Historic time controls for World Championships According to the answer to this question we know that currently it is 100 minutes for 40 moves followed by an additional 50 minutes for 20 moves then an extra 15 minutes to finish the game with a 30 second increment from move 1 which works out at 3 minutes a move for the first 60 moves.
I remember from 20 years ago in the early days of digital clocks it was very similar. The one difference being that the players got 10 minutes to finish the game according to Bill Goichberg of the USCF.
Back in the day of analog clocks, when Fischer beat Spassky for the world title it was 40 moves in 150 minutes (no increment) plus 60 minutes for each 16 moves after that until the game was decided with adjournment with a sealed move after 5 hours play. So players were getting 3 minutes 45 seconds per move.
Back in Paul Morphy's day there were no time controls for world championship matches.
Can anyone fill in the gaps and identify when the time controls changed and to what?

I have spent far too much time on this as is, but here we go. Time control phase X/Y means X moves in Y minutes for each player, + means increment per moves (in seconds).
Steinitz's era
An idiosyncratic era with matches decided by direct negotiations.

1886: Steinitz-Zukertort, FT10 wins with 8-8 or 9-9 declared as draw

30/120 then 15/60

1889: Steinitz-Chigorin,?
1890: Steinitz-Gunsberg, FT10 wins with 8-8 or 9-9 declared as draw

26/210 then 15/60

1892: Steinitz-Chigorin, ?

Lasker's era
The time control for all of these is 15/60, except Lasker-Marshall 1907 and Lasker-Janowski 1910 which I couldn't find.

1894: Steinitz-Lasker, FT10 wins
1896: Lasker-Steinitz, FT10 wins
1907: Lasker-Marshall, FT8 wins
1908: Lasker-Tarrasch, FT8 wins
1910: Lasker-Schlechter, BO10
1910: Lasker-Janowski, FT8 wins
1921: Lasker-Capablanca, FT8 wins

Alekhine's era
Capablanca's "London Rules", subsequently adopted by Alekhine, made this fairly regular. Formats is first to 6 wins capped at 30 games, except the 1927 match which had no game limit. Time controls are 40/150.

1927: Capablanca-Alekhine
1929: Alekhine-Bogoljubov
1934: Bogoljubov-Alekhine
1935: Alekhine-Euwe
1937: Euwe-Alekhine

FIDE 1948
After the death of Alekhine, a quintuple round-robin with five of the best players in the world (Botvinnik, Smyslov, Keres, Reshevsky, Euwe). Botvinnik won. Games were 40/150 followed by 16/60.
FIDE era I
FIDE's championships were generally of a standard format, notwithstanding player disputes, leg-swinging, yoghurts and gurus, return matches and off-the-board politics.
All matches from Botvinnik-Bronstein 1951 to Kasparov-Karpov 1990 were 40/150 followed by 16/60.
All were also BO24 (champion retains title if 12-12), except the cancelled Fischer-Karpov 1975 (that was a point of contention in the negotiations), Karpov-Korchnoi 1978 and 1981, and the aborted Karpov-Kasparov 1984, which were all first to 6 wins.
A mess
Welcome to the era of FIDE and PCA and general chaos.
Direct matches (PCA/BrainGames/whatever really)

1993: Kasparov-Short, BO24, champion retains if 12-12

40/120 then 20/60 then adjournment

1995: Kasparov-Anand, BO20, champion retains if 10-10

40/120 then 20/60 then G/30

2000: Kasparov-Kramnik, BO16, champion retains if 8-8

? There is a time control at 40 moves but I can't find the details.

2004: Kramnik-Leko, BO14, champion retains if 7-7

?

Direct matches (FIDE)

1993: Karpov-Timman, BO24, tiebreaks if 12-12

40/150 then 16/60
Tiebreaks four sets of two games at 40/60 then 20/15

1996: Karpov-Kamsky, BO20, tiebreaks if 10-10

40/120 then 16/60 then adjournment

1998: Karpov-Anand, BO6, tiebreaks if 3-3

I can't find the details.

Knockout (FIDE)
Because FIDE had the brilliant idea to create a knockout format and further annoy the champions and challengers.

1999 (Khalifman), 2000 (Anand)

40/100 then 20/50 then G10+30
Tiebreaks G25+10 rapid, G15+10 blitz, Armageddon G5 vs G4 (+10 second increment?)

2002 (Ponomariov), 2004 (Kasimdzhanov)

40/75 then G15+30 (in 2004, 40/90 then G15+30)
Tiebreaks G20+10 rapid, G5+10 blitz (?), Armageddon G6 v G5

FIDE era 2
The reunification of the championship begins with an 8-player double round-robin in 2005.

