions" is far more nebulous than "legality of forward chess moves".


Stockfish: different nodes numbers with identical calls

It's likely due to Stockfish's transposition table (essentially a fast lookup table that Stockfish can use to refer back to positions it evaluated before). During your first run, information about visited positions was stored in the table. Then on the second run, Stockfish may have looked at some of Black's moves after depth 1 (since it's already evaluated all states at depth 1).

SmallChess' answer to this question may be useful if it's still confusing:

How to read score from stockfish - inconsistent response every call?

Edit: to test if it is the transposition table behind this, try to reset it after the first run (close the whole program if you can't figure out how). Then on the second run, the number of nodes should be the same (as well as the centipawn evaluation).


In a KP-K endgame, if the enemy king is in front of the pawn, is it always a draw?

If the king is on the sixth and the pawn is on the fifth (and it's not a rook pawn), then it's a win for the side with the pawn, no matter who has the move:

[FEN "4k3/8/4K3/4P3/8/8/8/8 w - - 0 1"]

1. Kd6 Kd8 2. e6 Ke8 3. e7 Kf7 4. Kd7 Kf6 5. e8=Q *

With Black to move:

[FEN "4k3/8/4K3/4P3/8/8/8/8 b - - 0 1"]

1... Kd8 2. Kf7 Kd7 3. e6+ Kd8 4. e7+ Kd7 5. e8=Q+ *

If you back it up, though, the position is a win with Black to move and a draw with White to move. If White has to move first, Black can simply mirror the movements of the White king until White moves the pawn forward.

[FEN "8/3k4/8/3K4/3P4/8/8/8 w - - 0 1"]

If the pawn is in front of the king, the general strategy is to make sure to oppose the enemy king when it goes alongside its pawn, to prevent it from getting in front.

[FEN "4k3/8/4P3/4K3/8/8/8/8 w - - 0 1"]

1. Kd6 Kd8 2. Ke5 Ke7 3. Kf5 Ke8 (3... Kf8?? {This loses! If you take this critical square too soon, before the enemy king is alongside the pawn, you can't stay on the square when the enemy king does advance.} 4. Kf6 Ke8 5. e7 Kd7 6. Kf7) 4. Kf6 Kf8 5. e7+ Ke8 6. Ke6 {Stalemate.} 1/2-1/2


You can select your starting rating on the register page by changing the skill level options.

For example, if you select "expert" your starting ratings will be 1800 (at least when I tried it).

So, to answer your question, "How is it decided what is the initial value of the elo rating of a new member?", it is decided by what option the user chooses.


Chess challenge #9: Can you solve it in less than 5 minutes?

Got it barely under the mark.  Not sure if it helped or hurt that I knew the mate-in-2 with a similar position (move the Ke4 to f5).

   1 Qb2!! Kd7 2 Qe5! Kc8/Kc6 3 Qc7/Qd5#!

Spoiler for mate in 2 (Kf5 Qb5 Ba5 / Kc8):

   1 Qb3! Kd7 2 Qe6#!


Fritz for Fun 13: how do I add positions to a new database?

I'm not familiar with Fritz for Fun 13, but I have information about Fritz 13, which I will assume is the basis for your variant.

I'll also assume that you want to add a game / position manually, rather than import one (or a collection) from, say, a PGN file.

New Game: You can enter the moves for a new game by simply setting the players to 2-player mode, instead of player vs Fritz.  If you can't figure out how to do that, turn on "Infinite Analysis" mode with Alt-F2. That will prevent Fritz from entering an engine move. Then, just enter the moves.

New Position: Choose the menu option "Insert, Position Setup". Then, clear the board (in Fritz 13, it is pre-populated with the start position), and drag-and-drop or click-click your way to populating the position. Hint: In Fritz 13, if you click the white piece in the legend, and then left click on a square, you get a white piece. If you right-click on a square, you get a black piece. So, you can save yourself about 30-40% of your setup clicks by just selecting white pieces.

Finally, specify the side to move, using the appropriate checkbox. If one of the kings is in check, of course, you cannot save the position until that side is specified as having the move.

You may have to specify castling rights (kingside and/or queenside) for either white or black or both, if the kings and rooks are in their original positions, but the setup wizard (dis-)allows that side's castling erroneously. However, the wizard settings are generally correct, in my experience.  Only when either the king or the rook have moved from their home squares and then returned to them will the wizard's settings be wrong.  Don't worry about the king being in check or any of the relevant castling squares being under attack; the move entry function will prevent an immediate castling attempt in that situation.

Then, confirm that you're done with the position setup using the Ok button. You will then have an open game window (but not a saved game).

Saving Games and Positions: The last step is simply to save the game/position. In Fritz 13, if you had clicked on a database (or had a list open) before you started the game/position entry process, that database would be where the game/position is saved by default if you use the "Save" menu item.  Otherwise, you have to navigate to the appropriate database using the "Save As..." menu option. So, I generally select my database first.

Tip: You can actually use a copy/paste operation to save the game from an open game window into a database. There are tons of ways to specify "copy", including right-clicking in the Notation pane, or by typing [Ctrl][C]. Once you've put the game in the clipboard (the results of this copy action are invisible, but trust me, it's there), you can paste it (any way you like) into a selected or open database, a Notepad window or other text editor, or an email as a text attachment.  But watch out; if you paste it into a database window, different versions of Fritz are inconsistent about whether a subsequent Replace operation will affect the pasted game.  To be safe, I close the open game window, and then open the game from the database list.  That ensures that a later Replace will put the game back in that slot.


Resource with chess problems in electronic format with solutions

If you are looking for tactical puzzles, there is always CT-Art from Convecta. You can also try Tactic Trainer for Android. It has a nifty difficulty rating system.

Also there is an online resource I forgot to add : http://www.yacpdb.org/


Potential exchange sacrifice in a King's Indian Defence middlegame

First, it is highly unlikely that you will get a definitive answer here since computers are not great in these types of positions where the danger to white might be 10 moves down the road. It is also not uncommon for black to "lose" a rook in this opening, the Classical King's Indian, however, we often find that black's k-side attack is simply too strong in practice.

Computers are not yet strong enough to see this deeply, and even if they could, you are playing a human being. As a practical matter, positions like these, which are so complicated and dangerous, even if technically not correct, they are fine to play in practice...ask Tal. :) Still, you also missed some quicker wins too.

In the line 21.fg Ne4, you clearly have compensation since the eval is only +.7, and falls to about +.4 the move after taking on a8 and the recapture, however, the question is if you can ignore the immediate recapture, and just play something else. I do not think so since white's q-side attack comes too quickly. I think you have to take back immediately, and then bring the queen back to the k-side. If you have to do that, you are right that it is probably wrong.

All of this is a bit moot since the most popular move is 18...h5, which scores at only 33% for white compared to 83% after 18...Bf8. I like the idea of the pawn roller there since it is more flexible when you play g4.

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

    1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. O-O Nc6 8. d5 Ne7 9. Ne1 Nd7 10. Be3 f5 11. f3 f4 12. Bf2 g5 13. b4 Nf6 14. c5 Ng6 15. cxd6 cxd6 16. Rc1 Rf7 17. Nb5 (17. a4 {a4 is a more common move here.}) 17... a6 18. Nc3 Bf8 (18... h5 {h5 is a more common move here.}) 19. Na4 Bd7 20. Nb6 g4 21. Nxa8 (21.fxg4 Nxe4 22.Nxa8) 21... g3 22. hxg3 fxg3 23. Bxg3 Nh5 24. Bf2 Ngf4 25. Nb6 Rg7 26.Nxd7 Qxd7 (26... Rxg2+ 27. Nxg2 Qg5-+) 27. Kh2 Nxg2 (27... Rxg2+ 28. Nxg2 Qh3+ 29. Kg1 Qxg2#) 28. Nxg2 Rxg2+ 29. Kxg2 Nf4+ 30. Kg1 Qh3 0-1


The second part of the question is more straightforward, so I'll look at that first.

