Is it beneficial to play themed practice games? While practicing, is it advisable to play themed games? For example, playing practice games using the Sicilian Defence, or the French Defence.

I play at an intermediate level. I have chess.com rating of around 1500. I have never read or studied any chess books.

It really depends on what your end goal is. Themed games in a specific opening are good to get familiar with a specific opening, and get a "feel" for the positions arising in the resulting middlegames. So, if you want to learn a new opening, or are having trouble in a certain line, it could be a great way to learn an opening, coupled with studying some opening theory (on the 1500 level the amount of opening theory needed isn't that great, and a few lines together with some basic knowledge of ideas in the opening usually is enough).

However, if you want to become a stronger player all-round, I would say that it's an inefficient training method in and of itself, and should be used as a supplement, rather than your main means of exercise. You will learn more studying tactics and analysing your games, since tactics will be an area any 1500-level player can improve, and practicing analysis is key to being able to improve later on. But of course - play chess! That is probably the single most important means of training available, since it gives you more experience. And playing some of these games in a pre-arranged opening line will not be a waste.


Poor gambit for white I was white and played this against a 1589 rated player on Lichess.

The gambit happens at move 10 and it is characterized as a blunder by stockfish analysis. However, black does some inaccuracies and after a couple of moves he is trapped. Black does a blunder on move 13, and black cannot avoid being checkmated. It looks obvious from the analysis that black should have used the other pawn.

Are there any more experienced players that could tell me some of the possible moves that black can do to avoid getting into trouble and also what white can do instead of taking the risks that i took after move 10. I am wondering what white should do after realizing the gambit was a blunder.

[fen ""]
[Event "Hourly Blitz Arena"]
[Date "2019.02.23"]
[Round "-"]
[White ""]
[Black ""]
[Result "1-0"]
[Variant "Standard"]
[TimeControl "300+0"]
[ECO "B21"]
[Opening "Sicilian Defense: Smith-Morra Gambit"]
[Termination "Normal"]
[Annotator "lichess.org"]

1. e4 c5 2. d4 { B21 Sicilian Defense: Smith-Morra Gambit } cxd4 3. Qxd4 Nc6 4. Qd1 Nf6 5. Nc3 d6 6. Bb5 Bd7 7. Nf3 a6 8. Ba4?! { (-0.03 → -0.56) Inaccuracy. Best move was Be2. } (8. Be2 e6 9. O-O Be7 10. Bf4 Qc7 11. a3 O-O 12. h3 b5) 8... b5 9. Bb3 b4?! { (-0.34 → 0.50) Inaccuracy. Best move was e6. } (9... e6 10. Qd3) 10. Bxf7+?? { (0.50 → -2.95) Blunder. Best move was Nd5. } (10. Nd5 e6 11. Nxf6+ Qxf6 12. O-O Be7 13. a3 bxa3 14. Rxa3 Ne5 15. Nd4 d5 16. exd5 Bxa3) 10... Kxf7 11. Ng5+ Kg8 12. Nd5 h6? { (-3.82 → -1.07) Mistake. Best move was e6. } (12... e6) 13. Nxf6+ exf6?? { (-1.26 → Mate in 2) Checkmate is now unavoidable. Best move was gxf6. } (13... gxf6) 14. Qd5+ { Black resigns. } 1-0

I'm an FM so I guess I'm experienced. For Black's POV, the 12...e6 variation you gave is the best way to play. It pretty much stops White's attack and Black's just up a piece. If he really wanted to Black could have also gone for 11...Ke8 followed by ...e6. In any case, playing with ...e6 is the way to go since it covers up all Black's weak light squares.

For you, I'd recommend not going for 3.Qxd4 (it's rather dubious). If you want to go for this kind of setup, consider playing 2.Nf3 and after 2...d6, 3.d4 cxd4 4.Qxd4. Of course you couldn't go this after 2...Nc6 though. If you still want to play 3.Qxd4, consider 4.Qe3 followed by 5.c4. It gives you a bind in the centre at least.

After 9...b4 in the game, you should have played 10.Nd5. You're a bit worse, but at least the game is close to equal. After 10.Bxf7, I think you played well to get compensation. I wouldn't recommend playing safe AFTER 10.Bxf7, since you need to attack to make up for being down a piece.


Resources for annotated or commented games by level of audience Similar questions have been asked before here or here. Still I think it would be more useful to have these resources listed by level. There is not much point for a beginner to listen to a GM explaining long lines and deep positional ideas. Similarly an advanced player does not want to learn about how the knight moves. So the question is:

What are freely available resources for annotated or commented games and in what category of audience would you put them?

I am looking for:

written and audio and video
names of players/streamers...
names of concrete events (e.g. banter blitz with ..., commentary on tournament... by ...)
can overlap levels but preferrably not cover more than two levels

So just saying chess24 is not enough as that includes a whole range of levels.

For the levels I suggest the chess.com system (but am open to alternatives) In any case that would be just a rough guideline:

beginner <1400
intermediate  1400 - 2000
expert 2000 - 2200
Master 2200+

Hanging Pawns has quite a few videos that annotate GM games, and I'd say they're probably intermediate to maybe expert (using your format)
Agadmator has a ton of videos annotating GM games (often released mere hours after the game finishes!) I'd say probably beginner-intermediate on your scale.
Note that both of these channels annotate after the game, not during.


Would you look for mate, if tactics to win materials are easier to spot? I'm black, I defeated a 1830 very easily in a 11 + 10 game and I had plenty of time, but I played fast and didn't see mate, he was low on time. Analyzing with lichess engine

[fen "2k2r2/ppp5/7p/3Pp1p1/3n4/2PPK1B1/Pq4PP/R3R3 b - - 0 1"]

1... Nc2 (1...Rf4!)

The engine suggested Rf4 and mate in 3, I played Nc2. And here

[fen "2k2r2/ppp5/7p/3Pp1p1/4K3/2PP2B1/Pqn3PP/R3R3 b - - 0 1"]

1... Nxa1 (1...Qb6!)

I missed Qb6, mate in 4 and played Nxa1. Again I had plenty of time on the clock, around 10 minutes, the opponent was so easy to beat, but that's not the point, the point is I missed mate twice, I just wasn't looking for it.

Now that I look at it, I think I would  never play Rf4, Yes the king is trapped but there's so much material on the board to take, I don't think I would have analyzed the Rf4 line, not in this life, nor the next one.

When faced with such winning positions, in a blitz match, do you go for materials or do you stop and analyze possible mating lines? I just want to know if I'm being a humain or am I not seeing those lines because I'm weak or careless.

if I'm in losing position or equal position, I analyze many lines trying to win, but games like these I try to simplify and reach a simple endgame.

It makes no difference whether you deliver mate in 3, mate in 33 or your opponent resigns. On the score sheet and the tournament results you get the same score: 1-0. If you see a clear win then play it. Don't waste time looking for a "better" win. There is no such thing unless you are in a hurry to catch the last bus home.

Fixating about what the computer says in such positions is just silly. This is not just my opinion it is also shared by top players. I am currently reading Boris Gelfand's "Positional Decision Making in Chess" and he expresses this view in the book in positions where he is pursuing a positional winning plan and the computer analysis points out a quicker tactical win.


How to improve my game I am doing tactics 30 minutes a day, practicing end games for about 90 minutes and analyzing 1 GM annotated game a day.

I can understand the logic behind why the move is played, but I can't apply it in my own game. I can't understand what the position is asking. I can know my opponent is making a mistake but I can't find a way to punish it.

My Elo rating is 1335.

Are there any books to solve these problems?

Not any good books, as most use tactics as the only guide. however you can practice yourself.  Solitaire chess, where you try to guess the move--and the reason--before reading it from the annotated game, is the best practice, yet has the major flaw of not considering every style of play.

A must read for everyone is Nimzovitsch's My System.  Botvinnik's game are useful for showing how to maneuver, which is useful for exploiting positional mistakes.

Thinking Techniques (written by Dr. Ferguson ~ 1982)

BEFORE EVERY MOVE...THINK:

What new threat(s) has my opponent's last move created?  How can I answer it(them)?
Is my King safe?  Is my opponent threatening to checkmate in the next few moves?  Can I checkmate my opponent?
What threats can I set up?  How?
Have I seen this position or a similar one before?
If so:  who stands better, and what is the best plan for continuing?
If not:  what are the outstanding features and elements of this position, and what plan(s) and method(s) of achieving it are available?
What is my plan?  What specific position would I like to obtain?  How can I achieve my goal? How can I improve my position?
Which move is best?  Can I capture material without penalty? Can I employ an tactical device?
Is it safe to move my piece to the square I'm thinking about?
Did I remember to start my opponent's clock and write down my move?

Not as useful as I hoped, but without a game example or more definite  problems, it's hard to provide a specific answer.


What is the main idea in this winning endgame? I was playing an online game with the white pieces and won the exchange in the middlegame. So I exchanged some pieces and went for the "winning endgame". I went ahead to draw the game. Afterwards, I analyzed the game and the Lichess analyzer showed that I had +1.8 advantage in this position.
[Title "White to move"]
[fen "B7/3R2p1/4pk2/2p2p2/Pb3P1p/4P1P1/2b4P/6K1 w - - 0 41"]

I want to know what is the best strategy here to take advantage of my rook over Black's bishop. I figure my bishop should by in the same diagonal my passed pawn, so 42.Bc6 seems like a good continuation, so black responded with 42. ...h3, now my king is somewhat trapped by Blacks bishops, and they are too active, I do not have enough time to make my rook guard the a5 square so that I can push my pawn. So what should I be rooting for in this position? How to activate my king?

Interesting position;
Activating your king I don't believe is the answer. I think your first goal is try and force the the c2 bishop off the board. corner the black king and create as many potential promotion threats (a , e and h files particularly)
I played the position out for a while on a few variations and will attach the cleanest variant;
I see the main objectives for white though is to try and lock blacks king on the right hand side and or rear of the board, try and remove potential promotion threats. Black black bishop is relatively harmless and is tied to the c5 pawn. Preventing the c5 pawn from promoting or moving will also keep the b4 bishop from being active in the game. Slowly whittle down the right side of the board which creates to many promotion opportunities that overwhelms blacks defenses.
[Title "White to move"]
[fen "B7/3R2p1/4pk2/2p2p2/Pb3P1p/4P1P1/2b4P/6K1 w - - 0 42"]

1. Bc6 h3 2. Kf2 g5 3. Rb7 gxf4 4. gxf4 Kg6 5. Be8+ Kh6 6.Rb6 Kg7 7. Rxe6 Kf8

Key Moves:
gxf4 by capturing towards the center, you keep the b4 bishop not being able to cause any impact to whites pawns on the E through H files. Any attempts will result in a loss of material. In addition to this the c2 bishop is quite an inactive piece in this position
[Title "White to move"]
[fen "4Bk2/8/4R3/2p2p2/Pb3P2/4P2p/2b2K1P/8 w - - 0 8"]

8. Bd7 Bb3 9. Ra6 Bd5 10. Be6 Be4 11. Ra7 Ke8 12. a5 Bd3 13. a6 Bxa6 14. Rxa6 Bc3 15. Rc6 Bb4 16. Bxf5 Kf8 17. Bxh3 Kg7

Key Moves
Be6 support by the rook on a6, white has no means of capturing the without trading out its only useful bishop. The bishop is also somewhat "shepherding" the king with the a6 rook. It is also positioned attacking the c8-e3 diagonal poised to take out blacks pawns and threaten promotion.
Ra7 Locks the king to the d8 , e8 , f8 squares.
a6 forces black to capture with the bishop otherwise white can easily promote to queen and then mate.
To summarize

Blacks b4 bishop is tied to the c5 pawn. Blacks only potential promotion threat can be largely ignored.
Keep up pressure. This is preventing Black from doing any meaningful development. Black is forced to move and lose pieces in this position.
Prevent Black from activating their king.