2005 (Topalov)

40/120 then 20/60 then G15+30

Sanity ensues when Topalov wins in 2006, and from there everything becomes much nicer.

2006 to 2014: BO12, tiebreaks if 6-6

40/120 then 20/60 then G15+30
Tiebreaks 1 set of 4 games of G25+10, then 5 sets of 2 games of G5+3, then Armageddon G4 v G5 with +3 seconds increment from move 61 and above.

In 2016 the classical time control was tweaked slightly, but format and tiebreaks remained the same.

2016 and 2018: BO12, tiebreaks if 6-6

40/100+30 then 20/50+30 then G15+30
Tiebreaks see 2006-2014.

Sources
Wikipedia, chessgames.com, Edward Winter's history pages, Mark Week's WCC pages, 2005 FIDE regulations (Wayback Machine, .doc file), FIDE regulations (.pdf files) (2012, 2013, 2014, 2016, 2018, and a bunch of books and other pages I am not fully remembering now.)


What are the symptoms of a weak back rank? In the search for answers beyond immediately threatening back rank mates. How early is it possible to spot that you'll have problems down the aisle, from a strategic perspective? What are the defining characteristics of this position?

One of the most famous chess games ever. Both sides have back rank mates!

29...Qb2!! (0-1) wins the game for Black by back-rank mate

  http://www.chessgames.com/perl/chessgame?gid=1261680

None of the king-side pawns move
Both kings are behind the pawns and have no escape square
There are open-files on the board
Both side has a rook and a queen exploring the open files
No white rook on the back rank defending (the white rook is on the third rank)
The white queen is the only piece guarding the f1 square


What's the history behind stalemate not being a win? If your opponent eliminates all your options to move, you don't lose in chess, but is regarded an equal to your opponent. Isn't this peculiar? In most games and in real life hunt and war it is a winning strategy to eliminate the opponent's options to move. "Oh, you can't move now, can you, so it's obviously my turn again! (grinning)"

Is there some history to this? Stalemate does make chess much more interesting, but was it kind of invented in order to be so, or how could it have evolved? Is there some Victorian age gentlemanship involved here?

Wikipedia has a history of the stalemate rule. Stalemate being a draw seems to have become more popular in the 15th century, in part due to Lucena

  Lucena (c. 1497) treated stalemate as an inferior form of victory (Murray 1913:461), which in games played for money won only half the stake, and this continued to be the case in Spain as late as 1600 (Murray 1913:833).


How do you draw in an opposite color bishops endgame with two pawns down? Is it possible to draw in such an endgame? Are there exceptions? If so, what are they?

Yes, if the pawns can be blockaded it's often an easy draw. One example:

[fen "8/4k3/4P3/3P4/2B1K3/b7/8/8 w KQkq - 0 1"]

As long as the black bishop controls d6, the pawns aren't going anywhere.

But two pawns are two pawns. If they are farther apart and far progressed often one pawn wins the bishop and the other pawn wins the game, or one pawn sacrifices itself so the other one cannot be blocked by the bishop anymore. But this depends heavily on the specifics of the position.


Can a GM title be given to someone after he dies? Can a GM title be given to someone after he dies? For example can Rashid Nezhmetdinov receive a GM title for his contribution to Chess?

Yes, it is possible. FIDE can award the title of honorary grandmaster, based on a player's past performances and/or other contributions to chess.

Most of the honorary grandmasters were still alive when they were awarded the title. However, there are two examples where the title was awarded posthumously:
GM Rudolf Maric and GM Karoly Honfi.


What is the Universal Rating System (URS)? While watching this year's 2020 Champions Showdown Chess 9LX I noticed they gave players' ratings according to the URS or Universal Rating System. Which are the characteristics of this rating system?

The Universal Rating System is an alternate rating system which, according to the project's web site:

The Universal Rating System™ (URS™ for short), is a revolutionary new
sport’s rating system designed to assess the relative strength of
participants across a wide variety of competitor vs competitor sports
or games.
The URS™ was developed as the result of a collaborative research
project funded by the Grand Chess Tour, the Kasparov Chess Foundation
and the Chess Club and Scholastic Center of Saint Louis.