  Is castling with a "ghost" rook like this legal where there was a rook
  on a1 at the start of the game but it was captured before it could
  move?

Article 3.8.2 of the FIDE Laws of Chess describes how castling works:

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

This explicitly states that castling involves two pieces, the king and the rook, and it describes how the rook moves in this manoeuvre. If you don't have an unmoved rook on the board then you can't castle. Therefore castling with a "ghost" rook is illegal.

With this clear the first part becomes easier to answer.

  Is castling with a "ghost" rook like this legal where there has never
  been a rook on a1 because it was given as odds at the start of the
  game?

It depends on the rules of the competition or individual game, if the game is a one-off. If the rules state that apart from the initial position of the board the FIDE Laws of Chess apply then clearly it is illegal.

In the absence of such a clarification the best guide is probably the chess historian Edward Winter. In his chess notes for March 2009, note 6029 he considers exactly this question:

  6029. Castling with a phantom rook From Mark Thornton (Cambridge, England):

  ‘In rook-odds games could the odds-giver castle with the “phantom
  rook”? For example, if White gave the odds of his queen’s rook, could
  he play Ke1-c1? And, if so, were the castling rules the same as if the
  rook were present?’

According to Winter there is no conclusive ruling one way or the other. He quotes probably the most sensible approach from Howard Staunton on page 35 of Chess Praxis (London, 1860):

  When a player gives the odds of his king’s or queen’s rook, he must
  not castle (or, more properly speaking, leap his king) on the side
  from whence he takes off the rook, unless before commencing the game
  or match he stipulates to have the privilege of so doing.

There are strong feelings on both sides of the argument. Here is more from Winter:

  However, in a review of the book on pages 88-89 of the March 1890 BCM
  Edward Freeborough disagreed. After stating, with respect to level
  games, that castling should be described as a move of the king and
  that the king should therefore be moved first, Freeborough observed:

  ‘It follows logically that the fact of giving the odds of a rook
  ought not to deprive the king of his privilege of taking two steps to
  the right or left as his first move.’

  Page 36 of The British Chess Code (London, 1903) stated:

  ‘In the absence of agreement to a different effect, a player may
  castle (by moving his king as in ordinary castling) on a side from
  which, before the commencement of the game, the player’s rook has been
  removed, provided that this rook’s square is unoccupied and has been
  unoccupied throughout the game, and that the same conditions as to
  squares and as to the king are fulfilled which are required for
  ordinary castling on this side.’

  The above text was quoted on page 275 of the June 1916 Chess Amateur
  when a revised edition of the Code was envisaged. Comments were
  invited, and on page 305 of the July 1916 issue ‘Simplex’ wrote:

  ‘This I think sheer nonsense. If a player gave me a rook and wanted
  to castle on this rook’s side, I should say, “No, you don’t, you can’t
  castle without a castle”. Let’s have no pretence. If a player gives a
  rook, let him give it totally not half. Receivers of odds are not
  strong players, and to see the nominal giver of odds move his king a
  couple of squares would be disconcerting. No; if a player gives odds
  let him give them without pretence.’

  A contrary view was expressed by W.S. Branch on pages 333-334 of the
  August 1916 Chess Amateur:

  ‘Re Chess Laws, page 305 (July), and as to “castling without rook”, I
  would say, first, that you can’t “castle the king” – the full and
  proper term, of which “castles” is an abridgment – without a castle.
  The phrase should be “moving the king as in castling”. I believe that
  the right of the odds-giver to move his king, once in a game, as in
  castling, has always been upheld since “castling” was invented
  (sixteenth century). It existed, as part of the “king’s leap”, long
  before “castling” was invented, and long before the rook was ever
  called a “castle”. The giving of the rook as odds should not deprive
  the king of any of his rights.’

  Branch then gave further historical details regarding the king’s leap.
  By 1916, however, the practice of giving odds was disappearing,
  without any formal resolution of the ‘phantom rook’ question.

Winter revisits this topic in note 6035. "Castling with a phantom rook (C.N. 6029)" with some interesting anecdotes regarding castling with a ghost or phantom rook.


Where can I find a rarity table of chess player ratings?

According to the list downloaded here, there are currently 261782 players with a FIDE rating. I wrote a small program to analyze it, and here are the results:

-------------------------
Rating  Number of players
2800+   5
2750+   18
2700+   43
2650+   114
2600+   262
2550+   514
2500+   921
2450+   1641
2400+   3130
2350+   5223
2300+   8669
2250+   13791
2200+   21033
2150+   30045
2100+   41411
2050+   54631
2000+   69229
1950+   83243
1900+   97932
1850+   112783
1800+   127483
1750+   141826
1700+   155776
1650+   168856
1600+   180987
1550+   192154
1500+   202332

Keep in mind that there are a lot of countries where club level players (1500 - 2000) have a national rating but not a FIDE rating.

For reference, here is the Java program I wrote. Feel free to modify it for your own analysis.

public static void main(String[] args) throws Exception {
    BufferedReader reader = new BufferedReader(new FileReader("rating.txt"));
    String line;
    int[] frequencies = new int[3000];
    boolean first = true;
    while ((line = reader.readLine()) != null) {
        if (first) {
            first = false;
            continue;
        }

        frequencies[Integer.valueOf(line.substring(113, 117))]++;
    }

    int total = 0;
    for (int rating = 3000 - 1; rating >= 0; rating--) {
        total += frequencies[rating];
        if (rating % 50 == 0) {
            System.out.println(rating + "+\t" + total);
        }
    }
}


Computer evaluations: How trustworthy are they?

Different engines have different "scales" for their numerical evaluations. For instance, in a typical middlegame position with plenty of play left, when Houdini says +2.00 or better, it is highly probable that White has a winning advantage (though even here I've included qualifications for a reason). But consider: one could modify the source code of Houdini and double the absolute values of all numbers involved in evaluations; one gets an engine of identical strength that produces identical play, but now +4.00 means what +2.00 used to mean. This illustrates that one shouldn't expect a uniform numerical threshold across engines that typically indicates a winning advantage.

More than this, though, it's important to understand that a numerical engine evaluation of a position (as opposed to an outright declaration of inevitable mate) never strictly translates to "a won game," even for a single, fixed engine. A key point is that numerical evaluations have no clear-cut "meaning" in broad chess terms, and are rather just a substitute for sentient thought that is used to mechanically guide an engine toward generally desirable outcomes by influencing which move it selects at each point in the game; in this light, what is ultimately most important to an engine's play is just the difference in evaluation assigned to potential moves, rather than anything about the absolute values involved. The numbers are useful to the engine itself, which needs something that concrete in order to make a decision for one move over another, but we humans shouldn't be too quick to read more meaning into the magnitudes involved with thoughts like "+X means a win."