Names of all Gambits I am interested in knowing the names and moves for all named gambits in chess.

If anyone has such a list or knows where I can find one please do pass it on to me. Please be sure to include names of gambits that black plays as well as white and all counter gambits.

I think your best bet will be the ECO (or Encyclopedia of Chess Openings)

The following is a complete list of all gambits in the ECO.

Polish Gambit 1. e4 b5
Wing Gambit 1. e4 c5 2. b4
Ware Gambit 1. a4 e5 2. a5 d5 3. e3 f5 4. a6
Birmingham Gambit 1. b4 c5
Schuhler Gambit 1. b4 c6 2. Bb2 a5 3. b5 cxb5 4. e4
Wolferts Gambit 1. b4 e5 2. Bb2 c5
Englund Gambit 1. d4 e5
Budapest Gambit 1. d4 Nf6 2. c4 e5
Benko Gambit 1. d4 Nf6 2. c4 c5 3. d5 b5
Staunton Gambit 1. d4 f5 2. e4
Smith-Morra Gambit 1. e4 c5 2. d4 cxd4 3. c3
Danish Gambit 1. e4 e5 2. d4 exd4 3. c3
Vienna Gambit 1. e4 e5 2. Nc3 Nf6 3. f4
King's Gambit 1. e4 e5 2. f4
Quaade Gambit 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Nc3
Kieseritsky Gambit 1. e4 e5 2. Nc3 Nf6 3. Bc4 Nxe4 4. Nf3
Rice Gambit 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. h4 g4 5. Ne5 Nf6 6. Bc4 d5 7. exd5 Bd6 8. 0-0
Elephant Gambit 1. e4 e5 2. Nf3 d5
Latvian Gambit 1. e4 e5 2. Nf3 f5
Irish Gambit 1. e4 e5 2. Nf3 Nc6 3. Nxe5?
Halloween Gambit 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5?!
Blackburne Shilling Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4
Italian Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. d4
Rousseau Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 f5
Evans Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. b4
Blackmar–Diemer Gambit 1. d4 d5 2. e4 dxe4 3. Nc3
Queen's Gambit 1. d4 d5 2. c4
Grünfeld Gambit 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 0-0


Could White win this rook-endgame? [Event "FIDE Women's World Chess Championship"]
[Site "Sochi RUS"]
[Date "2015.03.23"]
[Round "3.1"]
[White "Marie Sebag"]
[Black "Natalia Pogonina"]
[Result "1-0"]
[ECO "C65"]
[WhiteElo "2482"]
[BlackElo "2456"]
[PlyCount "177"]
[EventDate "2015.03.17"]
[FEN ""]

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. O-O Nd4 6. Nxd4 Bxd4 7. c3 Bb6 8.
Na3 c6 9. Ba4 O-O 10. Bg5 h6 11. Bh4 Bc7 12. Bc2 b5 13. d4 d6 14. Bd3 g5 15.
Bg3 Qe7 16. Re1 Bb6 17. Nc2 Bd7 18. h3 Rfd8 19. Qf3 Ne8 20. Rad1 Ng7 21. Bf1
Bc7 22. c4 a6 23. Ne3 Re8 24. b4 Rad8 25. d5 Rf8 26. dxc6 Bxc6 27. cxb5 axb5
28. Bxb5 Ba8 29. Bc4 Bb6 30. Ng4 Kh7 31. Nf6+ Kg6 32. Nd5 Bxd5 33. Rxd5 Ne6 34.
Qf5+ Kg7 35. h4 Nd4 36. Qg4 Rc8 37. Bd3 Rc3 38. Rd1 Ra8 39. Bb1 Rc4 40. Kh2
Rxb4 41. f4 exf4 42. Bxf4 Qe6 43. Qxe6 fxe6 44. Bxd6 exd5 45. Bxb4 dxe4 46. Bc3
Ra4 47. Bxe4 gxh4 48. Rb1 Bc7+ 49. Kh3 Be5 50. Bd5 Kf6 51. Rb4 Ra3 52. Bb3 Nxb3
53. Bxe5+ Kxe5 54. axb3 Ra2 55. Rxh4 Rb2 56. Rb4 Kf5 57. g4+ Kg6 58. Kg3 Rb1
59. Kf4 Rf1+ 60. Ke5 Rb1 61. Kf4 Rf1+ 62. Kg3 Rg1+ 63. Kf3 Rf1+ 64. Kg2 Rd1 65.
Rb5 Rd3 66. b4 Rb3 67. Kf2 Kf6 68. Rf5+ Kg6 69. b5 Kg7 70. Rc5 Kg6 71. Rd5 Kf6
72. Rc5 Kg6 73. Ke2 Kf6 74. Rf5+ Kg6 75. Kd2 Rb4 76. Kc3 Rxg4 77. Rc5 Rg1 78.
Kb4 Rb1+ 79. Ka5 Ra1+ 80. Kb6 h5 81. Kc7 h4 82. b6 h3 83. b7 h2 84. b8=Q h1=Q
85. Qg8+ Kh6 86. Rc6+ Kh5 87. Qg6+ Kh4 88. Rc4+ Kh3 89. Qg4+ 1-0

With 56. Rh6 , white could transfer in a won endgame. And black slips in move
81 (instead of 81... h4? the move 81 ... Ra5 would have drawn). Could white
win the rook-endgame before move 77 without the slip 55 ...Rb2 ?

Well, according to 7-man tablebase your analysis is correct:

Rxh6 would win, reaching a Lucena position.

81...h4? was a mistake, ...Ra5 was the only drawing move.
Neither player made a mistake in between those two points.

Also, Black could have made it more difficult with 86...Qxc6+, reaching QvR which can be hard to win. White didn't have to allow that possibility.

Of course, there's a big difference between checking tablebase, and giving useful advice to use during a game.  I guess we could say that White should really have seen the chance to go into Lucena; and Black must have miscalculated something when playing ...h4 -- or possibly overlooked the Ra5 plan (it is unusual).


Source of this chess problem? [FEN "8/8/8/6pp/6pk/R7/6KP/8 w - - 0 1"]

1. Rh3+ gxh3+ 2. Kf3 g4+ 3. Kf4 g3 4. hxg3# 1-0

What is the source of this simple chess problem (White to mate in four) which somebody showed me at a chess club 50 or 60 years ago?

I suspect it's from the very early days of chess because it's so simple (no variations), and because of the unfashionable checking key, and because it involves only moves which have never changed in the history of chess (no queens or bishops or double-step pawn moves).

I tried searching the Meson Chess Problem Database and Yet Another Chess Problem Database without success, not sure I did it right.

I happened to find the position in an old book: on page 87 of "The Basis of Combination in Chess" by J. du Mont.  The diagram is shown with the names "Rubinstein vs N.", without date and place. Probably a game in a simultaneous exhibition.  The book was first published in 1938 and Dover reprinted it in 1978.


Where can I find a whole bunch of complicated PGN files? I'm interested to test that the atom syntax highlighter for pgn files -- https://atom.io/packages/language-pgn -- can handle the full range of possible files.  Is there a suite of difficult test files somewhere?

Also related might be this question:

What are all of the possible tags for PGN?

As an author of some PGN-processing software, I would also be interested in having access to a general test suite but I am not aware of any, unfortunately, and all I can offer is some advice based on experience.

I would be wary of throwing a large database of games at an application in order to test it before you have developed reasonable confidence with its fundamentals. In the early stages, at least, I find it most effective to create a lot of small examples, each of which tests an individual feature. That way, errors are relatively easy to spot because they don't get lost in a mass of output. Once I have got rid of the basic errors I would then look at combining a small number of both related and unrelated features in individual tests to make sure that there is no unexpected interference between the associated functionality. Only late on would I switch to large datasets to make sure there are no issues with scaling up.

I also highly recommend re-running all the existing tests each time a new feature is added. I have been amazed how often I have unexpectedly broken something seemingly unrelated as the code has developed.

Apologies if these principles are already well known to you!


Chess challenge #10: A beautiful knightmare This time I bring you a beautiful composition. White is down material but is about to queen the d7 pawn. The only problem is the knight fork on f7 and if he doesn't act very quickly Black is going to put his bishop on a5. How does White win the game?

[fen "8/3P3k/n2K3p/2p3n1/1b4N1/2p1p1P1/8/3B4 w - - 0 1"]
[Title "White to play and win (Gijs van Breukelen, 1997)"]

I stumbled upon this composition in this blog and I found it extremely beautiful. The composer is Gijs van Breukelen.

My semi-educated guess at a solution:

   1.Nf6 Kg7 2.Nh5 Kg6 3.Bc2+ Kxh5 4.d8Q Nf7 5.Ke6 Nxd8 6.Kf5 e2 7.Be4 e1N 8.Bd5 c2 9.Bc4 c1N 10.Bb5 Nc7 11.Ba4 and Bd1 should lead to mate. It's all pretty forcing, at the beginning black has to avoid blockading f7 or stepping into d8Q+ and then the bishop starts threatening mate all over the place until black runs out of knights ...


Transposition Tables Are transposition tables (in engines) used for one or multiple games?

My current knowledge of transposition tables is that when an engine searches the game tree, there will sometimes be positions that have already been calculated earlier. A transposition table allows an engine to take what it already had calculated earlier and use it for even deeper search.
What I don't understand is whether transposition tables store positions permanently (such that an engine can use what it previously calculated in previous games for new games) or if it's strictly game-specific as in that a new game corresponds with a completely empty and new transposition table.

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.


In the Dubois-Steinitz match (1862), at what point does the match become irreversibly lost for White? And why does the engine not pick it up early? I am a beginner player (~1400 rating on lichess). I was studying a famous match between Dubois and Steinitz shown below (analysis done by Stockfish on lichess.org). My doubts are:

1) At what move does the game become "bad" for White? Is it the 9. Nxg5 move? Or is it some move further downstream? After Black plays 12...Nd4 was there any possible move that would have saved White?

2) Why doesn't the Stockfish engine pick up the fact that Black is winning until the very last moment when White plays 13.Nc3 ? According to engine analysis, 8...h5is an inaccuracy for Black, 9.Nxg5 is a mistake for White, and 10...hxg3 is a mistake for Black! More surprisingly, till 12...Nd4 the engine considers White slightly better (or rather neutral) at +0.3, and in the White's next move it suddenly says checkmate is unavoidable and suggests  13.Ne6 to be better for White. But even with 13.Ne6, black can still play 13...Nf3+ and so on, and win the game.