According to the project's FAQ page, the major differences between URS ratings and FIDE Elo ratings are:

There are many differences between the URS™ and the FIDE system. The
most striking difference is that the URS™ calculates only one rating
for each player, informed by their results at all rates of play. This
published rating is the URS™ system's assessment of each player's
strength at Classical chess (defined as a rate of play where each
player has at least 2 hours for their first 60 moves). The URS™
recognizes that there is useful information about a player's
over-the-board chess strength in all game results regardless of the
time limit, and can therefore more effectively estimate a player's
Classical chess strength by also considering their results at games
played at faster time controls. As the speed of play increases, the
URS™ assigns less and less importance to the game results relative to
games played at slower time controls.
Furthermore, the URS™ is a weighted performance rating, calculated
across several years of previous game results for all players. Older
games are given less importance than more recent games, by applying an
exponential decay rate. Unlike traditional performance ratings, which
are based upon the opponents' rating at the time the game was played,
the URS™ constantly reassesses the strength of all opponents and
searches for the most likely set of current ratings for all players,
in order to best explain the observed results.


Is there a name for the a position where King is on the first/last row and an enemy pawn is directly in front? I'm trying to figure out if there is any name for this particular position so that it might be easier for me to research it more - not so much the rook as much as having king behind the pawn. I play queenside castle a fair bit and find that if given the opportunity to get into this position it usually is beneficial.

[fen "1k1r4/pPp5/8/8/8/8/8/7K b - - 0 1"]

Here it is in one of my games from yesterday. (I'm sure there were better moves for probably both of us, this is just to better explain since the above kinda looks like endgame)

[FEN "1k1r3r/pPbn4/4p3/8/3Pp1B1/2q3pP/2P1Q1P1/R3K2R w KQ - 0 1"]
1.d4 e6 2.e3 d5 3.Nc3 Bd6 4.Nf3 Bd7 5.h3 Qe7 6.a3 Nf6 7.b4 Nc6 8.Be2 O-O-O 9.Bb2 h5 10.b5 Nb8 11.a4 Ne4 12.Nxe4 dxe4 13.Ne5 g5 14.Nxd7 Nxd7 15.a5 f5 16.b6 Kb8 17.bxc7+ Bxc7 18.a6 f4 19.Bc3 fxe3 20.fxe3 g4 21.axb7 g3 22.Bxh5 Qg5 23.Bg4 Qxe3+ 24.Qe2 Qxc3+ 0-1

There is no explicit name for this position, but it is known that the pawn can act as a line of defense for the king. Its presence can obstruct the other side from creating a path towards the king as the pawn cannot be easily targeted.


Will quantum computers solve chess? The theory is that there are more that 10^40 positions, and a computer that works with an atomic scale has to be impossibly large(As in galaxy-scale large), and well beyond our current level of knowledge.

But now, quantum computers will soon be available. This computer can have 2^n, instead of n bytes of space, because of quantum states. With this new large place for tablebases, will chess  be solved? Of course, this will take more breakthroughs in the future, but will we see 8 piece databases in the following years?

Many questions on the possibility of solving chess revolve on the fact that we don't have enough computer space to fill them. Will quantum computers change the status quo?

I'm not an expert on quantum computation but my understanding is that quantum computers are not expected to be useful for chess.

Quantum algorithms are very good at finding needles in haystacks: the three big quantum algorithms are Shor's factorization algorithm, Grover's database lookup algorithm and the Deutsch–Jozsa algorithm, which essentially determines whether a long list of numbers is either all zeroes, all ones or half of each.
All of these problems can be seen as examples of "I've hidden something: you must find it quickly." In factorization, I've "hidden" the prime factors and you must find them; in database lookup, I've hidden an entry with a given key in a large unsorted table and you must find it; in the problem solved by Deutsch–Jozsa, I might have placed a large number of zeroes in a table of ones but, with a classical algorithm, when you've looked at half the table and seen only ones, you might have just been unlucky and looked at the "wrong" half.  Note also that all of these problems could be solved quickly by an unrealistically parallel classical computer: you could try all the factors in parallel, look at all the database entries in parallel and look at all the values in the zero-one table in parallel.

Solving chess isn't even slightly like any of these problems. It's a fundamentally sequential activity. Whether or not my move is any good depends on what you do in response. Whether or not your response is any good depends on what I do in response to that. And so on.  You might imagine you can do the first ply of the search by taking a superposition of the possible moves.  But then what do you do at the second ply? You can't just take the superposition of all the positions we could be in after two ply because that has forgotten the tree structure. For example, consider this very artificial position, with white to move:

[FEN "1k6/ppp5/5Q2/7q/8/8/PPP5/1K6 w - - 0 2"]

If we forget the tree structure, Black is very happy. He says, "In two ply, the best position I can be in is that I deliver checkmate!"  This is true but, of course, White will never allow that, since White's best move is one that prevents Black from checkmating (or doing anything else).  Chess isn't about figuring out the best move you can possibly make in N ply: it's about figuring out the best move that your opponent will allow you to play in N ply. Quantum computers don't seem to be good at this back-and-forth, give-and-take reasoning. We don't even know how to solve chess with an unrealistically parallel classical computer.