In particular, the further and further we get toward an endgame as opposed to a middlegame, the less we can use a rule of thumb (like my +2.00 for Houdini in middlegames above) about a certain threshold being enough for a win. One key reason for this is the difficulty that engines have recognizing fortresses, where an abundance of extra material still isn't enough to win. For instance, when I feed Stockfish this position,

[FEN "5k2/6p1/5r2/3Q3P/4K3/8/8/8 w - - 0 1"]

after a couple minutes thought it is giving an evaluation of about +7.00, and in a typical position, when Stockfish says that, you almost certainly do have a win on your hands. Nevertheless, this is a dead draw, and a human can see this easily once the fact is realized that Black can just shuffle the rook between f6 and h6, and so (1) the h-pawn is useless, and (2) the white king will never be able to help the white queen attack. Eventually, Stockfish will recognize a draw here too, once it butts up against 50 moves, say, or finally runs out of different moves to try and finally can't avoid a repetition, but those events are way down the search depth line.

The endgame position from your earlier question that you linked to is akin to this sort of fortress, in that the extra connected passed pawns White has there are nice and all, but ultimately not quite enough to win in that position. If an engine were to calculate for enough time to see as much information as is contained in tablebases, then its evaluation would come down to 0, but in the meantime, its evaluation algorithm has nothing better to go on than to give a + for that extra material (that it doesn't yet know is meaningless).


Attack or defend? Which is best approach to win?

A lot depends on your opponent. Finding the right moves in defence is generally much easier than finding the right moves in attack.

If you are playing a much stronger player your best chance will be if he attacks you and you can survive the attack. If he doesn't attack then part of the reason will be that he doesn't think he has built up the kind of position that warrants him launching an attack. If you try and attack in that situation then you will likely get beaten quickly. So, the best advice is to try and play openings and positions you are familiar with and concentrate on prophylaxis. Strengthen and reinforce your position. Make sure you don't have any weaknesses and always be alert to your opponents threats and the areas of the board he is building up in. Don't waste too much time looking for chances to attack him.

Conversely when you are playing a much weaker opponent your best chance will be to launch a sound attack. If both of you just try and defend there is a much greater chance of the game petering out in a long draw. But the emphasis really is on sound. Use your superior positional knowledge and experience to build up a better position with your pieces working together in the area of the board you want to launch your attack from. Don't launch it prematurely or your opponent may be able to defend correctly and successfully and either get the draw or even win on the counterattack!

If you and your opponent are evenly matched again strengthen your position first and build up before any attack. Be on the lookout for chances to attack more than you would against a much stronger player but make sure you do so from a position of strength.

In all 3 cases it is clear that early in the game you should be developing your pieces to good squares and strengthening your position. Sometimes these good squares will be in attacking positions because it makes developing other pieces easier for you and more difficult for your opponent. For example, pinning knights in openings like the Ruy Lopez. But the emphasis should be on building a sound position first and not trying to make a string of attacking moves before your position warrants it.


When you shut off the engine and turn it back on, its transposition table has been cleared. In order to continue using the saved positions, a database of some sort would be needed. This would keep getting bigger and bigger the more you used the engine though, and could become very inefficient for the engine to actually use to the sheer size.
If by a new game you mean going back to the starting position and playing out new moves (all while keeping the engine on), then it probably depends on the engine. Some engines might clear out their transposition table in order to free up space, since the old saved positions happen after a different series of moves. Engines can't keep using more and more RAM, so they have to manage their TTs effectively and get rid of positions that likely won't be useful soon/ever while the engine remains running.


Chess Engine: Generate a Bitboard of Pinned Pieces

This task is nontrivial and cannot be obtained easily or setwise from the available bitboards.

The following solution is an example for how such a task might be done for a generic slider - only obvious substitutions are necessary to convert this code to be usable for bishops, rooks and queens.

First, identify the set of possible pinning pieces by calculating sliding attacks from the king square, using the opposite side as the set of occupied squares.

BitBoard bb_pinners = slider_moves(king_square, bb_other_side) & bb_other_side;

All bitboard engines should have some function similar to bishop_moves or rook_moves, which uses magic bitboards, PEXT or Koch-Stone to generate sliding moves from a square, given a bitboard of occupied squares as blockers to the slider.

To determine the set of pinned pieces from the set of pinners, it is necessary to iterate through the set of possible pinners (this is why pinned pieces cannot be calculated setwise).

For each pinner, we consider the set of bits between the pinner square and the king square (using the utility function between), determine if there is only one bit set, and if so, add that bit to the set of pinned pieces.

BitBoard bb_pinned = 0;
while(bb_pinners) {
    Square sq = pop_bit(bb_pinners);
    BitBoard bb_possible_pinned = between(sq, king_square) & bb_own_side;
    if(only_one_bit(bb_possible_pinned)) {
        bb_pinned |= bb_possible_pinned;
    }
}

Here, pop_bit finds the index of and removes the least significant bit of bb_pinners.

Stockfish implements a similar strategy in slider_blockers to determine possibly pinned pieces.

It is also worth mentioning that even with a set of these blockers, this does not mean that they may be excluded from legal move generation because if the pinned piece is a slider itself of the correct type, it may still have legal moves despite being pinned, under the above algorithm's definition.


Pushing for Advantage with White in Correspondence chess

There is no doubt that this position is currently equal, and should end in a draw, but white has two pluses that are might make it worth playing on, at least for a while.

First, there e5 square, and the Nf3 can outpost there and possibly create some discomfort for black. Black does not have a similarly strong square for the Nf6. Note that if black ever kicks the Ne5, then e6 is weak, and if it then moves forward, then the a2-g8 diagonal is weakened....little concessions is what white wants to add up into a big concession.

Second, white has the possibility of creating a passed pawn on the queenside here. In the Capablanca days, they thought that having that extra queenside pawn was a huge advantage, but over the years, it has become more clear that it can be dealt with.

The reality is that the rooks should come off, and should white then try to mobilize the queenside majority, black will probably throw the h-pawn forward, and use the queen, h-pawn, and knight to try to create enough threats to draw.

In the end though, and I know that in correspondence with computers, it is less likely, but people do make mistakes.


Help with the Sicilian Defence - I need to understand those early pawn moves

Yes, in the Sicilian black often falls behind in development, and that is a problem -- white often gets the chance to mount an attack.

But black has some compensation. After ...cxd4 Nxd4 he has two central pawns while white only has the e-pawn. In order to attack quickly, white often castles queenside and black can use the half-open c-file to start a counter attack. His a- and b-pawns can be used in a minority attack against white's queenside. He has no clear weaknesses.

It turns out, after a century and a half of trying to refute it, that that is enough to hold the balance. Indeed, the whole situation is also risky for white and that means it can give black more winning chances than normal (as well as losing chances).

But that was by no means obvious!

It's not an easy defence to understand, and it's debatable whether weaker players should play it.


Is Colle-Zukertort a good way to improve beginner play?

The Colle is definitely not an aggressive opening in the classical sense.  If you like the positions that you get with the Colle, by all means, play it to your heart's content.

The Colle is a very conservative opening because white plays d4 and then really doesn't make any other moves to occupy the center.  Playing for theoretical equality as white might be okay if you just want to get a familiar position, but there are other openings that promise white a greater advantage, which is why top level games rarely, if ever, feature the Colle.

System openings like the Colle don't really teach you how to play chess, they teach you how to play the Colle.  The reason that the Colle is recommended to beginners is that the ideas and plans are simple, and it works fairly well against any kind of play by black.  White does frequently get an attack on black's kingside, which can be decisive if black does not defend accurately.