[fen ""]
[Site "https://lichess.org/OtJ2x5RY"]
[Date "London 1862"]
[White "Serafino Dubois"]
[Black "Wilhelm Steinitz"]
[Result "0-1"]
[ECO "C50"]
[Opening "Italian Game: Giuoco Pianissimo, Normal"]
[Termination "Normal"]
[Annotator "lichess.org"]

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 Bc5 { C50 Italian Game: Giuoco Pianissimo, Normal } 5. O-O d6 6. Bg5 h6 7. Bh4 g5 8. Bg3 h5?! { (-0.08 → 0.50) Inaccuracy. Best move was Na5. } (8... Na5 9. Bb3 Nxb3 10. axb3 a6 11. c3 O-O 12. Nbd2 Ba7 13. Nc4 Be6 14. Ne3 Kg7 15. b4) 9. Nxg5? { (0.50 → -1.08) Mistake. Best move was h4. } (9. h4 Na5 10. Nbd2 Bg4 11. Bb3 Nxb3 12. axb3 Bxf3 13. Nxf3 g4 14. Ng5 Qe7 15. c3 O-O-O) 9... h4 10. Nxf7 hxg3? { (-0.83 → 0.38) Mistake. Best move was Qe7. } (10... Qe7) 11. Nxd8 Bg4 12. Qd2 Nd4 13. Nc3?? { (0.31 → Mate in 7) Checkmate is now unavoidable. Best move was Ne6. } (13. Ne6 Ne2+ 14. Qxe2 Bxe2 15. Nxc7+ Kd7 16. Nxa8 Bxf1 17. Bb5+ Ke7 18. Nc3 Bxd3 19. Bxd3 gxf2+) 13... Nf3+ 14. gxf3 Bxf3 15. hxg3 Rh1# { Black wins by checkmate. } 0-1

Playing the game on lichess.org, I only need to wait for a few dozens of seconds to reach the following analysis for White ninth move:

9. Nxg5 is an interesting counter-attack move that ultimately fails to bring an advantage but white is not lost. After 12. ... Nd4 13. h3! Ne2+ 14. Qxe2 Bxe2 15. Ne6 White survives.

Since 13. h3! saves White, 13. Nc3?? is indeed a fatal blunder. 13. Ne6?? also yields a mate in 7 for black.


What is considered a distraction to an opponent? My questions concern section 12.6 of the FIDE rules handbook (http://www.fide.com/component/handbook/?id=124&view=article) which states that it is forbidden to distract or annoy the opponent in any way.

Imagine that Player A and Player B play each other and Player B complains to the arbiter that some action of Player A is a distraction. My question is about when the complaint is reasonable. My view is that in some situations, Player A's action is legitimate and for others, the arbiter may ask Player A to oblige. For the situations below, is Player A's action legitimate or not?

2.1 Player A leaves the table (not the hall) - it is Player A's turn to move.
2.2 Player A stands behind Player B's chair on Player A's turn.
2.3 Player A stands behind Player B on Player B's turn.
2.4 Player A plays without sitting down - it is player A's turn.
2.5 Player A is seated and fidgets continously.
2.6 Player A stares continually/makes faces at Player B.
2.7 Player A does not write down the moves.
2.8 Player A's mobile phone is switched off but its alarm rings. Will Player A be forfeited?

Quite a few of these are already covered elsewhere in the rules. In the rest it would be up to the arbiter to use his judgement. I will quote the rules where relevant and state what I would have done as an arbiter.

2.1 Player A leaves the table (not the hall) - it is Player A's turn to move.

Explicitly covered by article 12.2:

  12.2
   Players are not allowed to leave the ‘playing venue’ without permission from the arbiter. The playing venue is defined as the playing area, rest rooms, refreshment area, area set aside for smoking and other places as designated by the arbiter.

  The player having the move is not allowed to leave the playing area without permission of the arbiter.

So player A is free to leave the table, but not the playing area.

2.2 Player A stands behind Player B's chair on Player A's turn.

This type of behaviour is not explicitly covered outside of article 12.6, but unless player A was doing something unreasonably distracting like leaning over player B, I don't see a big problem with this, however if player B does make a complaint about being distracted by it I may ask Player A not to do so. It's at the arbiter's discretion.

2.3 Player A stands behind Player B on Player B's turn.

2.4 Player A plays without sitting down - it is player A's turn.

2.5 Player A is seated and fidgets continously.

These are all pretty similar and would be handled as for 2.2, it would be at the arbiter's discretion to decide what if any action to take about it.

2.6 Player A stares continually/makes faces at Player B.

This time the behaviour is clearly distracting and the arbiter should take action if the behaviour can be proven or was seen by the arbiter. If player B makes this complaint and I/other witnesses did not see player A doing anything wrong, I could not take any action directly, but would make sure to observe player A from then on to see if any such behavior takes place.

2.7 Player A does not write down the moves.

Explicitly covered by article 8.1:

  8.1 In the course of play each player is required to record his own moves and those of his opponent in the correct manner, move after move, as clearly and legibily as possible, in the algebraic notation (See Appendix C), on the scoresheet prescribed for the competition.

  It is forbidden to write the moves in advance, unless the player is claiming a draw according to Article 9.2, or 9.3 or adjourning a game according to the Guidelines of Adjourned Games point 1.a.

  A player may reply to his opponent’s move before recording it, if he so wishes. He must record his previous move before making another.

  Both players must record the offer of a draw on the scoresheet. (See Appendix C.13)

  If a player is unable to keep score, an assistant, who must be acceptable to the arbiter, may be provided by the player to write the moves. His clock shall be adjusted by the arbiter in an equitable way.

So both players are required to write down the moves anyway.

2.8 Player A's mobile phone is switched off but its alarm rings. Will Player A be forfeited?

Explicitly covered in article 12.3:

  12.3 ...
  Without the permission of the arbiter a player is forbidden to have a mobile phone or other electronic means of communication in the playing venue, unless they are completely switched off. If any such device produces a sound, the player shall lose the game. The opponent shall win. However, if the opponent cannot win the game by any series of legal moves, his score shall be a draw. ...

So yes, player A would be forfeited. The rules state only that the device needs to make any kind of sound for the player to be forfeited.


Fun variants in teaching chess to children I'm teaching my 5 year old daughter basic chess. While she's kind of interested, I feel the material, such as how the pieces move, mate in 1 puzzles, basic KQ and KR checkmates, etc, is a bit boring to her.

This answer on another question presented an interesting variant call Rescue Snow White. It combines piece move training with some fun story.

Can someone can suggest other variants similar to Rescue Snow White that motivate children to learn chess? Being fun on the chess board is the main requirement, while the training value is an optional bonus.

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.


Advancing the c6 pawn in the Caro-Kann I am having trouble understanding when Black should move c5 in The Advanced Variation of the Caro-Kann.
I have posted two games of mine below:

In this first game, after the seventh move of White, the computer has no quarrel with the pawn advance c5 (though I played Ne7).
However, here:

Which is a really similar position, if I play c5 (on the 8th move),Stockfish tells me it is not the right thing to do, but rather I should have played Ne7 which is a move also acceptable in the former position.

My question is: does anyone know when is the advance c5 appropiate? I cannot see any reason why these positions should be differently evaluated at all.

I mean in the second position I find no particular reason why playing c5 which in case of being captured allows the direct development of my kingside bishop can be a bad thing at all.

The knight on c3 is the difference.  In the second position, White can exploit superior development by quickly opening the centre with c4.  It's not easy for Black to arrange castling.


What are the different training strategies for different player strengths? What are the key training areas (Openings, Middlegames, Tactics, Strategies, Endgame, Studies, etc) and tools (books, computer engines, databases, etc) in which players of different levels of playing strength (for instance 1800, 2100, 2400, 2500, 2600, Elo rating etc), should focus on in order to improve their chess to the next level of understanding and playing strength?

First, this outline is more for the average player, who still may be very decent, but is not likely to be become a professional.

Beginners up to 1800, it is mostly about tactics: Tactics, tactics, and more tactics. I also found that having a very strong dose of endgames, even when I got my first rating of 1036 USCF back in 1980, has stuck with me all the way through being a Master. I still love Fine's "Basic Chess Endings" (any mistakes in it as far overshadowed by the principles that it puts forth).

Around 1800, people start getting more clued in on positional play, and start picking up more on that. I still love Ludek Pachman's trilogy: "Complete Chess Strategy". That was the first time I started to see real plans enter into my games, and I still credit that trilogy with making me a Master. For the first time, I started to really grasp pawn play.

Also, around 1800, I also think that players need to understand HOW to play opening pawn structures instead of focusing on memorizing openings that when their opponent deviates, they are lost and on their own. For this, books like Soltis' "Pawn Structure Chess" (a really bad book if you are looking at it with a computer, but the underlying principles are very strong), and Mauricio Flores Ríos' book "Chess Structures: A Grandmaster Guide" is a fantastic book that expounds upon what was in the Soltis book, and does it a lot better, but also at a higher level.

Starting at 2000, assuming you have a shot at 2200 and higher, you are going to start needing specific openings, and memorization as you face stronger competition. All along, you should have been still studying more and more endgame material as you will also need that when you faces "monsters".

Over 2200, you are talking about in-depth refinement of what you have learned. A lot of people buy the Dvoretsky books before they are ready, and now is the time that you are just getting started to be ready for those. They will help with small details, and a lot of it above 2200 is analyzing better and better, so not only will his books refined and expand your knowledge, they are hand-picked difficult problems that need a lot of deep analysis.

Once at 2400, if you have not already had a professional coach, you probably will need one to really gain a lot more strength. In addition, if you have a kid, who is super talented, and clearly going places, it is also probably a good idea for them to have a professional coach at a lower rating, and younger age to get the most benefit.


How can one get the best possible result against a player of very different strength? I (about a 1500 player) once took White against a 2100 player, and played a Queen's Gambit. I lost of course, but the other player complimented my play. He said, "You played well for about 20 moves, and made a small mistake on the 21st, which I took advantage of."

It certainly helped that I was playing White, which is sort of a form of handicap.
(See Is there a way to use handicaps in chess to bridge the gap between players of different skill levels?)

I don't remember using a "book" variation, but played moves that seemed to follow common sense. Maybe I kept the game simple. Somehow, I managed to play "neck and neck" until I overlooked a combination that gave Black a pawn advantage.

Is it as simple as that, staving off defeat is a matter of not making mistakes? (I finally made one, although it wasn't obvious to me.) Or does the weaker player (with White, anyway) have to do something to keep the stronger player at bay, like seize and hold the initiative (which I tried, but probably failed to do)?

And to reverse the question, suppose you were playing someone of much less rated strength who was playing "even" with you, perhaps as the result of learning some book variation. Should you steer for complications, perhaps away from the book, into areas that your opponent might be less familiar with? Or should you just play your best game and count on him to make a mistake?