Undermining pawn chains at the "wrong" end Usually if there is a blocked pawn chain one is trying to attack it close to its base with a pawn from the side.

For instance, in the classical king's Indian black is playing f5 (not c6) and later (if white plays f3) perhaps even g4 etc. White on the other hand is pushing c5 (not f4).

I am aware why attacking chains in this way is generally the best choice.

Are there any examples in openings or famous games (besides the French defence f7-f6) where the pawn chain is attacked at the other, "wrong" end?

The first example that springs to mind are the Benoni structures:

[FEN ""]

1. d4 Nf6 2. c4 c5 3. d5 (3. dxc5? e6 {Black recovers the pawn favourably, so we see that 2...c5 induces the d-pawn forwards to be challenged later.}) e6 {Black challenges the head of the pawn chain, rather than the base.} (3... b5 {Attacking the base of the pawn chain with the Benko gambit is also a popular try.})


How do chess engines evaluate a position if the position is in the middle of an exchange? In the minimax algorithm, chess engines do a depth-first search as far as they can calculate ahead, and then evaluate all these final positions. Then, using these evaluations they work backwards one move at a time and assign values to the previous positions. Eventually they reach the current, starting position and give it an evaluation value.

However, how would minimax chess engines evaluate a final position if it was in the middle of some exchange? For example, take the following:

e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Bxc6

Let's say an engine's depth capacity was 7 ply (a move from either player), and it reached this position as one of the final positions in its calculations from the start of the game. It wouldn't be able to calculate further (and see Black could play 4...dxc6) and would have to evaluate this position now. To me, it seems it would have to assign this final position a +3 advantage for White, but I know that chess engines have a way around this.

My question is, how do chess engines get around this scenario?

A good chess engine won't stop after a predetermined number of moves, but will keep looking until the position is "quiescent", which roughly speaking means that there are no pending captures or checks. See Quiescence Search in chessprogramming wikispaces for a more detailed explanation.


What defines a forcing move with major/minor pieces? I have been taking various training tests and the answer almost always involves some sort of forcing move.  Clearly attacking a king will always force a response but when another piece is involved (whether it be major or minor) an attack does not need to be forcing.  Are there rules of thumb to help identify forces in these cases?  I tend to look for mates, royal forks followed by forks and then winning exchanges.  Where I stumble is if a test involves a forcing attack that leads to mate.  I always just assume I would sacrifice the piece to stay alive.

Forcing move is a term for a move that leaves an opponent with a few options, only one of which does not lead to an immediate loss. This could refer to a variety of circumstances. For example, you might see a mate in 3 puzzle in which the first move is a forcing move because the opponent's only other legal move falls to a mate in 1. The term can also be used in opening theory, like in Ruy Lopez situations where black's b5 forces Bb3, or the loss of the bishop. The term may also be used for situations like 1.e4 c5 2. Nf3 Nc6 3. Bb5 a6, after which white is left with one good option, 4. Bxc6, and several bad options, such as 4. Ba4, which just loses the bishop, 4. Bc4, which allows black queenside expansion while losing another move, 4. Bd3, which blocks the d-pawn, 4. Be2 which is probably the best alternative but yields the b5 square without a fight, and 4. Bf1, which severely hampers development. While white has other options, they are strategically weak, and it could be said that black's a6 is a forcing move. So there is a wide spectrum between checkmate situations and less dramatic situations in which there is only one reasonable move.


What is a good plan for white against the Rubinstein variation in the French defense? I always play the Tarrasch variation against the French defense and I have quite some good results with it.

Nevertheless, when black exchanges on e4 and the game transposes into the Rubinstein variation, I have no good plan for white and don't know how to proceed. I also don't like the fast exchange on f6, which happens very often.

Can anyone give me a good plan for white?

Thanks in advance.

[fen ""]

1.e4 e6
2.d4 d5
3.Nd2 dxe4
4.Nxe4 Nd7
5.Nf3 Ngf6

INTRODUCTION:

You did not have to award a bounty, all you had to do is ask me to expand on my comment. I would have posted this answer.

To be honest, I thought that you found the line and solved your problem...

CONCRETE LINES:

Pay attention to the comments that go along with moves. You will see comments inside the textbox. Textbox is placed just below the PGN viewer (below the chess diagram ).