The biggest downside to the Colle is this: other openings, like e4 e5, will teach you concepts and themes that will apply to all parts of chess.  For instance, how to maneuver your knights and bishops in order to improve the position.  In the Sicilian (as either color), you can learn how to attack and defend - always useful.  The Colle is really limited to learning how to free the dark square bishop and how to stir up an attack on h7.  If black is on top of things, the attack will never come to fruition, and black will get a good game after striking with c5.

So my personal opinion if you want to win lots of games: learn the Colle, study all the possible positions, and memorize the moves.  If you want to improve your chess, which will lead to more wins down the road, then play main line openings and only play the Colle occasionally for a change of pace.

Some common "system" openings:

Colle (d4, e3, c3, Bd3)
Colle-Zukertort (white plays the Colle with b3 and Bb2 instead of c3)
Stonewall Attack (d4, e3, f4, Bd3)
King's Indian Attack (e4, d3, g3, Bg2, Nf3)

Notice that these openings don't try to occupy the center.  By not occupying the center, white avoids confrontation until later in the game.  This means that white can develop in a known fashion before initiating contact and only then follow the prescribed plans.


There are three checks in this position?

Kd1 Bxe2+ looks like it is another depth 2 check


GM Smerdon has written a blogpost about this.

Some of the commands:

@fbchess play  (or @fbchess play white)
@fbchess help  (will give you a list of commands)

Case sensitive algebraic notation:

@fbchess Bg7
@fbchess e4

@fbchess undo
@fbchess resign


Latest time to castle in a tournament game

This web page claims that "[the] latest castling was performed on move 48 in two games: Neshewat – Garrison, Detroit 1994 and Somogyi – Black, New York 2002."
According to https://www.chessgames.com, the first was Michigan Class A (1994), Detroit, MI USA, rd 2, Jan-15. That site gives that second game here with no tournament or match citation. These are actually both on Tim Krabbe's record page under the title "Latest castling" in the "Moves" section.
Game 1: Kingside Castling
[Title "Neshewat-Garrison, Detroit, 1994"]
[FEN ""]

1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 Qa5+ 5. Bd2 Qb6 6. Nb3 Ne4 7. e3 Qf6 8. Qf3 Qxf3 9. gxf3 Nxd2 10. N1xd2 Nc6 11. a3 d6 12. Be2 g6 13. Rb1 a5 14. O-O a4 15. Nc1 Bf5 16. e4 Be6 17. Rd1 Bh6 18. Kg2 Nd4 19. Bd3 Ra5 20. Nf1 Rg5+ 21. Ng3 Nxf3 22. b4 Bg7 23. Be2 Nh4+ 24. Kh1 Bh3 25. f4 Bg2+ 26. Kg1 Bxe4 27. Nd3 Bd4+ 28. Kf1 Rxg3 29. hxg3 Nf5 30. Rdc1 Nxg3+ 31. Ke1 Be3 32. Rd1 Nf5 33. Rb2 Bd4 34. Ra2 Ne3 35. Rc1 Ng2+ 36. Kf1 Be3 37. Rc3 Bd4 38. Rc1 Be3 39. Rb1 Nxf4 40. Rd1  Ne6 41. Nf2 Bf5 42. Bd3 Nd4 43. Bxf5 Nxf5 44. Ke2 Bh6 45. Ne4 Bg7 46. c5 dxc5 47. Nxc5 Nd4+ 48. Kf2 O-O 49. Nxa4 e5 50. Nc5 Nb5 51. Rd7 b6 52. Rb7 Nc3 53. Rc2 e4 54. Rxb6 e3+ 55. Ke1 Rd8 56. Rc1 h5

Game 2: Queenside Castling
[Title "Somogyi-Black E., New York, 2002 "]
[FEN ""]

1. e4 g6 2. d4 Bg7 3. Nc3 b6 4. Nf3 Bb7 5. Bf4 Nf6 6. Bc4 Nc6 7. O-O Nxe4 8. Nxe4 d5 9. Bd3 dxe4 10. Bxe4 e6 11. c3 Qe7 12. Ne5 Bxe5 13. dxe5 Na5 14. Bd3 a6 15. Qg4 h5 16. Qg3 h4 17. Qe3 Qd7 18. f3 Nc6 19. Rad1 Ne7 20. Bg5 h3 21. g4 Nd5 22. Qf2 c5 23. a3 Qc7 24. c4 Ne7 25. Qg3 Nc6 26. Bf6 Rh7 27. Rf2 Nd4 28. Bf1 b5 29. b4 bxc4 30. Bxc4 Qc6 31. Rd3 a5 32. b5 Qd7 33. a4 Bd5 34. Rc3 Bxc4 35. Rxc4 Qd5 36. Rc1 Nb3 37. Re1 c4 38. f4 Nc5 39. Qa3 Qd4 40. Qf3 Qd5 41. Qxd5 exd5 42. Rd1 Ne4 43. Rc2 Nxf6 44. exf6 Rh4 45. g5 Rg4+ 46. Kh1 Rxf4 47. Re2+ Re4 48. Rde1 O-O-O 49. Rxe4 dxe4 50. Kg1 Kb7 51. Rc1 Rd2 52. Rxc4 e3 53. Rc1 Rg2+ 54. Kh1 Rg4 55. Re1 Rxa4


I wrote a simple PHP script which parses ELO codes and the corresponding number of moves from chess games in PGN files. This script will output the ELO code and number of moves into a CSV file. The averages can then easily be evaluated in Excel for example.

I ran my script on a PGN file with about 6000 games which I downloaded from The Week in Chess. You can view the result here:

Full size

If you want to evaluate millions of games, to get better averages, I suggest you use Pig script or some other scripting languages which can easily handle big chunks of data.


Best resources to learn the Chigorin variation of the Ruy Lopez for both colors?

I'm not going to say its the best for exhaustiveness but great entertainment st louis chess club


When and where is the next world championship?

It will take place in 2020 at the end of the year. The exact date and location have not been revealed nor decided yet.

  When is the Candidates?

In 2020, the same year as the world championship match. It usually takes place in March, but no official information about it has been released yet.

  Where can I find the important chess tournaments online?

If you are asking about the dates, then there are many sources. The one I use is 2700chess. Scroll down to the "Future Events" section. It lists many scheduled upcoming tournaments as well as the most notable players taking part in each. There is also the Chess.com tournaments calendar.

If you are asking about the broadcasts of the tournaments, then either Chess24 or Chess.com is the right place for you. Personally I use Chess24.


Possible to simulate specific chess situations?

You could use Fritz (or any other engine under the ChessBase GUI) to do this, using the "Infinite Analysis" function, so it's definitely possible, though I have no experience with other chess software and therefore don't know how to do this with other GUIs.

As for simulations, it is possible to have the engine play many games against itself, available in the ChessBase GUI again, called Monte Carlo analysis.


Where can I download (or buy) a database of Chess960 games?

Interesting question, and the answer is little bit funny.

Guess where I found these games, would you?

On chessgames.com! But it's not called Chess960, nor Fischer's chess, nor random chess, it's called: Chess variants (000)

If you go to to ChessBase Database and you enter in the search form chess960 you will find many games.

EDIT

I emailed 365Chess.com and Chesstempo.com and they said they don't have Chess960 games, I emailed Chessgames.com and they replied.

  There are a couple of them.  There’s no easy way to pull them up, but
  here is a collection with 3.

  There might be one or two more.

I guess I did a better job than Chessgames team at finding chess960 games in their own database :)

I emailed Chess.com, they said

  Thanks for your email. Unfortunately we don't have a database of
  Chess960 games available for download. Premium members of Chess.com
  have access to all the Chess960 games played on Chess.com.