Statistically speaking, a 600 point rating disadvantage means that you have about a 3.07% chance of winning.  If you want to improve that, your best bet is to play a position that you are familiar with.

This part of the answer might be more pertinent to a 2000 player playing a 2200 player
One way to do this is to play an opening that you know intimately.  If you have a pet line, this is the time to play it.  Especially if you've analyzed an unusual opening with a computer, this will shorten the odds.  Basically, the 3200+ rated computer will be playing your opponent for you.
Ok, that's it for opening preparation

One common suggestion is to randomize the position if you are the weaker player.  This makes a lot of sense.  Chances are that the stronger player is also better at endgames.  So you don't want to get to the endgame unless you will win easily.  I've frequently beaten lower rated players from an equal endgame or even an endgame where I'm a little worse.

In a "randomized" position, usually multiple pieces are hanging, one or both kings are weak, and most of the pieces are still on the board.  Now, unfortunately, truly good players thrive in these positions, and they will work out all the complications.  But you're probably not playing a 2600+ grandmaster, so this is still not a bad idea.  In these random positions, both players will be forced to use most of their time to make their way along the "narrow path".[1]  Once the players are deep in time pressure, anything can happen.[2]

This is NOT to say you should make bad moves.  If at any point you make inferior moves, well, the stronger opponent will probably take advantage of them.  Instead, just keep pieces on the board.  One trick you can use to complicate - when a piece is attacked, instead of moving it or defending it, just attack one of your opponent's pieces.  This is much easier said than done, but this will quickly complicate even a mundane position.

Ok, if you've made it this far, just a few more general thoughts.  The easiest way to beat a stronger player is to just get lucky.  Everyone has a bad day from time to time, you just have to be playing someone who happens to make a mistake and take advantage of it.  The key to this is to not make any terrible mistakes.  If you can stay in the game and not lose material, you can always win - even if you have a bad position.

Double check every move before you make it.  If you see a move that you think wins, spend more time than usual, don't make this move quickly.  If you're right, being behind on the clock won't really matter.  If you're wrong, you won't make an inferior move.  One saying that I've always found helpful is "never play a blunder quickly" (source unknown).

Personally, I'm not convinced that the right plan is to just complicate the position and hope.  While this is a good plan of last resort, everyone plays with the same 16 pieces.  Make solid moves, calculate everything you need to, and be inspired to play well.  Even if you lose, you'll learn far more from a well played game that you just barely lost than a game where one of the players blundered on move 12.

Lastly, some rules that have helped me against lower rated players in the past:

Don't be afraid of endgames, even if it should be drawn with best play
Similarly, don't be afraid of equal positions
A small advantage is often enough to win, but even if you are down material, swindles are often possible, so don't give up.
Finally, as a stronger player, I've had good luck in complicated positions.  As likely as it is for a stronger player to blunder, it is even more likely for the lower rated player to also blunder.

[1]: David Bronstein: "When you play against an experienced opponent who exploits all the defensive resources at his command you sometimes have to walk time and again, along the narrow path of 'the only move'."
[2]: Lev Alburt: (paraphrased from http://www.amazon.com/Chess-Rules-Thumb-Lev-Alburt/dp/1889323101) "Having 15 minutes when your opponent has 5 is worth 200 rating points."


What is the best strategy for simultaneous blindfold chess? Recently, Timur Gareyev displayed tremendous prowness by playing many boards blindfolded. What is the best strategy to visualize each and every board?
I already know the basics, like splitting the board into 4 parts, adopting different techniques for each stage of the game (opening, middlegame, and endgame), trying to visualize the board, and recognizing patterns or ideas.

How do I scale it up for many boards?

This question involves the human mind's memory, so to start, let's play a quick game. Look at the line below for 1 second, and then look away immediately.

G R T A O H V I L P

Now try to recall as many of the letters as you can.

Now do the same thing for the next line (look for 1 second):

Fish Table Plate Water Mouse Cookie Scroll Piece Fan Ball

Recall as many of the words as you can.

The number of letters you were able to remember is probably close to the number of words you remembered. This is because human minds chunk many small things into bigger things, if given the opportunity. Words are just letters being chunked together. Note though, that if you didn't know what "Cookie" is, chances are you wouldn't have remembered it (since your mind wouldn't have had the opportunity to chunk C,O,O,K,I,E into one word).

This process can be applied to chess positions. You want to give your mind more opportunities to chunk pieces ("letters") into positions you can memorize ("words"). The key to doing this is pattern recognition; training your mind to immediately recognize positions (or immediately chunk certain arrangements of pieces together). Pattern recognition is just like learning new words in a language.

The best way to improve pattern recognition abilities is to look at many chess positions, over and over and over. Solving puzzles is a great way to do this since your mind is actively thinking about positions, allowing them to be stored and accessed easier from long-term memory. This not only helps your chess playing abilities, but also how well you can hold many positions in your head. If you can immediately see arrangements of pieces and know that they're a certain position (like C,O,O,K,I,E means "cookie"), then all you're really doing is holding big words in memory.


Endgame theory question Let us look at an endgame where White has 8 pawns, and Black has the e/d-pawn missing. How can White win this endgame if both sides play perfectly? I am having a little trouble.

A more practical form of your question relates to the Exchange Lopez and Tartakover Caro-Kann.
Euwe did a complete analysis of how White wins the Exchange Lopez pawn ending if you set up the pawn structure with no pieces on the board:
4k3/1pp2ppp/p1p5/8/4P3/8/PPP2PPP/4K3 w - - 0 1

While the Tartakover Caro=Kann is the same thing on the other wing.
In this impractical 8-vs.-7 thing you envision, the side with the extra pawn would surely begin with the unopposed pawn two squares, as the first step toward creating a passed pawn.


Absolute strength and stability of Elo Not sure how to phrase this...
I am aware that Elo measures the relative strength of players.
Let's assume for this question that there is such thing as an absolute strength in chess and that players stay at their level without improving or getting worse over time.
If there are only two people in the pool playing many games against each other their Elo ratings will settle on some value and these values are a measure of their absolute strength.
Now, if there are more than two players, I was wondering, whether under the assumptions above (absolute strength exists, no change over time), the Elo ratings would also settle on constant values or would keep on changing constantly?
For the answer, I would like to exclude chess arguments like: player A cannot deal with player B's aggressive style and scores worse than against other players of the same rating (but who play more calmly).

Basically I am wondering whether there is some kind of analogue to frustration (physics term) in the Elo system, namely that, if you have >2 players in a pool they would not happily settle on a rating.
To put it concretely, I am wondering whether the system of players ends up in a steady state of constant player ratings such that if at that point in time any two players play against each other a million games, their outcome reflects exactly their rating difference.
It is assumed that players are of comparable strength so that they have a non-zero probability to draw (or win).

No. In the general case, the ELO ratings of three people will not converge to some stable equilibrium, and here's why.
Suppose you have two players, A and B. B on average scores 66% vs A, so if they played enough games, B's ELO rating would converge to about 100 more than A's.
Now suppose we introduce player C, who scores 66% vs B on average, but never plays against player A.  If C and B play many games, their ELO difference will stabilize to about 100 as well.  If B kept playing games with A during this time, A would converge to about 100 less than B, with C about 100 more than B.
So, what happens when A finally starts playing C? For there to be stability in the ratings, we MUST have C score 76% vs A, because C is 200 ELO points higher than A.  If A scores better than that, A would gain points when playing C, causing the gap between A and B to decrease.  But then A would lose the points A gained if they started another long series with B.  In this case, the three ELO ratings are not only a function of how well they play against eachother, but also how often they play each opponent - clearly not an absolute rating in any sense.
So this begs the question, if B beats A 66% of the time, and C beats B 66% of the time, should we automatically assume that C beats A 76% of the time, as the ELO functions imply?  That doesn't sound too crazy, but for the 3 body ELO problem to be stable, this implied score would have to be accurate for ANY pair of ELO gaps between A-B and B-C.  There aren't any assumptions in the ELO model that this transitivity should work.


Understanding Anand's Bc4 move vs Ivanchuk 1992 In the Ivanchuk vs Anand game (1992), the game leads into an endgame after lots of exchanges, which by no means looks (to me at least) winning for black: they both have 2 rooks, 2 bishops, and black has a rather awkward pawn structure in the center with the doubled f-pawns and the light square holes. Nonetheless, Anand decided to trade his bishop by playing Bc4 (shown in diagram below), and managed to win the game afterwards quite convincingly and rather seamlessly!

But what is Anand's plan with the move Bc4? And how is it that black could suddenly build such a strong edge in the endgame thereafter?

Diagram:

 [title "Ivanchuk vs Anand 1992"]
 [fen "1r2k2r/4bp2/p2pbp2/1p2p3/4P1P1/P3B3/1PPR3P/1K3BR1 b k - 0 20"]

 1...Bc4

In short, the key idea is to prevent white from playing h2-h3!

Bc4 forces the exchange of light square bishops, and thus, sets up Rh3 which blocks the h2 pawn and keeps both the h2 and g4 pawns weak.
Concretely, the only piece currently covering h3 is the light squared bishop on f1, so by trading the bishop with Bc4, which white cannot prevent as Bg2 leaves h2 hanging, white has no immediate means (e.g. a rook on g3 would prepare h3 but it's too slow) of preventing black's imminent Rh3.

Black's bigger idea is to create two connected central passed pawns!

More precisely, the plan is:

to pressure g4, and binding white's rooks to the defense of g4 and h2,
bring the king to e6 to prepare the d5 advance to trade the e4 pawn, then go back to e6 and similarly prepare trading white's g4 pawn with f5,
after which black is left with a passed f and e pawn, that is, two connected passed pawns!

Suppose Bc4 is not played, then white gets to play h3, and thus maintaining their bind on light squares and killing black's prospect of
creating two connected passers.
In the game itself, Ivanchuck decided to trade the g-pawn quickly (by advancing it to g5) in order to get rid of one of his weak pawns, after which Anand still managed to execute his plan as all he had to ensure was trading the e4 pawn by playing d5. Here's the position that transpired in the actual game, where Anand's plan has been executed to perfection:

Quite an exemplary game showing Anand's deep positional understanding: note the move Bc4 a priori undermines a couple of chess principles:
it willingly trades black's only good bishop, after which black is left with a hemmed-in dark squared bishop vs white's active one. Moreover, black allows
their queenside pawns to become shattered into 2 (isolated) islands, and in doing so having less chance of dominating1 2-vs-3 on the queenside.

In spite of all these at-first-glance-unfavourable aspects of the move, Anand beautifully realised controlling the h3 square outweighs them all, since preventing white's h2-h3 pawn advance to support g4 is the only way black can maintain the prospect of active play in the pawn skeleton that had transpired, as we discussed above.