[Title "Kasparov's c3"]
[fen ""]

1.e4 e6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nd7 5.Nf3 Ngf6 6.Nxf6+ Nxf6 7.c3 {White has aggressive ideas in mind, in view of Qa4, and if Black plays …c7-c5, White can try to pose some concrete problems with moves like Ne5, Bb5, Qa4 as well as 0-0-0} c5 {If Black wants to fully equalize, he has to play this move} (7...Be7 {White can press here for an advantage} 8.Bd3 O-O 9.Qe2 b6 10.Bf4! Bb7 11.O-O-O) 8.Ne5 a6 {Black must play this} 9.Be3 Qc7 10.Qa4+ Nd7 11.Bb5 {Most critical continuation} (11.O-O-O {Black is fine here} cxd4 12.Nxd7 Bxd7 13.Qxd4 Bc6! {Black’s bishop is actively placed on c6 and he is ready to follow up with …Rd8}) cxd4 12.Bxd7+ Bxd7 13.Qxd4 {Now the idea to attack d7 one more time with 0-0-0 is a little awkward, so Black has to do something about this.} f6 (13...Bb5 14.a4 Bd6 15.Nxf7 Kxf7 16.axb5 axb5 {Black has to play precisely and still suffers in the resulting endgame positions. Rubinstein expert Georg Meier prefers this line, but I have more faith in f6, that is why I chose it as a main move for Black}) 14.Nxd7 Qxd7 15.Qxd7+ Kxd7 16.O-O-O Kc7! {Black has difficult position but has also great chances to equalize}

SUMMARY:

The move 7.c3 after 5.Nf3 Ngf6 6.Nxf6+ Nxf6 was popularized by Gary Kasparov, and is in fact one of the most critical tests of the Rubinstein Defense!

White clears the way to a4 for his queen, possibly followed by queenside castling and other aggressive moves such as Ne5 or Bb5.

In the critical line 7…c5! 8.Ne5 a6 9.Be3 Qc7 10.Qa4+ Nd7 11.Bb5 cxd4 12.Bxd7+ Bxd7 13.Qxd4, Black has a difficult choice to make.

Georg Meier has favored the structurally compromising 13…Bb5 14.a4 Bd6 15.Nxf7 Kxf7 16.axb5 axb5 and kind of worked it out to a draw.

Black is still suffering a bit here in practice, and that is why I prefer 13…f6 14.Nxd7 Qxd7 15.Qxd7 Kxd7, keeping the pawn-structure intact.

In both lines it is only White who can win, and Black has to play very precise in order to draw. From practical point of view, I believe this line is your best chance for playing for a win against Rubinstein French.

BOOK RECOMMENDATIONS:

I would get the French Defense The Solid Rubinstein Variation by Hannes Langrock, he did an excellent work in covering this line. It will help you grasp the ideas.

You might need additional resource to cover all the lines though... I think ECO C could be useful here...


I didn't notice that my opponent forgot to press the clock and made my move. What should I do? My opponent made a move but didn't press the clock. I didn't notice, so I made my move and then realised that the clock is already pressed. Am I allowed, under FIDE rules, to press the clock two times: first for my opponent and then for me?

According to the FIDE Laws of Chess:

6.2.2 A player must be allowed to stop his clock after making his move, even after the opponent has made his next move.

and

7.5.3 If the player presses the clock without making a move, it shall be considered and penalized as if an illegal move.

Together these mean that you would be wise to press your opponent's clock, press your clock and then tell your opponent that you have done so.
If you don't do so then 6.2.2 means that your opponent is entitled, after you move, to press the clock to complete their previous move. If you are not at the board then your clock can run while your opponent thinks.
7.5.3 means that you should tell your opponent so that they are aware and do not "remember" they forgot to press the clock and press it without making a move.


Python-chess is_zeroing and is_capture operation outputs I'm using python-chess to analyze a game.

I have my code like this, and I expect 3 boolean outputs.

print("is_castling: " + unicode(board.is_castling(node.move)));
print("is_zeroing: " + unicode(board.is_zeroing(node.move)));
print("is_capture: " + unicode(board.is_capture(node.move)));

But this is what I get.

is_castling: False
is_zeroing: 4194304
is_capture: 4194304

What am I missing here?

The code for those routines fairly liberally uses bitwise-and (&) rather than boolean-and (and) for the logical expressions, so I assume integer values rather than booleans are being returned. I would guess that you would see something similar with is_castling if castling is possible; the False value is returned explicitly rather than being the result of an expression evaluation.


How to use Stockfish to automatically analyze big DB of games I would like to have Stockfish (or another strong engine) automatically analyze a very large database of games (>1M games), so that the analysis is as strong as possible while making the best use of my computational resources. A naive approach would be to run Stockfish on every position in every game to a certain depth, and then report the evaluation. But this would waste CPU cycles on calculating trivial positions for way too long, for example positions in which a simple recapture is obviously the only not-losing move. How should I determine how long I should let the engine think in each position?