What was the time control in tata steel tournament?

http://www.tatasteelchess.com/tournament/information

Time control

The time control is: 100 minutes for 40 moves, followed by 50 minutes for 20 moves, then 15 minutes for the remaining moves with 30 seconds cumulative increment for each move starting from the first move.

So you remembered correctly.

And, yes, should be the same for A and B.


If you spent roughly an hour a day for 6 months, then it's absolutely reasonable at your playing strength. The only chess-related thing you have to do is just practice playing blindfolded. Gradually it'll become more natural.

You could also do exercises for improving your overall memory (so not just related to chess). Such exercises are outside the scope of this community, but I'm sure you can find many online.


How to disambiguate checking moves in descriptive notation?

My understanding is that it's OK to use "ch" to disambiguate a move, but it's not OK to use the absence of "ch" to disambiguate. For example, in your first diagram, Ndb5 could be written as N-N5ch, but Ncb5 could not be written as simply N-N5.

I don't have a source stating that explicitly as a rule, but there is some support in Kenneth Harkness's Official Chess Handbook, "Approved by THE United States Chess Federation", David McKay Company, Inc., New York, 1967. One of the games illustrating descriptive notation goes 1 P-K4, P-K4; 2 N-KB3, P-Q3; 3 B-B4, P-KB4; 4 P-Q4, PxKP; 5 NxP, PxN; 6 Q-R5ch, K-Q2; 7 Q-B5ch, K-B3; 8 QxP(5), P-QR3; 9 P-Q5ch, K-B4; 10 B-K3ch, KxB; 11 Q-Q4ch, K-N4; 12 N-B3ch, K-R4; 13 Q-R4 mate. The caption to the third diagram on p. 94 reads (emphasis added) as follows:

  Position after 7 ...K-B3; 8 QxP(5). It is not advisable to write QxP, relying on the omission of check. QxP(5) shows that the Queen captures the Pawn on White's fifth rank.


Could Karjakin have grabbed on g5 at move 56 against Anand in the Candidates 2014?

3...h3 is wrong. The key is 3...Kf6!

[FEN "8/8/5k2/4p3/4P1Pp/4KP2/8/8 w - - 2 4"]

Note that:

White's king has to stay in the h-pawn's square, so it can't try to walk around the pawns.
Once white's king gets to h3, black should always be able to answer ...Kg5. If he does, then white's king can only retreat, unless he tries f4 there:

[FEN "8/8/8/4p1k1/4P1Pp/5P1K/8/8 w - - 8 7"]

1.f4 exf4

If anyone is better off here, it's black, but it's still a draw.

Or white can play 4.f4 immediately.

[FEN "8/8/5k2/4p3/4P1Pp/4KP2/8/8 w - - 2 4"]

4.f4 h3! 5.fxe5+ {What else?} Kxe5 6.Kf3 h2 7.Kg2 h1=Q+ 8.Kxh1 Kxe4 =

So the pawn endgame is a draw.


Resources to study benchmark opening positions, or "ideal setups"

I agree that in a well known opening Ideal positions may not be allowed by opponents, but this is not true when an opening is new and the strongest players are discovering the ideal (without the help of a computer)
When I was learning the King's Indian Defense I played through many games from the 1940's and 50's by Bronstein, Geller, Gligoric, Najdorf.
For Queen's Gambit, the 1910 - 1930 are good years to look at.
Also, learn the Tabiyas of your opening.  Many good opening books have a page or chapter on the key positions to understand in that opening.  This is part of what makes them good.  I keep a document of the Tabiyas of all the openings I play with short notes on the plans for both sides in that position.


Do FIDE rules ban stimulants? Which ones?

FIDE (and probably most of the national federations) would very much like chess to be an Olympic sport because that would lead to massive injections of money into the sport. Hence they subscribe to WADA and have defined drug testing protocols for chess.
The document Chess WADA – Anti-Doping Policy, Nutrition and Health gives details of banned substances relevant for chess:

The 2018 WADA Prohibited List and Monitoring Program can be found at:
http://list.wada-ama.org/
The most relevant banned substances for chess are:

Amphetamines – e.g. Adderall, Ritalin

Ephedrine and Methylephedrine – Prohibited by WADA when its concentration in urine is greater than 10 micrograms per milliliter

Pseudoephedrine is prohibited when its concentration in urine is greater than 150 micrograms per milliliter

Modafinil

Substances not present on the Prohibited List but represented in the Monitoring
Program:

Caffeine – Included in WADA Monitoring Program and relevant for incompetition testing only. Any urine test reading of less than 12 micrograms per milliliter poses no problem.
Codeine – A common ingredient in, for example, preparations used to treat coughs and stomach upsets. Any dosage is highly unlikely to be significant when taken in normal therapeutic quantities.

You say:

I hope they ban smoking somehow now.

Smoking is obviously banned in the playing area but is permitted in the playing venue if there is a designated smoking area. This is actually spelled out in the COMPETITION RULES section of the FIDE Laws of Chess:

11.3.4 Smoking, including e-cigarettes, is permitted only in the section of the venue designated by the arbiter

Not every tournament will have a designated smoking area although tournament organizers generally try and also not discriminate against smokers and vapers.

what can players take to stay alert and play better ?

The first and most obvious requirement for full mental alertness is adequate good quality sleep. FIDE has published its recommendations in Effects of Nutrition and Exercise on Cognitive Performance. There you will find FIDE's common sense guide to good nutrition and hydration.


What different time control rules are there in chess tournaments?

The FIDE-approved classical time control is: (taken from the handbook)

07 Time Control
There is a single time control for all major FIDE events: 90 minutes for the first 40 moves followed by 30 minutes for the rest of the game with an addition of 30 seconds per move starting from move one.

This time control is used in many major chess events such as the Olympiad, FIDE Grand Prix and World Cup.

Another popular international time control for classical is 90 minutes with a 30 second increment.

The classical time control used in the World chess Championship is: (from Wikipedia)
120 minutes, with 60 minutes added after move 40, 15 minutes added after move 60, and 30 additional seconds per move starting from move 61

Blitz time controls is simpler, with just two that dominate tournaments.

3 minutes with a 2 second increment is very popular in top level tournaments, being used in the recent World Blitz chess Championships and most, if not all the top level blitz events, this is because FIDE wants to avoid wins on time, to preserve the quality of top-level chess and also because there are significant prize funds at stake.

5 minutes is the most popular however, as it is easier to schedule as the games can only go as long as 10 minutes, whilst with an increment in can take a while.

For Rapid

15+10 (15 minutes with a 10 second increment) was the time control used in the recently concluded FIDE World Rapid and Blitz chess Championships.

25+10 Is very popular in top level rapid chess and all around as well, it was used in the World Cup in 2013 for the rapid tiebreak stage.

25 This is the most popular for the same reasons as 5 is for blitz.

This is for the rest of the world.

For the United States, its a whole different story,

http://archive.uschess.org/ratings/info/time.html


What is "spaced repetition" and how can I use it to improve my chess?

Spaced repetition is a learning technique that repeats content after increasing time spans according to learning success, i.e. faster for stuff you haven't grasped yet, longer if you do well.

In chess this is either used to learn a certain set of (easy) tactical exercises basically by heart ("woodpecker method" according to Axel Smith, Michael de la Maza, …), which is supposed to improve your tactical pattern recognition.

Or it is used to learn your opening repertoire by heart. For example by using the software Chess Position Trainer.