Here's the game itself:

 [title "Continuation after 20...Bc4"]
 [fen ""]
 [startply "40"]

 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. Qd2 a6 8. O-O-O h6 9. Be3 Nxd4 10. Bxd4 b5 11. f3 Qa5 12. a3 e5 13. Be3 Be6 14. Kb1 Be7 15. g4 Rb8 16. Nd5 Qxd2 17. Nxf6+ gxf6 18. Rxd2 h5 19. Rg1 hxg4 20. fxg4 Bc4 21. b3 Bxf1 22. Rxf1 Rh3 23. Re2 Kd7 24. g5 Ke6 25. gxf6 Bxf6 26. Bd2 Be7 27. Be1 f6 28. Bg3 d5 29. exd5+ Kxd5 30. Rf5 Kc6 31. Ref2 Rh6 32. Kb2 Kd7 33. Re2 Bd6 34. Rf3 Rc8 35. Be1 Ke6 36. Rd3 Rh7 37. Rg3 Bc5 38. Ka2 Rd7 39. Rc3 Rcc7 40. h4 Rd1 41. Bf2 Bd6 42. Rg3 e4 43. Rxe4+ Be5 44. Rxe5+ fxe5 45. Kb2 Rd2 0-1

1: Domination in this context means: the side with the minority (less pawns) achieving a setup (e.g. a blockade) where neither of the majority pawns of the opponent can (easily) advance. Typical to the Sicilian pawn structure on the queenside, one such setup could be white's pawns being on a2-b3-c2 and black's pawns pinning down on dark squares with a5-b4. For an example see the setup by Caruana (as black) in his candidates game vs Karjakin (e.g. around move 22), where indeed one of his positional mistakes in that game was to give up the domination with 26...a4.


A New Year's Math Riddle Here's a fun and clean riddle for the New Year! I found the material for it on Krabbe's site. I will provide the link when it is solved.
How many times can this position be repeated, with both sides helping, before either side can claim a draw repetition? No cheating, please!

Addendum 1/7/20201: With the acceptance of the answer, here is the link to Krabbe's AD magazine article "TWEEëNTWINTIG FOTO'S," which translates to "Twenty Two Photos."

The board layout can be repeated at most 11 times with White having the move, the 12th will be a draw.
[FEN "rnbqkbnr/1pp2pp1/4p3/p2pP2p/P6P/8/1PPP1PP1/RNBQKBNR w KQkq d6 0 1"]

1. Be2 {White can no longer capture en passant.} Be7 2. Bf1 Bf8 {2nd time} 3. Be2 Be7 4. Bf1 Bf8 {3rd time}
5. Rh2 {White can no longer 0-0} Be7 6. Rh1 Bf8 {4th time} 7. Rh2 Be7 8. Rh1 Bf8 {5th time}
9. Ra2 {White can no longer 0-0-0} Be7 10. Ra1 Bf8 {6th time} 11. Ra2 Be7 12. Ra1 Bf8 {7th time}
13. Be2 Rh7 {Black can no longer 0-0} 14. Bf1 Rh8 {8th time} 15. Be2 Rh7 16. Bf1 Rh8 {9th time}
17. Be2 Ra7 {Black can no longer 0-0-0} 18. Bf1 Ra8 {10th time} 19. Be2 Ra7 20. Bf1 Ra8 {11th time}

However (emphasis mine):

9.2.2  Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same.

So:
[FEN "rnbqkbnr/1pp2pp1/4p3/p2pP2p/P6P/8/1PPP1PP1/RNBQKBNR w KQkq d6 0 1"]

1. Bd3 Bc5 2. Be2 Bf8 3. Bf1

is not a repetition of the original position (it's Black's turn now), although it is the same board layout.
Therefore: the position can be repeated 10 times (excluding the initial position), multiply this by 2 (2 more times the layout can be repeated with Black's turn) and add 1 (the initial position) + the final repetition on which the draw is claimed = 22 times.


When you're up in material In some games, I was up on material, but then lost due to either time pressure or blunders. How should I avoid these type of pitfalls?

I see two things you can consider:

trying to learn how to control your stress.
playing many faster games to get used to play and think more quickly (if you often play games with 15 minutes per side, try to play games with 10 minutes per side).

Therefore you most probably won't often be in this situation anymore.


Is a piece hanging if it is defended by a higher value piece? In this extreme examplethe c5 pawn is defended three times, though white can take the pawn with an advantage.

 [FEN "2r1k3/2r5/2q5/2p5/8/8/PPR5/KN4B1 w - - 0 1"]

What about if the defender is a higher value piece than the attackers, even though it's defended and attacked twice? Clearly, White can take the pawn with an advantage.

 [FEN "8/8/3k4/2p2q2/8/8/PPR5/KN4B1 w - - 0 1"]

Now it's not hanging:

 [FEN "8/8/3k4/2p2r2/8/8/PPR5/KN4B1 w - - 0 1"]

What do you call these type of situations if it's not hanging piece?

This position also has a hanging piece:

[FEN "2b4k/3q2pp/8/5p2/8/2B1N3/PP6/KN4Q1 w - - 0 1"]

This would still be called a hanging piece. If the piece can be taken with impunity, it is a hanging piece. It is irrelevant how many attackers there are on the piece, how many defenders there are on the piece, or the point value of the attackers/defenders.


Why are the requirements for becoming a GM so complicated? Wikipedia's article on chess grandmasters indicates that the requirements to become a GM is complicated, and has always been complicated. For example right now, to become a GM, one needs to have had a rating of at least 2500 at some point in one's career, and one needs "two favorable results (called norms) from a total of at least 27 games in tournaments", with the rules for what qualifies as "norm" occupying several more bullet points (quotes from the WIkipedia article).
Why does it need to be so? If the aim is to award the title only to world class players, I can think of some much easier system to select them, e.g. you must have been rated in the top 100 of the world at one point. This would tie the title to a single, easily-understood number. I notice some of the lower titles already use this criterion (e.g. Candidate Master), so it begs the question of why the higher ones have more complicated requirements.

If the aim is to award the title only to world class players, I can
think of some much easier system to select them, e.g. you must have
been rated in the top 100 of the world at one point. This would tie
the title to a single, easily-understood number. I notice some of the
lower titles already use this criterion (e.g. Candidate Master)

The comparison with the Candidate Master title is a telling one. The CM title is not highly regarded. This has been covered in two previous questions here - How respectable is the CM title? and Is a candidate master considered a master?

Why are the requirements for becoming a GM so complicated?

They are indeed complicated. Here is the link for the FIDE Title Regulations effective from 1 July 2017. One additional requirement, which I don't see listed here, is that the tournament organizer must send a file with the PGNs of all the games for the tournament.
The reasons they are so complicated is that they have evolved over time to deal with the corrupting influences of money, politics, rating manipulation and cheating.
Money
One of the ways of getting the GM title is to be World Champion. Here is what Wikipedia says about the early period of world championships:

From 1886 to 1946, the champion set the terms, requiring any
challenger to raise a sizable stake and defeat the champion in a match
in order to become the new world champion.

So, no money - no match. As the article says, this had a profound effect on who got to play for the title:

This requirement makes arranging world championship matches more
difficult, for example: Marshall challenged Lasker in 1904 but could
not raise the money until 1907;[37] in 1911 Lasker and Rubinstein
agreed in principle to a world championship match, but this was never
played as Rubinstein could not raise the money.[38][39] In the early
1920s, Alekhine, Rubinstein and Nimzowitsch all challenged Capablanca,
but only Alekhine was able to raise the US$10,000 that Capablanca
demanded, and not until 1927

OK, you might be thinking, those kinds of considerations belong to a bygone age. Well, try telling that to Shirov who, perhaps, should have been World Champion in 2000 instead of Kramnik:

Soon after the 1995 championship, the PCA folded, and Kasparov had no
organisation to choose his next challenger. In 1998 he formed the
World Chess Council, which organised a candidates match between Alexei
Shirov and Vladimir Kramnik. Shirov won the match, but negotiations
for a Kasparov–Shirov match broke down, and Shirov was subsequently
omitted from negotiations, much to his disgust. Plans for a 1999 or
2000 Kasparov–Anand match also broke down, and Kasparov organised a
match with Kramnik in late 2000

Politics
This is what the Wikipedia article has to say on this:

Title awards under the original regulations were subject to political
concerns. Efim Bogoljubov, who had emigrated from the Soviet Union to
Germany, was not entered in the first class of Grandmasters, even
though he had played two matches for the World Championship with
Alekhine. He received the title in 1951, by a vote of thirteen to
eight with five abstentions. Yugoslavia supported his application, but
all other Communist countries opposed it. In 1953, FIDE abolished the
old regulations, although a provision was maintained that allowed
older masters who had been overlooked to be awarded titles

There was more political interference in the 1962 Candidates tournament which selected the challenger for the 1963 World Championships. Here is what the article says:

What makes this tournament famous and often-discussed is the
allegations of Soviet collusion. The three top finishers (Petrosian,
Geller and Keres) drew all twelve of their games against each other,
in an average of only 19 moves.[15]
Soon after the tournament, Fischer publicly alleged that the Soviets
had colluded to prevent any non-Soviet – specifically him – from
winning. His allegations were twofold: first, that Petrosian, Geller
and Keres had pre-arranged to draw all their games; and second, that
Korchnoi had been part of the drawing pact in the first half of the
tournament, and been instructed to lose some games to them in the
second half.[16][17][18] (In the first two cycles Korchnoi drew all
his games with Petrosian, Geller and Keres; in the third cycle he lost
to all of them; and in the final cycle he lost to Petrosian but drew
with Keres and Geller).
The first allegation, of the drawing pact, is generally assumed to be
correct.[18] All of the three players involved have since died, but
Yuri Averbakh, who was head of the Soviet team, confirmed it in a 2002
interview.[10] He offered the rationale that Keres was the oldest
competitor and wanted to conserve energy, and that Petrosian and
Geller were good friends with a history of drawing with each other.
The second allegation, of Korchnoi throwing games, is more
doubtful.[18] Korchnoi defected from the USSR in 1976, and never
alleged he was forced to throw games. Dominic Lawson calls the
allegation "preposterous", noting that the main beneficiary of
Korchnoi's losses was Petrosian, whom Korchnoi detested

Rating Manipulation and Cheating
There is an interesting Wikipedia article on this. For those who like their chess dripping with blood there is the story of infamous mother-killer Claude Bloodgood:

Bloodgood organized chess games within Powhatan Correctional Center in
Powhatan, Virginia, which were by necessity with fellow inmates.3
Many of these inmates were taught the game by Bloodgood, and thus
began as unrated and inexperienced players. Bloodgood obtained USCF
memberships for them. Some accused Bloodgood, with his intimate
knowledge of the rating system, of rigging their ratings. The
accusation was that he arranged for new prisoners to play rated games
against other prisoners, who would deliberately lose, thus giving the
new inmate an inflated USCF rating. Bloodgood, it is further alleged,
then played rated games against the new highly rated prisoner, and
each time he won, gained a few more rating points. This continued for
several years, and by 1997 his rating rose to 2759, making the
59-year-old Bloodgood the second highest rated player in the nation,
only behind Gata Kamsky.