Run a shallow search (you might want to add multi-pv). Check the magnuitude of the lines if you want to re-run a proper search. Although this sounds weird, but this is a very common strategy in Stockfish (eg: move reductions). Your won't waste your previous search because the hash-table should speed up your next search. You can read more here.

For example, you wouldn't want to waste CPU cycles in a position where white is a rook ahead.

Otherwise, I don't see a non-trivial way to detect if a position is "interesting" to search.


Why don't people play the Englund Gambit? [FEN ""]

1. d4 e5

I have been playing this gambit for over 8 months with extensive analysis and have come to the conclusion that it is a very playable opening and, in many cases, black can achieve a position that gives him attacking chances. Why don't people play the Englund Gambit then?

A part of it has to be that white doesn't have to keep the pawn.
[FEN ""]
1. d4 e5 2. dxe5 Nc6 3. Nf3 Qe7 4. Nc3 Nxe5

4.Nc3 is actually the most popular move in lichess database. Black Queen is placed a bit strangely on e7, it is blocking the development of the dark-squared bishop and not supporting the d-pawn if it wants to move to d5. Black can double white pawns with Nxf3, but white has plenty of activity to compensate for it. White has many promising continuations, but here is one:
[FEN ""]
1. d4 e5 2. dxe5 Nc6 3. Nf3 Qe7 4. Nc3 Nxe5
5. Bf4 Nxf3+ 6. gxf3 Qb4 7. Qd2 d6 8. e4

This position is not exactly a gambiter's dream, since white is much more active, and also stockfish gives it 1.5.


Does playing chess with a real board help improvement more than play online? I read somewhere that playing and making moves otb is better than online for improvement. Is this true?

I play most (>95%) of my games online, and when I play with a real board, I find a bit difficult to translate positions I already played and the visual pattern matching of tactical situations takes longer. Not to look at the board then, helps a bit.
So, I think, when you prepare for a board tournament, or something like this, preparing on a real board will help. When you only play online all the time, it doesn't matter.


What is the best approach to this situation? So I am still learning chess and I have a lot of trouble in these situations. Please help me with what to do in the next few turns.

You are a queen and a piece down. Your position is completely hopeless. Your best move here is to resign the game.
It's not clear how well your opponent has played to reach this position but you have clearly played very badly indeed. An opponent who was good enough to reach this position is going to finish you off very quickly regardless of what you do.
As a beginner you need to start by learning about opening principles, tactics and simple endgames. If you use the search function in this forum you will find many questions and answers that can help you with these.


How many positions are there in n-pieces endgame tablebases for different values of n? Note that I don't want the exact values, I only need approximations. And I am only interested in small values of n (not more than 12).

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

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

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

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

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

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

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

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


Train Leela Chess against myself Is it possible to play against a "virgin" Leela Chess engine to see how many games it takes it to beat me? That is, can I train Leela Chess by playing against it myself?

Not an expert but you can play against a "virgin" Leela by using one of the younger nets. For example in the first Leela test (the so-called training run) the strongest net was 11248. If you play against, e.g., net 00010, it'll be much weaker.

However, you can't train Leela by playing against it. You can play against the trained product, but you can't train Leela yourself. That's because Leela is supposed to learn entirely by self-play (that's why its full name is Leela Chess Zero - "Zero" for zero human knowledge).


What does the chief arbiter do? The rules of chess are straightforward so I must ask what does the chief arbiter do? what is the difference between him and a regular arbiter?

For example Anand and Carlsen had to meet him behind closed doors before the world championship started.

The chief arbiter is in practice no different from a standard arbiter - it is more a convenience in tournament organization.

In many tournament there are so many players that it is necessary to have several arbiters, and of those usually the one with the highest title (often IA for professional or large tournaments) is considered the 'chief' arbiter who is responsible as arbiter for all purposes that concern FIDE, etc. and to whom all other arbiters report. This also allows for less experienced arbiters to be used where necessary, as disputes with a less experienced arbiter (unlikely, but possible) can then be taken to the chief arbiter.


Sicilian Scheveningen versus Najdorf: What are some of the characteristics that differentiate the two openings? I would like to compare the Sicilian Scheveningen

[FEN ""]
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e6

with the Sicilian Najdorf

[FEN ""]
1.e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6

Please note that I am only concerned about positions where the two openings share a common pawn structure; meaning Black has pawns on e6 and d6 and not on the positions in the Najdorf where Black has played an early ...e5. In the lines where these two openings share a common central pawn structure, what are some of the characteristics that differentiate the two openings regarding piece placement and Black's minority attack on the queenside with a7-a6 and b7-b5? I am mostly interested in contrasting different middlegame plans and tactics based on piece placement such as the knight at b8 going to either d7 (typical of Najdorf) or c6 (typical of the Scheveningen) as an example.