In my experience both are probably beneficial, but I cannot offer more than anecdotal evidence. Also you should complement it with exercises that tax more than your memory.


Yes, the problem is known to be cooked. The problem is actually a total win for White without a joke promotion.
Therefore, the task of creating a position in which the only way to win is to promote to a Black queen is an open one.
The problem can be found in the Die Schwalbe Chess Problem Database, or Schwalbe PDB for short. The solution engine there actually supports promotion to enemy units. The German notation means this: K=King, D=Queen, T=Rook, L=Bishop, S=Knight, and B=pawn.
The problem is that the normal promotion move 1. exf8=Q+, supposedly refuted by the study, actually wins for White!
[Title "Gyula Breyer, Magyar Sakkvilag, 1918, White To Play And Win"]
[FEN "1N1bknbr/2p1Pn1p/2K1Rp1p/4pP1B/p3p3/p3P1N1/P6P/8 w - - 0 1"]

1. exf8=Q! Kxf8 2. Kd7! {This is the move that Breyer missed!}

The problem is for Breyer’s study is that after 1. exf8=Q+ Kxf8, the move 2. Kd7 more or less leaves Black in a zugwang.
Furthermore, after the joke promotion to a Black queen, the position is indeed a draw as you noted. Stockfish analysis confirms this.
[FEN "1N1bkqbr/2p2n1p/2K1Rp1p/4pP1B/p3p3/p3P1N1/P6P/8 b - - 0 1"]

 1... Qe7 2. Nd7 Qxe6+ 3. fxe6 Be7 4. Nf5 Kd8 5. exf7 Bxf7 6. Bxf7 h5 7. Bc4

The inherent problem with the promotion to a black queen is that Black does not have to play, after  1... Qe7 2. Nd7 Qxe6+ 3. fxe6, 3... Ke7? as Breyer claimed in his analysis. This ends up in a loss for Black in the form of a mate in 5 moves.
(Note that the move 1... Be7? loses to a mate in 5: 1... Be7? 2. Kxc7 Qg7 3. Nxe4 Qg1 4. Nxf6+ Kf8 5. Nbd7+ Kg7 6. Ne8#)
[FEN "3bk1br/2pN1n1p/2K1Pp1p/4p2B/p3p3/p3P1N1/P6P/8 b - - 0 3"]

3... Ke7? {This is an incorrect move, contrary to Breyer’s analysis} 4. Nf5+ Ke8 5. Kb7 Be7 6. Kc8 Bd8 7. e7 Bxe7 8. Ng7# {This is the shortest mate afterward as found by Stockfish}

The correct line for Black to play is 3... Be7! and White has no mating net, thereby drawing the game, as given in your line I showed at the top of this answer.
It is a mystery exactly how the ingenious Breyer missed this possibility in his analysis. The most likely answer, through analysis of Black’s options after 4. Nf5, is that Breyer thought that Black must give up protection of their c7 pawn through a bishop move.
Black has 6 legal moves after 4. Nf5-5 by the bishop and one by the king. The moves Bf8 and Bd8 both lead to a mate in 5: 4... Bf8 Kxc7 Bd6+ 7. Kc8 Bc7 8. Nxf6+ Kf8 9. e7# (among many possible lines) and 4... Bd8 5. h4 Be7 6. Kxc7 Bd6+ 7. Kc8 Bc7 8. Nxf6+ Kf8 9. h4#. Bb4 and Bc5 both lead to shorter mates in 4 with the same basic ideas.
The move 4... Bd6 looks like a tempting refutation but White still wins even after that move. Here is one such winning line for White.
[FEN "4k1br/2pNbn1p/2K1Pp1p/4pN1B/p3p3/p3P3/P6P/8 b - - 0 1"]

4... Bd6 5. h4 Kd8 {Anything else results in a mate in 4} 6. exf7 Bxf7 7. Bxf7 Kc8 8. Nxf6

The end result is a positional win for White, although any normal person would struggle win of course.
The last, only non-bishop move 4... Kd8, therefore, is the ultimate refutation in this study after the joke promotion that Breyer somehow miscalculated.

TL;DR: In conclusion, Gyula Breyer’s joke study is cooked on two faults. A normal promotion actually wins after the line 1. exf8=Q+ Kxf8 2. Kd7!, and Black is in zugzwang
Secondly, in the joke promotion lines after the moves 1. exf8=Black queen Qe7 2. Nd7 Qxe6+ 3. fxe6 Be7 4. Nf5, Black can play the only non-bishop move 4... Kd8! and draw the game.
Overall, the study is refuted by a king move from each side. Therefore, it seems like Gyula Breyer could not, to some degree, properly analyze king moves in the endgame!


Judit Polgar Vs Nigel Short. Youtube video

It is probably part of this collection, which has the footage available from the 1994-1995 season.  It costs money though...


What books and videos would you recommend to an absolute beginner of Chess?

Absolute beginner? My best advice to you would be getting/buying Chess Master Grand Master Edition game. Install the Josh Waitzkin Academy (it will ask you while you're installing it's easy to notice) and go through his tutorial.

It's an interactive tutorial that teaches you how to start thinking as a chess player, it's completely voiced and will have puzzles and questions as it goes from one level to another forcing you to put what you just learned into practice. When you finish the entire tutorial, you should have at the end at least basic knowledge about openings (including some traps and how to avoid them!) middle game tactics and some sacrifices and last but definitely not least basic understanding of end game.

At the start it will even have you slightly practice memorizing the chess board annotations (like where b4 is or any other square) which definitely helps in the long run when you go into higher levels of chess.

After you're completely done with this tutorial and master it (you will most likely watch it more than once throughout your chess career to understand everything completely 100%) there is another course, which is less of a tutorial and more of a high level analysis between a GM and a ferocious Chess machine.

I advise you to not just watch and finish these tutorials but to also go out and play with other people... If there's a chess club out there near you or at least you can reach by bus or something, definitely go there and play against stronger players and you'll improve even faster.

Hope I helped :)


https://play.google.com/store/apps/details?id=com.google.android.chess&hl=en

Chess for Android has it, and it's the more or less industry standard for running engine matches on an Android mobile device.

I'm not sure if Droidfish can do it, somebody else might answer you.


In Nakamura v. Friedel in 2009, (22. Bc1) why did Friedel resign?

22...Rd2 saves the queen, but black is still down a massive amount of material. After white takes the rook on d2, he has two rooks for just a bishop. With such a huge material deficit, there is no possible hope of defending with normal play. The only chance for black would be to have an immediate attack on the king or other very strong compensation, which is not the case in the game. White's king is slightly open, but black has no way to take advantage of it and white can easily cover any threats to his king. Since black has no meaningful way to generate any play to make up for the material, he resigned.


How many games to play in a chess match?

The amount of games in a match is usually* even, to guarantee an equal balance between White and Black. 2 game (mini)-matches are rare, except in knock-out tournaments like the Chess World Cup. More games will produce a more reliable result, so you should play as many games as you have time for, but 4 games should already give a good indication about who's the better player. With some mathematics and the expected performance formula you can calculate the odds of losing an X-game match to a player who is Y ELO points better/worse than you.

*: The only exception is an Armageddon game which can be used after a match which ended in a draw (i.e. the same score for both players).


How to proceed with the book "Pawn Structure Chess" by Andrew Soltis?

I'm not familiar with the book itself, but for learning pawn structures it isn't important to memorize every single thing. The key is to understand the general ideas behind each structure. E.g.: what are the main plans, which pawns are weaknesses, what squares work well as outposts for pieces, can the structure be changed as the game goes on, etc.