OK, but that was USCF rating not FIDE. That could never happen with FIDE ratings, surely? And certianly not for titles? Well, check out this article from TWIC (The Week in Chess) from 8th March 1999. Here is an extract:

Respected Grandmaster and chess journalist Ian Rogers also felt moved
to comment on the event in the Canberra Times Chess Column for March
7th. He too was almost breathtaken by the number of norms scored in
the event and the calculated level of planning required for titles and
rating fraud on this scale. I quote, with permission, at length below.
"The Grandmaster tournament which took place in Rangoon in the first
two weeks of February took months of planning but succeeded in
creating six Grandmaster results and eight IM results, an astonishing
success rate. (Two or three title 'norms' are needed for a player to
be awarded the GM or IM title.) Some of those scoring Grandmaster
results had struggled to score 50% in the South-East Asian zonal
tournament only a month earlier! Corruption extended not only to the
tournament itself - with seven highly rated locals losing all their
games to their compatriots - but also to a series of events held in
1998 which provided extremely high world rankings for all those
required to be 'victims' in the February tournament. All seven of the
no-hopers in February were unrated in January 1998, yet on the January
1999 FIDE list had rankings higher than Australian Grandmaster Darryl
Johansen."
"The following game is not atypical of their play, with the heavily
'outrated' Mas winning one of the easiest games of his career: Rangoon
1999 White: H.Mas Black: Thein Dan Oo 1.e4 c5 2.f4 d6 3.Nf3 Nc6 4.Bb5
g6 5.0-0 Bg7 6.Bxc6+ bxc6 7.d3 Rb8?! 8.Nc3 Nf6 9.Qe1 0-0 10.b3 d5?
11.e5 Nd7 12.Ba3 Re8?! 13.Na4 Rb5 14.e6 Nf6? 15.c4 Ra5? 16.exf7+ Kxf7 17.Ne5+ Kg8 18.Nxc6 1-0 Mas, the honourable Malaysian IM who performed so creditably in Sydney in January, was not one of the favoured many
who scored title results. His opponent, rated 2539 - a near-GM
ranking, managed only 4 points from 14 games. There is no suggestion
that any of the foreign visitors were involved in anything other than
pre-arranged draws - they simply took advantage of the extraordinarily
overrated opposition. However the local players in Rangoon probably
knew the results of many of their games before the event began and if
an 'accident' occurred to one of those destined to score a title norm

e.g. a loss to a foreign player - their compatriots pitched in and provided some extra points or half points. Unusually for a corrupt
tournament, the foreign invitees were not needed to help out the
locals, since the enormous rankings of the weakest players meant that
the scores required for title results were relatively low."

"From the point of view of the organisers, the event was so successful
that it is likely to be repeated in a few months time, before the
ratings of the tailenders are adjusted on the July FIDE rating list.
After one more such tournament, Burma could have 4 Grandmasters and
half a dozen IMs; after a few more such tournaments they could have
more Grandmasters than any country in Asia! Publicity may encourage
the Burmese to become more discreet in future but FIDE is highly
unlikely to take any action. Their actions in past cases would
indicate that the world body tacitly approves of a 'developing' chess
nation acquiring titled players, whatever the ethics involved."


Extreme effort to keep a pawn backward I'm currently studying chess strategy, and I can across an example of backward pawn exploitation that I do not understand. The book I'm reading suggests 1... Rd5 to keep the d4 pawn backward. Doesn't that put the rook into a precarious position to be attacked by 2. Bxd5? Why is it so valuable to keep the d4 pawn backward?

For reference, I'm looking at the example on pg. 236 of Silman's "Reassess Your Chess", 4th edition.

[Title "Black to move"]
[StartFlipped "1"]
[fen "3r1rk1/1pb2pp1/p1p1pq1p/2P2b2/3PBP2/PPB5/2Q3PP/4RRK1 b KQkq - 0 0"]

1...Rd5

In this case, the pawn on d4 is not just a target.  It's also restricting white's bishop on c3.  For that reason, it's very important that black not allow white to sacrifice this pawn by playing d4-d5 when white would have very good chances to hold.

Black would like to trade off light square bishops and then put a rook on d5.  The immediate 1...Bxe4 2.Qxe4 Rd5 fails tactically because white can play 3.f5! with decent counterplay on the kingside.  Additionally, at least one pair of major pieces will be traded off after white plays f5, and generally speaking the side with the isolated pawn or backwards pawn wants to trade off major pieces.

After 1...Rd5!, white cannot take on d5 because the Be4 is pinned to the white queen.  Black will play 2...Bxe4 next move and then a move like g6 in order to stop white's f5 advance.  Black will be much better - nearly winning - because black can slowly bring the dark square bishop around to f6 or g7 where it will attack the d4 pawn.  Black will also double rooks on the d file.  White, in the meantime, has no constructive plans that don't create new weaknesses.


What chess *scoring* alternatives exist? Chess (often being classified as a sport) stands almost alone among sports in that its results are of a strictly ternary nature that is not quantified any further: The only possible outcomes are a win, a draw or a loss.

While the same is of course true for most team or combat sports, virtually all of them go a lot further by basing the result on some sort of point score, which says a lot more about the match than merely who won: A 6-0 win in association football is not the same as a 2-1 (the first being a "crush" and the second being a rather narrow win), and a 3-3 draw is not the same as a 0-0 one (the first one indicating a wild game, the second a tenacious one). Further in-game metrics such as "ball control" and "shots on goal" are often employed to paint a high-level picture for spectators.

Given that literally hundreds, if not thousands, of variants to chess rules exist, I should be surprised if no one has ever proposed an improvement to how chess is scored, but alas, I have not found any material on that subject. I'm looking for a new angle to see top-level matches from, where, when analyzing games, one often cannot help but feel that some are won by a larger margin than others, and similar insights.

Do any alternatives to ternary (win, draw, loss) chess scoring exist?

I think the only alternative would be in match play or comparing a player's score across multiple games against another player or players.

For example, in a 12 game match between two players:

(+3 =8 -1) would be worse than (+5 =6 -1)

even though the first player won both matches.

Scoring by material count or number of moves played would not be beneficial. If the number of moves mattered, with shorter games being considered crushing defeats, players would just refuse to resign and drag the game out. On the other hand, I can lose in two moves without losing any pieces.

The only thing that seems to make sense is to compare score across multiple games against an opponent or field of opponents. You may have a better comparison considering a GM's total score in a tournament with many rounds. In a 9 round tournament, a 9.0 score would be crushing the competition. Winning the tournament with 6.5 would be less of an accomplishment.


Seeking an explanation for Nezhmetidnov’s queen sacrifice In this game, Rashid Nezhmetidnov sacrificed his queen for a bishop. I see that White gets an outpost on d5, but I can't find anything else that justifises the sacrifice. Is there any other compensation that exists?
[Title "Rashid Gibiatovich Nezhmetdinov-Oleg L Chernikov, Chigorin Team Cup, Rostov-on-Don USSR, 1962"]
[FEN ""]
[startply "22"]

1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 g6 5. Nc3 Bg7 6. Be3 Nf6 7. Bc4 O-O 8. Bb3 Ng4 9. Qxg4 Nxd4 10. Qh4 Qa5 11. O-O Bf6 12. Qxf6 Ne2+ 13. Nxe2 exf6 14. Nc3 Re8 15. Nd5 Re6 16. Bd4 Kg7 17. Rad1 d6 18. Rd3 Bd7 19. Rf3 Bb5 20. Bc3 Qd8 21. Nxf6 Be2 22. Nxh7+ Kg8 23. Rh3 Re5 24. f4 Bxf1 25. Kxf1 Rc8 26. Bd4 b5 27. Ng5 Rc7 28. Bxf7+ Rxf7 29. Rh8+ Kxh8 30. Nxf7+ Kh7 31. Nxd8 Rxe4 32. Nc6 Rxf4+ 33. Ke2

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


How do I respond as Black to 1. e4 e6 2.e5? What is the best way to respond in the French Defense to 2. e5? It has to be wrong to play this way. I am of the opinion that d5 is a good answer. I can find no reference to this move in MCO.

Respond with 2... d5. If White plays 3. exd6, then 3.. Bd6. White has wasted 3 moves on the e-pawn, and after that Black has one piece developed against white's zero.
Normally White just follows 2... d5 with 3. d4 and we're back into the regular French Defence advanced variation.


Mate In N algorithm-Lichess Computer Analysis Is it possible to have the computer analysis report mate in 12 moves to only change that to mate in higher number of moves, like 15 for example, after it searches deeper?

It is possible, if the computer program has a bug... A position is assigned a win-in-(k+1) only when one move from that leads to a loss-in-k, and assigned a loss-in-k only when every move from that leads to a win-in-k or when k=0 and it is a checkmate. So every correct chess program will never assign a position to win-in-12 and then later revise it to win-in-15 due to "searching deeper". No heuristic pruning techniques should ever affect this, as heuristic pruning can only weaken the evaluation away from a win/loss (in a correct program).
However, it is possible that the program is designed to search deeper if the input position satisfies a certain criterion C, in which case it may find a win-in-12 for a given position X that satisfies C, but then one move later the resulting position Y no longer satisfies C and so the program does not search as deep lines as it did for X, and so fails to find a win-in-11 for Y! It may still be able to prove a win-in-15 for Y if it has some rudimentary endgame evaluation. For example, KQK is always a win-in-10, so we do not have to do any search to return win-in-10 in such a position. Thus the program might do a more shallow search for Y and see a KQK in the search tree and immediately return win-in-10, but a deeper search would have revealed that it was actually win-in-5. This can produce the observed effect, but is due to "searching less deep"!
Note that clicking on "go deeper" on Lichess analysis may not use the same memoization table that had been used before at the lower depth level. One clear example is here where the cached analysis states #−30 but if you click "go deeper" it clearly starts completely from scratch. This is expected; after all it makes no sense to store huge tables along with the cached analysis. I think that if you cannot provide an actual concrete example of the behaviour you are asking about, it is difficult to address your hypothetical question more than I already have.


Why did I lose on time with three pawns versus a knight? Shouldn't it be a draw? I just lost an online game on time (while playing on lichess.org). I had three pawns and my opponent had just a knight. I don't understand why it's not a draw. Shouldn't it be a draw because my opponent does not have enough material to checkmate me?

Draw with insufficient material is covered in article 9.6:

  The game is drawn when a position is reached from which a checkmate cannot occur by any possible series of legal moves, even with the most unskilled play.

With a given material, it is possible to construct a checkmate (assuming your cooperation or horrible blunders), so it is not a draw.


How to build a simplified Sicilian defence reperoire I have been playing chess practically all of my life but during phases, I would play a lot for a couple of months and then spend a whole year without playing.

Right now I am in one of those phases but I am determined to stick with it and really improve so I have been taking on tactics and end game studying but my Achilles heel has always been the opening theory.

I really like to play the Sicilian defense, in particular the Dragon and have a couple of books on it but there are so many different replies and variations after 1. ..., c5 that going this route seems like an impossible undertaking, I've even read somewhere about the "Sicilian Jungle", and I've had a few bad experiences when trying to force a Dragon-like structure without considering white's responses.