I just adore the Najdorf. So I cannot help favoring it over the Scheveningen. Yes, these two variations differ. They differ because white uses a bit different attacking strategies. The great thing about the Najdorf is that there are excellent ways of counter-attacking. Black does choose between e7-e6 and e7-e5 in the different lines. For example, here is a line where black chooses e7-e6

[FEN ""]
1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bc4 e6

I think that by looking at the main lines of each variation will answer your question in the best way. For Najdorf, I can say that the Nb8 usually goes to d7. Yet the exact placement of pieces and plans depends fully on the plan that white chooses. For example, white has the classical attack with Bg5, f4 and Qf3.

[FEN ""]
1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 h6 8.Bh4 Be7 9.Qf3 Qc7 10.O-O-O Nbd7

In general, the sharp variations lead to concrete positions, where the best options differ from position to position. If white chooses to be aggressive in either of the two variations (Scheveningen or Najdorf), you will get sharp and dynamic positions where a single error will be fatal. If white chooses more calm paths, I think the two variations are very similar in their piece placements and typical ideas (e.g. the exchange sacrifice Rc8xNc3). My advice is to get a solid overview of all the lines in the two variations and go through at least ten grandmaster games for every line.


Is there a better winning plan from move 37? From move 37-43 my plan was to convince my opponent to open the position for me with f4.  This worked.  If they did not oblige then I was going to walk my king to c7 to free up my rook from defense of the b-pawn and start pushing kingside pawns.

Often I feel that winning is natural and I only have questions about games I lose.  Here I kept feeling there may be simpler plan that I didn't find. Can you suggest alternate plans?

Happy to receive feedback on any part of the game.

[White "NN"]
[Black "Michael West"]
[Result "0-1"]
[ECO "B07"]
[FEN ""]

1.e4 g6 2.d4 Bg7 3.Nc3 d6 4.Be3 a6 5.a4 Nf6 6.h3 O-O 7.Nf3 Nc6 8.Qd2 e5 9.d5 Ne7 10.Be2 Bd7
11.a5 c6 12.Bb6 Qb8 13.O-O c5 14.Rab1 Nc8 15.Rfe1 Nxb6 16.axb6 a5 17.Qe3 Qd8 18.Nb5 Qxb6
19.c4 Bxb5 20.cxb5 Qd8 21.Bc4 Nh5 22.g3 b6 23.Kg2 Ra7 24.b3 Qe7 25.Re2 Re8 26.Ne1 Qf8
27.Nd3 f6 28.Rf1 Bh6 29.Qf3 Rf7 30.Nb2 Ng7 31.Na4 Rb8 32.Qd3 f5 33.f3 fxe4 34.Qxe4 Nf5
35.Ref2 Ne3+ 36.Kh2 Nxf1+ 37.Rxf1 Qe7 38.Kg2 Kf8 39.Nc3 Bd2 40.Nd1 Ra8 41.Nb2 Qg5 42.Kh2 Rb8
43.Na4 Ke7 44.f4 Qf5 45.Qe2 Bb4 46.fxe5 Qxf1 47.exd6+ Kd8 48.Qxf1 Rxf1 49.Bxf1 Kd7
50.Kg2 Kxd6 51.Bc4 Bd2 52.Kf3 Bg5 53.Nc3 Rf8+ 54.Ke2 Ke5 55.Na4 Rf6 56.Nb2 Kd4
57.Nd3 a4 58.Ne1 Kc3 59.Nf3 Rxf3 60.Kxf3 a3 61.b4 Kxc4 62.bxc5 Kxc5 63.Ke4 a2
64.Ke5 a1=Q+ 65.Ke6 Qf6+ 66.Kd7 Qd8+ 67.Ke6 Qe7# 0-1

I annotated the whole game, and a few things stuck out.

The first is a lesson for all players, and that is in this game, white was supposed to be playing on the queenside, and black had play on the kingside. White allowed the play on the queenside to be blocked, and thus had to just wait for the axe to fall on the other side of the board. You can never let the side where your play is to become blocked. The only exception is when you have a good piece sacrifice that you see coming to break up the locked pawns.

The second is that you really should have had a better feel for f5 in that position. It was screaming to be played, and had white not locked the queenside, your play may have been too slow. I do not know that you would not have played it differently, but f5 was screaming to be played.