Knowing these things would be useful if you were playing a real game with the structure in question. And the key is to know them, not to memorize them by rote. If you can understand why certain structures give rise to certain characteristics, then you could generalize when facing a new structure over the board.


What's a good website to study recent grandmaster games?

Chessgames has all the games from recent top GM tournaments.

Chess24 has live transmissions of the top tournaments.

And the Opening Tree at Chessok has opening variations with statistics and engine evaluations.

You can also find a lot of opening material on Chess.com, ChessPub or blogs like the Kenilworthian.


Would move sealing make sense in chessboxing? Or do the chessboxing people explain why they don't have?

No: I don't think move sealing would make sense in chess-boxing. I think it would disrupt the fluidity of movement between the two kinds of round, and introduce an asymmetry between what the two players have to do after the chess round.
Nor does the current situation give a significant advantage to the player on the move. Neither side has a chance to analyze the chess while engaged in the boxing which demands their full concentration. And can they can’t consult their friends or computers.
What part of one’s consciousness does one need for different activities? Speaking personally, I can drive safely while listening to radio at the same time. However I can’t navigate while doing both of those things. Where do chess and boxing overlap in brain function? My initial guess is that it’s best to focus on one at a time, with the main benefit of the boxing time for the chess is to refresh my mind so
I maybe see something different.
The only time in my humble little life that I was called upon to fight for real (the famous night of my grandmother’s 80th birthday, when I was ambushed with my brothers and cousins by a bunch of louts as we came out of a nightclub) time slowed down - I had infinite time to think as I moved without conscious decision between the other apparently frozen fighters. Who knew that I could behave in this way? It was surreal, and fortunately no-one was armed. I say this not to boast but to illustrate that in genuine peril, emergency circuits can be engaged although I wouldn’t have wanted to play chess at the same time.
I can see advantages in being the last to play in a chess round, and also not being the last to play. Particularly as the match goes on and both players begin to deteriorate in concentration, forcing the opponent to be the first to play in the next chess round makes it more likely that they will make a slip.
Simillarly, setting up a trap at the end of a chess round could be an excellent trick. Will it be spotted by the opponent when they are just sitting down and getting focused.
Nor, as I mentioned in a comment, do I think that the last punch should be sealed between boxing rounds! The dislocation between rounds of chess and boxing is all part of the sport.
To see this sport at the top levels, here's a clip of Chessboxing World Championships.


No way. I would resign if I were Black. This is a hopeless position - game over. Anybody other than a total beginner would win for White.

However if:

Black's pawn is a rook or bishop pawn
Black's pawn is close to promotion
Black's king is close to the pawn
White's king is far away from the pawn

It'd be possible to draw by stalemate.

  https://chess24.com/en/read/news/7-stalemates-every-chess-player-needs-to-know

Note: colour reversed in the examples.

King + rook pawn vs. queen

7K/7P/6q1/8/8/1k6/8/8 w - - 0 1

King + bishop pawn vs. queen (variation)

7K/5P2/6q1/8/8/3k4/8/8 w - - 0 1


Is it important to have chess as part of the education in schools?

The Telegraph ran a story supporting the benefits of learning chess. Here is the summary for the 'for' camp:

  Pupils as young as seven should be given compulsory lessons in chess amid claims it boosts concentration levels, numeracy and reading comprehension, according to a teachers’ leader.

From the limited research I've done, articles like this do not highlight the 'against' camp, so I will construct my own argument for why chess may not be included on the syllabus:

Limited class time. Class time could be spent on existing subjects (reading, writing, arithmetic), or spent on many other worthy 'new' subjects (computing, citizenship, financial awareness etc.). It becomes a trade off between what we want to teach the next generation with the limited time they have in school
Uncertainty of transferable skills. In the quote above it's claimed that chess improves numeracy skills. But surely studying mathematics would be a more direct way to do this?
Level of popularity. In the UK, football/soccer is arguably the national sport. There just wouldn't be many pupils that would want to study chess, nor many teachers of a suitable callibre


You cannot get a definitive answer, but in all likelihood, 99.99% it is a draw no matter who is to move (I am the type of person, who never says I am positive unless there is 100% proof, and that is impossible here, however likely).

The overwhelming factor in this position is that the black bishop does not control the a1 square, so even if white had no pawns, it would be a draw. It is clear that white can also never break the blockade either if black just plants his king on c6. It would remind me of an opposite color bishop blockade, but white has no bishop. Just Kc6, and Bd5-h1 with an easy draw.

The only reasonable exception would be if somehow white played a5, and later was zugzwanged into having to play b5 (like eventual stalemating the king on a1, forcing b5. That said, just avoid a5 (white can actually play b5 right now if on the move to avoid that issue).

It seems like a pretty easy draw either way to this long-time Master.

P.S. My Stockfish at a depth of 48 still reads 0.00


Is my improvement decent, and if so how can I keep it up?

Going from a beginner to being rated 2200 on Lichess in a year is a very good rate of improvement. Would you mind elaborating on what you did to get there?

Still, a Lichess rating isn't always an accurate representation of strength, and it's possible you could be somewhere between 1600-1800 ELO over the board. The only way to find out is to play rated games OTB and see. This could be useful in figuring out how to continue your training.

For continuing, it seems like whatever you're doing is working well (I wouldn't worry about trying to accelerate your progress, if anything it will start to decelerate soon). If you really are 2000-2200 strength, you could consider getting the GM Preparation books from Quality Chess. The Great Predecessors series by Kasparov is also recommended. In addition, you should put together a solid opening repertoire, perhaps using Chessbase. You can buy opening books to do this, or research on your own (you might need help at first if you've never done it before). A good endgame book would be useful as well. I assume you're already doing this, but solving online tactics is important for sharpening your tactical intuition. You could also consider finding a coach in your area, but this depends on how much you want to spend to reach your goals.

Most titled players took years to get where they are, so I wouldn't give yourself the pressure of reaching their level so quickly. For example, I only got my FM title after playing for roughly 12 years. Building up a good intuition (which helps in blitz) comes from lots of practice, and isn't really something that can be gained very quickly.


What color squares should pawns be on with one bishop left?

The rule of thumb is that the stronger side (the side trying to win) should put the pawns on the opposite color of his or her bishop (so that they don't get in the way), and the weaker side should put pawns on the same color as their bishop in order to defend them an extra time (defended with the bishop and the king, the opponent can never win a pawn).

There are obviously exceptions to this, though.  Each position really has to be judged independently.

One key idea, however, is that it is usually a good idea to block your opponent's pawns on the same color as the bishops (assuming that the two bishops are both light squared bishops or both dark squared bishops).  This gives you the chance to try and win the pawn later and it will restrict the movement of your opponent's bishop.

If you have the only bishop on the board (your opponent has a knight, for example) it is almost always correct to put the pawns on the opposite colored squares of the bishop.  This is usually the only way to play for a win.  This touches on the good bishop/bad bishop question, but if your bishop is bad, then the knight will many times have the edge.  If your bishop is good, however, you can try to make use of the bishop's superior range.


The tactics trainers cannot be compared to each other.
You need to compare them to a specific person as everybody has different needs and preferences.
That said, all the ones I have seen are done poorly from an educational perspective which would most effectively help you improve as fast and as far as  you could.


How often does each side win in Rook, Bishop and Knight versus Queen?