So my question is; considering white's most common responses to the first couple of moves, which variations are the ones the would be more beneficial to begin this training and that can help limit white's options?

Thank you.

Alas, the Sicilian is not an opening for the faint of heart. It strives to exploit the complexity and dynamic nature of the position, so it is quite hard to find shallow solutions. At risk of avoiding your question, I would say that it is best, if you want to avoid theory, to pick up a line more alike the open game. Still, I did my best to show a nice plan.

First, lets handle the move 2 anti-Sicilians (2. c3). In general, they are in fact designed to reduce complexity, so a small bit of knowledge can go a long way. Against 2. Nc3, you should continue with the move that you use against 2. Nf3. The closed Sicilian is a relatively complex opening still, but I find that up until 2000 USCF (or 1800 FIDE), Closed Sicilian players do not have a grasp of theory, so you can likely be safe to skim on that section of your study.

Against the Alapin Sicilian, the general recommendation is 2... Nf6. However, I think the line 2... e6 is underrated, so you may be able to use it to avoid theory. After all, particulars have to be studied individually. It is recommendable to find a personal line that is intuitive, but your general idea is to play d5.

For a generic solution against the open Sicilian 2. Nf3, you will want to avoid playing the Najdorf at least as every chess player and there grandmother has a way to play against it. Your try of using a Dragon-esque system was likely difficult as it is a highly theoretical variation and even then, semi-dubious. In addition, it seems troubling to play any line starting with 2... Nc6 due to the Rossolimo and the very sharp nature of the lines here.

My recommendation has to be the Kan variation (2... e6 3. d4 cxd4 4. Nxd4 a6). While it can be a bit difficult to learn, it is one of the less sharp lines and it is seldom studied by lower rated players. I would try playing around in some relatively short games and seeing where you falter. There is plenty of material on the specifics of the Kan variation, but the general idea is to play Nf6, d6, Be7, O-O, Nbd7, and Re8. This sort of "hedgehog" style position gives plenty of opportunity to both sides and should not require too much theoretical knowledge.

Good luck :)


Why is playing f4 here not correct? Yesterday I played a game chess whose link is: https://lichess.org/rnLeeqMD/white#30
The computer tells me that in the 16th move,when I played 16.f4, I made an inaccuracy.

My reasons for playing f4 are the next ones:

-if Black captures the pawn, the file f file will be open for the rook. Besides the d6 pawn will be become weak and susceptible to be attacked right away via Bf4 and Nb5.

-If Black does not capture the pawn, I can still exchange my pawn so the file gets open. However, in both cases, I allow my rook to go to f3 to later move to h3 where along with the other bishops it would exert comsiderable pressure on the kingside.

-My bishops amd Queen point to the kingisde so I think I should attack that part of the board. Maybe my white bishop square is not the best but it does not look probable that my e4 pawn can easily be exchanged or sacrificed so this bishop can effectively go to d3.

-Because Black’s knight has not moved yet I do not want to give any time to Black for them to make that move. So a move like f4 forces Black to move another thing.
Exactly for this, I am surprised that the computer suggests taking a slow course of action by preparing a rupture via a3-b4.

The other suggestions I am given such as playing f3 do not convince me much because although it protects the e pawn, it blocks the white bishop whoch already had a bad outlook on the square it is. Playing h3 is I think too slow although it prevents a junp from the knight to g4.

Could someone tell me what I got wrong in my analysis?

White has a big advantage in this position because of her space advantage and her bishop pair. All Black's minor pieces are very passive with no good square to aim for.

After 16.f4?! ef4 17.Bf4 Ne8 (or 17...Qe7, side-stepping any Nb5 attack), intending Nb8-d7-e5 White is still much better but Black has a great outpost on e5 for one of her knights, and the open h8-a1 diagonal for her bishop. Probably White will need to swap at least one piece, which is a minor but definite success for Black. Also, in the long run, the backward Pe4 may become blocked and weak.

If White cannot exploit the opening on the position with a direct thrust (such as Nb5 or e4-e5), she better refrains from 16.f4?! altogether.

On the other hand, a good constructive plan could be to prepare g2-g3 and f2-f4, intending to take back with Pg3 in case of ...ef4 : That way White would keep control on e5 and a dynamic pawn pair e4-f4 that will constantly threaten to advance further.


What is the most effective openings to beat a 2200-2400 rated computer at chess?(With White and Black) I have had good positions with the Hippopotamus opening with its Kings Indian structure(ranging up to +3 in evaluation) but in the end, the tactical superiority of the computer always gets in the way and I end up losing or drawing the game. The computer I am talking about is Computer Level 9 on Chess.com(Not to be confused with Komodo 8). My playing style is very tactical and aggressive, but I doubt that would work well against stronger Level 10. The openings that I am looking for are openings that are very positional in the beginning, but they also offer counterplay in the middlegame. Please suggest openings for white and black.

Wrong question.

If you want to beat a 2200-2400 opponent then you need to be a 2200-2400 level player.

The hippopotamus type openings are doomed to failure according to one old GM.  I find them very easy to beat but then  I do not usually play 2400 rated people.  OTOH they are not tactical type openings at all. Nor are they very aggressive.
If you want to play hardball tactics then play a more open type of opening.

You should master ONE basic opening and play that one.  It is not the opening that wins,  it is the player making the moves that wins or loses.

You should look at the French defense for black if you want to play that style.  For white try a Reti.  Or even just the Ruy.

A  Sicilian would be better but is much harder to learn.


What are some lines of the Queen's Gambit symmetrical variation for white? Some people who I play always play the symmetrical variation, and I don't know how to play it for white.

[fen ""]
1.d4 d5 2.c4 c5

It's really unknown, I've never seen it actually played except for maybe one or two internet blitz games out of ten thousand. But I've looked up some lines for you.

You play 3.cxd5 and now black needs to decide what to do.

The symmetrical 3...cxd4 4.Qxd4 followed by e4 just loses a pawn.

3...Qxd5 allows white to chase the queen, getting a lead in development:

[FEN ""]

1.d4 d5 2.c4 c5 3.cxd5 Qxd5 4.Nf3 cxd4 5.Nc3 Qa5 6.Nxd4

So black plays 3...Nf6. Now a thing like 4.Nf3 cxd4 5.Qxd4 Qxd5 stays completely symmetrical, but white can play 4.e4!.

Fundamental Chess Openings gives two lines, both a bit better for White because of better development:

[FEN ""]

1.d4 d5 2.c4 c5 3.cxd5 Nf6 4.e4 Nxe4 5.dxc5 Nxc5 6.Nf3 e6 7.Nc3 exd5 8.Qxd5

and

[FEN ""]

1.d4 d5 2.c4 c5 3.cxd5 Nf6 4.e4 Nxe4 5.dxc5 Qa5+ 6.Bd2 Nxd2 7.Qxd2 Qxc5 8.Na3


Why do they keep the scoresheet in classic chess? In the beginning I thought that players were keeping scoresheets for themselves, just in case of disagreement for claiming stuff like threefold repetition or  fifty-move rule or even just knowing the move number, but after watching a few tournaments I realised that it is something more official. It looks like it's mandatory to keep the scoresheet and in the end sign yours, along with the opponent's one.

So my question is why they should do that and what will happen if they are not going to write down the moves?

A scoresheet allows for a number of different things.

1. The scoresheet allows reconstruction of the game.

This is important for several reasons. Imagine that an earthquake occurs and upsets the board. (Or, more prosaically, the table was set up incorrectly and is upset by a light touch.) If there is no record, how would you reconstruct the position? Replaying a game simply because of an upset board is a tremendous waste of time, and it's far more mental strain than a player should be expected to handle.

Additionally, with modern storage and retrieval abilities, each game is seen as something to learn from. Every single recorded game is one that can teach us new things.

(Kriegspiel is an instance where it is vital to record the game for reconstruction. Most of the fun is in the post-game discussion, and it's impossible to do this without recording it.)

2. The scoresheet allows for arbitration of disputes.

Without a record, how would you go about proving to an official that 50 moves have occurred without a capture/pawn move? Without a record, how would you prove that your opponent is a scurrilous lout who secretly replaced his Queen on the board while you were in the restroom?

3. The scoresheet is an aid to players in reconstructing their play during the game.

Top chess players are able to remember large numbers of variations and lines. However, having the scoresheet available reduces one aspect of mental accounting: The player can always look at the scoresheet and mentally reproduce the game up to that point, rather than attempting to remember "now was it exd5?"

4. Signing the scoresheet is a way to ensure that both players accept the outcome of the game.

A player's signature is proof that they are satisfied with what happened. It indicates "yes, I played this match, and it happened this way. I agree that this record is accurate."

FIDE devotes section 8 of the Laws of Chess to the scoresheet. Note particularly that 8.7 states:

  At the conclusion of the game both players shall sign both scoresheets, indicating the result of the game. Even if incorrect, this result shall stand, unless the arbiter decides otherwise.


Was this Kramnik's mistake? [fen ""]
[title "A. Grischuk vs. V. Kramnik, FIDE Candidates 2018 (Mar 19, 2018)"]
[startply "140"]

1. c4 e6 2. Nc3 d5 3. d4 Nf6 4. Nf3 c5 5. e3 dxc4 6. Bxc4 a6 7. Bb3 b5 8. e4 cxd4 9. Nxd4 Bb7 10. e5 Ne4 11. O-O Nxc3 12. bxc3 Nc6 13. a4 Bc5 14. axb5 axb5 15. Rxa8 Bxa8 16. Nxb5 O-O 17. Qxd8 Rxd8 18. Bf4 h6 19. h4 Ne7 20. Rd1 Rb8 21. Bc4 Bc6 22. Nd4 Be4 23. h5 Nd5 24. Bxd5 Bxd5 25. Be3 Rc8 26. Re1 Bc4 27. Nf3 Ba3 28. Bd4 Bd3 29. Nd2 Bb2 30. Nf1 Rc4 31. Re3 Bf5 32. Ng3 Bh7 33. Kh2 Bc1 34. Re2 Bf4 35. Kh3 Ra4 36. Kg4 Bc1 37. Kf3 Bd3 38. Re1 Bb2 39. Ke3 Bc2 40. Kd2 Bb3 41. Rb1 Ra2 42. Kd3 Ba4 43. Ne4 Ba3 44. Ke3 Bc2 45. Re1 Bb3 46. g4 Bd5 47. Kd3 Be7 48. Rb1 Ra8 49. f4 Bh4 50. Rh1 Bd8 51. Rb1 Bc7 52. Ke3 Kh7 53. Nd6 Kg8 54. Rb5 Bc6 55. Rb4 Bd8 56. Bb6 Bh4 57. Bd4 Bg2 58. Rb2 Bc6 59. Rb6 Bg2 60. Rb2 Bc6 61. Rb3 Bg3 62. c4 Bh2 63. f5 exf5 64. Nxf5 Kh7 65. Bb2 Re8 66. Nd6 Re7 67. Rb8 f6 68. Rc8 Bh1 69. Nf5 Rb7 70. exf6 Rb3+ 71. Bc3 gxf6 72. Kd2 Bf4+ 73. Kc2 Rb8 74. Rxb8 Bxb8 75. Ne7 Be4+ 76. Kd2 Bf4+ 77. Ke2 Kg7 78. Nf5+ Kf7 79. Bd2 Be5 80. Bxh6 Ke6 81. Be3 Bxf5 82. gxf5+ Kxf5 83. h6 Kg6 84. c5 f5 85. Kf3 Kf7 86. Bf4 Bd4 87. c6 Ke7 88. c7 Kd7 89. h7 Kc8 90. Ke2 Kd7 91. Kd3 1-0

I'm looking at yesterday's game between Grischuk and Kramnik, and I'm trying to understand (disclaimer: I'm a weak recreational player) where did Grischuk make the difference. Is it right to say that Kramnik blundered on move 70? Or was the game lost earlier?