The best resource I know for endgame statistics is the ICGA spreadsheet at https://ilk.uvt.nl/icga/games/chess/endgames.php. The spreadsheet posted there contains pretty much all 6-man endgames. So for example KRBNKQ is found in row 277 (assuming White has RBN), with the following percentages:

       wtm    btm
W win 51.35  9.45
 draw 45.13 49.27
B win  3.52 41.28

So the result is highly dependent on who has the move.

EDIT: Clarifications (1) This is a tablebase based on computer analysis of all possible positions with these 6 pieces. It does not refer to actual games played over the board. (2) The spreadsheet refers to "non-broken positions" which approximates to "legal positions".


Is there an archived video with commentary of Norway 2015 blitz tournament available on the official or other websites?

Blitz video now seems available at http://livestream.com/chess24/norwaychess2015


Yes. You will still be detected just that the site is going to need more games. You are more likely to stay under the radar, but that doesn't mean you won't be caught. Cheat detection has never been just comparing your moves against the computer.
To understand, online cheat detection is an application of anomaly detection in data science (google "Anomaly Detection" if you need help). Chess.com calculates dozen of metrics such as the probability of beating a higher rated opponent due to luck, and many other metrics that they will never tell you. They are also going to do it for everybody in the database. Once they do it, they will then have a distribution of the metrics for each rating group.
If you are a smart cheater, you will win games slower than a dumb cheater but still more statistically significant than everybody else not cheating. Chess.com will create a mathematical model such as hypothesis testing to derive a p-value probability of you cheating given a null hypothesis that you aren't a cheater. As you win more and more games, the standard errors of your profile will get smaller and smaller, your p-value will also get smaller. It will just be a matter of time until chess.com bans your account.
Even if you don't end up winning, your in-game performance such as your ability to stay consistent with the top-three computer moves or your ability to play time-pressure high complexity positions while not blundering will be statistically different from everybody else in your rating group. Chess.com will be able to detect you even if your moves don't match with the computers.
That's exactly how you see why cheaters like Dewa Kipas were able to cheat for a few weeks until his match with IM Levy Rozman. (https://www.chess.com/news/view/most-watched-chess-stream-in-history-dewa-kipas). Chess.com needed time and data to build up Dewa Kipas's cheating portfolio.
You will be caught given a high enough number of games, but a single game won't be enough.


It is a common problem to calculate all the variations and then suddenly realize that the first move was simply terrible. Actually, there is a rule that should be applied after finishing a complicated calculation, the Blumenfeld rule!

The Blumenfeld rule is formulated roughly as follows. After finishing a complicated calculation, take a fresh look at the position on the board. Try to picture the position directly after the next move you plan to make. Check whether you are missing something trivial. Are you perhaps losing a piece after this move? Are you missing a simple check that makes you lose material? Perhaps you will even be checkmated in a few moves? Only after completing this check for terrible blunders can you now go on and make your move.

This rule does not come easy to any player at any level!


Rook ending with single distant passed pawn

This should be a draw as far as I know and the first step is to get behind the pawn with your rook. Now if black pushes the pawn to the second rank it is an easy draw, because he can never move the rook without you taking the a-pawn and if he tries to protect the a-pawn with the king you will just give checks from behind.

8/R6p/6p1/8/8/1k5P/p5PK/r52 w - a6 0 33

In this position you just check with Rb8+ and go on checking until his king leaves the a-pawn. Then you go straight back to attacking the a-pawn otherwise Rh1+ wins for black.

So what he might try is pushing the pawn only to a3. Then he has a place on a2, to hide his kings from the checks. But now the problem for black is that he doesn't threaten to move his rook away and queen the pawn, therefore your rook isn't shackled to the a-pawn. That means as soon as his king leaves the kingside pawns, you just snatch them off with your rook.

8/8/R5p1/5k1p/7P/p5K1/6P1/r52 w - a6 0 33

Something like …Ke4 Rxg6 Kd4 Rg5 Kc3 Rxh5 Kb2 Ra5 ...

Given that his king has to run all the way to the a-line, then move the rook and make two pawn moves to queen the pawn, this should give you enough time to push your own kingside pawns. When you finally have to give your rook for the a-pawn, ideally your kingside pawns (supported by your king) are so far advanced that his rook cannot deal with them.


Is Magnus Carlsen ever going to play against Stockfish in a event?

I don't think it'll ever happen because:

Who's going to pay? Deep Blue was covered by IBM, Deep Fritz was covered by Chessbase, but Stockfish is a free open-source engine.
It's not fun for Carlsen to play an odd match with Stockfish, but he will likely be beaten convincingly if the match is fair.
Human vs computer in chess is not interesting anymore. The focus has shifted to Go and Poker.

It's not going to happen.


Is it ethical to tell your opponent how you are going to checkmate them?

It is not a question of ethics, but more about being courteous.  Chess is a game where it is impossible to separate the joy of the game from the competitiveness/ego aspect so by declaring a forced win in N moves, you are effectively asking your opponent to resign immediately even though he hasn't seen the forced win yet owing to his lesser faculties/skill set.

Try doing that kind of thing at work/real life .. you'll be out of a job in no time (or get punched in the face) :)

Your opponent may be weaker than you and he may not be able to calculate like you do, but give him the chance OR let him play the game out till the bitter end.  You can't just force somebody into resigning by brow-beating them, for God's sake :)

Beyond the probability (however small) that you may be wrong / You may have missed an in-between move or desperado yourself, you are essentially coming off as a jerk. The rare exception is that you are coaching somebody (as part of a mutually agreed session, not one where you suddenly decided to act like a coach! ) where you can afford to point things out to them and not come off as arrogant.


It seems to me you have the idea spot on already. Traditionally, chess theory was that the best way to control the center was to occupy it. Some players (like Nimzowitsch and others) showed that this was not necessarily true and that there is merit in letting your opponent occupy it while you undermine it from a distance.

I'm not sure if the idea was really novel at the time, but it became popular and as we do whenever we see a pattern we have to name it.

Beyond that I doubt there is much to learn from "hypermodernism" (which is not to say that there is not much to learn from the various rich and deep ideas behind each of the so labelled openings themselves).


Sir Jeremy Morse, in Chess Problems: Tasks and Records, Introduction, cites this construction by E. Luukonen:

[Title "E. Luukonen, Uusi Suomi, 1936"]
[fen "kr6/pnPPPPPPPP/P2N4/R7/3BBN2/1Q6/3K3P/6R1 w - - 0 1"]
[StartFlipped "0"]

All of White's 117 moves lead to mate in 2. White has no mate in 1, but if Black's rook were to move, or if (after White captures that rook) Black's king were to recapture, White then has a mate. Thus a waiting-move is enough.


When he is mating, is he just following a method blindly or does he understand it?

For instance in the two examples you mention, zugzwang and opposition are important themes, which are also relevant to many endgames. You can find many easy pawn only endgames with these motifs and since they are so fundamental, I'd start with these motifs. Somewhat related, triangulation, key/corresponding squares could also go here. All of these you can do in pawn endgames which, because of the few options you have, are generally easier to understand than if you add any other pieces.

Some more specific topics could be king and rook-pawn vs king (draw/stalemate), mating with two bishops (which is not all that difficult if you understand that two bishops can build something like a "wall" that the enemy king cannot cross and your own king can relatively easily push the enemy king to the border), square rule to quickly assess whether a king can catch a pawn before promotion.

If you think that these are too complicated at his current level, I'd forget about endgames for the time being and focus on opening/middlegame play.