(Game from Chess.com)

I entered the position in ChessBase and got Komodo 9 to analyze it -- it says 70...Rb3+ was Black's best move by far, only giving White a +0.64 advantage (which means the engine thinks White is "64% of a pawn" better). The reason Rb3+ is a good move is that Black needs counterplay -- if he sits and does nothing, White will win easily (due to being up 2 pawns).

So, at that point the game was close to drawn, but White still had good chances to press and win (which he did).

Black's mistake was playing 76...Bf4+, giving White a winning advantage. Instead, he should have played 76...Bf3, attacking White's g4-pawn. Playing 76...Bf4+ allowed White to play 77. Ke2, stopping Black from playing Bf3.

It's important to note though that Kramnik's mistake isn't close to a blunder -- rather's it's a small inaccuracy that lost the game (at GM level this can happen). It's easy to analyze a game with an engine and criticize the play of even the top players in the world.

EDIT - I checked again on the engine, and Black should play 75...Bf3 instead of 75...Be4+ 76. Kd2 Bf3, since that just brings White's King one square closer.


How does Syzygy store its information? From reading everything I've found so far, I know that Syzygy uses both win/draw/loss files and distance-to-zero files, but I haven't found any information on the internal file format that these files use. I'm looking for the low level nitty gritty explanation.

Since there is no single comprehensive publication this is based on the probing code, the generator and various explanations from Ronald de Man (the author of the generator).

When probing pretty much any tablebase (aka huge compressed hash map):

The position is normalized ...
... mapped to an integer index.
The index is looked up in a table that identifies which "block" it belongs to.
The block is decompressed until the information for the index can be retrieved.

Then there usually is some code "outside" of probing, at least to resolve en passant captures.

Starting with the outside code for WDL. Syzygy tables use an optimization based on the following observation: If a position has a capture that achieves a particular value (e.g. is winning), then the position itself has at least that value (e.g. is winning). In this case the table can store an arbitrary lower value, whichever is best for compression, and this can be easily corrected by checking the subtables for captures.

To get a DTZ, a WDL probe needs to be done first. If the position is drawn, then DTZ is 0 and the table can store anything, whichever is best for compression. If the best move was a capture (which we can remember from the WDL probe), then the DTZ is +/-1 or +/-101 depending on the WDL, and the table can again store anything, whichever is best for compression.

Pawnful tables contain 4 subtables, one for each file of the "leading pawn" (after normalization).

WDL (sub)tables are two-sided, i.e. they essentially contain two seperate tables for each side of the endgame (unless the material is symmetric).

DTZ tables store only one side to move. So a brief 1-ply search may be required to compute the DTZ for the other side.

(1) About the normalization: There are multiple ways this could be done and it is not easy to tell in advance which one will lead to the best compression. The generator just tries different permutations. The final order of the pieces is stored in the header of the table file.

(2) Some combinatorics. The challenge is not to have large gaps for impossible positions. Although it is quite tricky, I don't think Syzygy does anything special here. Conceptually, pieces or groups of pieces are placed on the board in the order specified in the header.

(3) Compressed values are stored in blocks. The block size is specified in the table header. The table mapping indexes to blocks is sparse, so it allows jumping very close to the correct block and then requires a brief forward or backward scan to find the exact block. A block can store values for at most 65536 positions.

(4) Syzygy tables use custom compression based on RE-PAIR. An important feature is that it actually allows taking advantage of the opportunities to store arbitrary values that were identified above. Decompression is very fast and can stop as soon as the value for the desired index is available.

Optionally, DTZ tables can require another step f(wdl, stored value) = real value. This extra DTZ map is referenced in the table header and is itself a table with 8-bit entries. (Intrestingly this turned out to be insufficient for 7-piece endgames, even with pawns, so there is now another flag that enables 16-bit entries).

For DTZ values, if the generator determined that all values for a table are less than 100, precise half-move counts are not required to guarantee perfect play. Instead it sets a flag in the table header and rounds half-moves to full-moves to save space.

Also clearly there is no need to store the sign, or an additional offset of +/-100 for cursed endgames because this can be inferred from the WDL value.

Since decompression is very fast, there is no need for a cache. Instead engines can rely on the operating systems page cache to store (still compressed) blocks.

The 6 piece tables contain WDL and DTZ information for 3,787,154,440,416 unique positions in 150 Gigabytes, so ~0.3 bits per position.

All in all Syzygy tables improved upon previous tablebase formats in at least 3 of these areas, making it a very compact and fast format. Amazingly the generator is quite fast as well.

And of course using DTZ50 is a pragmatic choice, because this is just enough information to reliably make progress and allows perfect play (wrt. outcome) both with and without the 50-move rule. However based on the changes to Cfish that are published so far (RdM is now working on DTM tables), many of the techniques will apply to DTM as well.


Is it ethical to force a draw via perpetual check? I was playing this game. I was white. We reached a point where my opponent could checkmate me in one move (by moving Rook to C1) but I forced him to a draw by stating that I would constantly check him to all eternity using my two rooks.

He agreed to a draw but after a while it didn't feel right to me. I regretted forcing him to draw, I felt it was cheap of me to do so, and I think that he deserved a win.

So my question is: Is it ethical to force a draw like this one?

There is a rules in chess called Threefold repetition rule. This rule states that you can claim a draw if you are about to repeat the the position for a third time. This subsumes a situation called perpetual check which also leads to a draw.

So what you did in your game wasn't a case of extortion or abusing a flaw in the game - it was completely by the rules and everyday thousands of games are drawn in exactly that fashion.

PS: You also could have stopped the mating threat by playing Rc7, this would have given you a winning position as far as I can see. So by resigning you actually would have turned a winning position into a loss.


Why 2.d5 is much less common than other responses to the Mikenas Defense(1.d4 Nc6)? I recently came across 1.d4 Nc6 while playing a game and I was immediatly tempted to play 2.d5, and so I did it, then my opponent continued the game with Ne5.

After the game I went to an online database to check some reference on this opening, I saw it is called the Mikenas Defense, and to my surprise 2.Nf3 and 2.e4 are by far the most common responses to it, while 2.d5 occurs only in 5% of the games. I'm a ~1400 player and I'm still learning the basics of openings theory, I can understand that both of these moves help white to develop its pieces, but can't they be naturally developed after 2..Ne5(which seems to be the most played move after 2.d5) with something like 3.e4?

[fen ""]

1. d4 Nc6
2. d5 Ne5
3. e4

Just the opinion of a 2000 player.

[fen ""]

1. d4 Nc6 2. d5 Ne5 3. f4 Ng6 4. e4 e6

The idea of this opening, and others like the Alekhine and the Two Knights Tango, is to lure the white pawns forward to make them easier to attack.  Black gets a very cramped game, but it is playable.

[fen ""]

1. d4 Nc6 2. Nf3 d5 3. c4

The main purpose of Nf3 is to prevent black's knight from using that square.  After normal moves, black will find that blocking the c-pawn advance is considered bad.

One of the general objectives in openings is to control the center.  White can attack black's center with the c-pawn, yet black can't support this with his own pawn.  This leads to a small increase in white's advantage.


Chess Engine: Generate a Bitboard of Pinned Pieces I'm currently working on a chess engine and have a pseudo-legal move generator working. I'm looking for a way to efficiently generate a bitboard of pinned pieces, so I could skip them when generating legal moves. How would one go about doing this, given 12 bitboards for each piece, and a bitboard called UNSAFE with all the squares the opponent is threatening?

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.


Did Stein really ridicule Fischer for grabbing the poisoned pawn in the Najdorf Sicilian? I remember reading somewhere that Leonid Stein (one of the top players at that time) has ridiculed Bobby Fischer for grabbing the poisoned pawn in the Najdorf Sicilian during the Spassky-Fischer match in 1972. I wonder if that is really true. Perhaps it was a journalist's way of attracting readers' attention. Can anyone point me to a source of the citation?

Although it is hard to prove a negative, I don't believe that Stein ridiculed Fischer for taking the poisoned pawn. My evidence is:

An analysis on Chess.com of game 11 claims to source commentary of Stein's and others from Fischer-Spassky 1972 From a Soviet Point of View. Although I cannot find the original source, the commentary quoted on Chess.com is fair and balanced. In fact, 8...Qxb2 doesn't even receive a dubious mark
Googling leonid stein ridicule picks up no relevant articles on the first page
According to the Chessmaster database, Stein's co-comentators Bronstein and Korchnoi had grabbed the poisoned pawn before. I don't think that Stein would have been critical of a move that other top players had played before in a well analysed opening


How to offer a draw when the opponent is not present Imagine that your opponent is away from the board and you want to make a move and then offer a draw and leave for the toilet with some urgency. What is the solution to this inconvenience? Can a player rely on the arbiter to go to the trouble of hunting for the opponent and passing the draw offer?

The correct way of offering a draw is, as you probably know:

Make a move
Make an offer
Press the clock

When your opponent is not present:

Make a move
Stop the clock (or you can leave your time running)
Call an arbiter and say that you want to offer a draw, and your opponent isn't here
Start the opponent's time
You are free to go now - if you run into your opponent on the way, you can mention the offer
When you're back at the board, make your offer.

Note that the draw-offer is perfectly valid at any given time. The reason why you call an arbiter to explain the situation is to avoid being accused of distracting your opponent when you offer it in "incorrect" way.

Edit: Adding information from official FIDE rules:

  9.1.b.1: A player wishing to offer a draw shall do so after having made a move on the chessboard and before pressing his clock. An offer at any other time during play is still valid but Article 11.5 must be considered. No conditions can be attached to the offer. In both cases the offer cannot be withdrawn and remains valid until the opponent accepts it, rejects it orally, rejects it by touching a piece with the intention of moving or capturing it, or the game is concluded in some other way.

And

  11.5: It is forbidden to distract or annoy the opponent in any manner whatsoever. This includes unreasonable claims, unreasonable offers of a draw or the introduction of a source of noise into the playing area.


Open source engine that doesn't lose on time I'm looking for an open source engine (doesn't have to be very strong) that can be loaded with python chess uci module and can play at very fast time controls (few seconds plus tens of milliseconds of increment)

Thanks for your recommendations

Stockfish is strong and able to handle your time control increments. Have you tried Stockfish?