Lastly, and this is probably something that you have seen in print before, and that is I think that maybe you cashed in a little too early taking the exchange. Sure, it was winning, but I might have just kept up the pressure for a while longer. In the line that I give to move 38, which plays out the plan below, but with stronger moves for white (in particular, repositioning the N to the kingside, and then to e4), you can see that while winning, it is still a bit of a tough nut to crack. Had you kept that strong knight and that passive Rf1, something easier might have popped up since defending that would not be fun.

As far as plans go after taking the exchange, I definitely would have looked at bishop moves that kept that knight on a4, like Be4-d4 if given the opportunity, and moved the king to c7 defending everything over there. You might have had to put a rook on e7 first to stop f4 in some cases. Then move all the major pieces to the kingside, and work on opening it up.

There are very extensive written notes in the lines below.

 [FEN ""]

 1. e4 g6 2. d4 Bg7 3. Nc3 d6 4. Be3 a6 5. a4 Nf6 6. h3 O-O 7. Nf3 Nc6 8. Qd2 e5 9. d5 Ne7 10. Be2 Bd7 11. a5 c6 (11... Nh5 $5 {This seems more in line with the spirit of the black's kingside play.} 12. g4 Nf4 13. Bxf4 exf4 14. Qxf4 Rb8 $1 {Only now that the Bg7 exerts incredible influence over the white queenside is this opening over there justified.} 15. Qd2 b5 16. axb6 Rxb6 17. Ra2 f5 $1 $11 {With play all over the board.}) 12. Bb6 Qb8 (12... Qe8 {This is very in the spirit of a fianchetto defense, and is often seen in the King's Indian. From e8, the queen will defend the Nh5 after Nh5 and f5.} 13. dxc6 $2 Bxc6 {And there is no time to win d6.}) 13. O-O (13. b4 $2 cxd5 14. exd5 e4 $19) 13... c5 14. Rab1 $2 {A mistake, but already in a tough position after letting the Bb6 get shut in.} (14. Ra3 $1 Nc8 15. Rb3) 14... Nc8 15. Rfe1 $2 {As often happens, one mistake follows another.} (15. Qe3 Nxb6 16. axb6 Qd8 17. Nd2 Qxb6 18. b4 {With good counterplay.}) 15... Nxb6 16. axb6 a5 {I do not understand this. First, not going after the free pawn, and second, it gives up the b5 square for no reason.} 17. Qe3 Qd8 18. Nb5 $2 (18. Nd2 {Seems much more natural.}) 18... Qxb6 19. c4 Bxb5 20. cxb5 Qd8 $1 $19 {This is now already positionally won for black beyond just the pawn. black can always seal the queenside, and continue the attack on the kingside where white has nothing to do but wait for the execution. The only plan for white might be if black gets careless, and allows a timely b4, but as long as black is careful, b4 axb4 is just the loss of a second pawn.} 21. Bc4 Nh5 22. g3 b6 {There is no real need for this yet. Bring the Qd8 out, and prepare f5.} 23. Kg2 Ra7 24. b3 Qe7 $2 {This does not spoil things, but you want the rooks on the f-file, or maybe g-file, and this puts the queen in the way.} (24... f5 {Or Kh8 first.} 25. exf5 gxf5 {And that the computer wants to trade queens here for white is a very good sign for you. You have a killer bishop compared to the pathetic piece on c4, an extra pawn, and most of white's pawns are weak.} 26. Qg5 Qxg5 27. Nxg5 Kh8 28. Ne6 Rg8 {As good as this bishop is, you do should not mind leaving just that Nh5 versus that Bc4.} 29. Nxg7 $2 Raxg7 {And Nf6, and h5 winning.}) 25. Re2 Re8 $2 {The clear plan is f5 soon, so why does the rook move from the potential open file? I see your plan with Qf8 and Bh6, which is admirable, but after f5, and the almost forced ef gf, the Bg7 will come to life and get to d4 soon. See my recent question about the "Gufeld Bishop", and if it gets to d4, it will be a knockout.} 26. Ne1 Qf8 27. Nd3 f6 (27... f5 {Again, is almost winning.}) 28. Rf1 Bh6 29. Qf3 Rf7 30. Nb2 Ng7 31. Na4 Rb8 32. Qd3 f5 33. f3 fxe4 {This does not feel right giving up the e4 square. I would have looked for a more patient move that gradually built up the attack on the kingside.} (33... Nh5 $1 {Bringing the N back into play with tempo. The threat is Bf4 winning.} 34. Qd1 Qe7 {Idea Qg5 with ominous threats.}) 34. Qxe4 Nf5 35. Ref2 Ne3+ (35... Be3 $1 36. Re2 Bd4 {And the troublesome knight is stuck. Now, you can bring your king to c7, and have what is almost an extra minor piece on the kingside.}) 36. Kh2 Nxf1+ $6 {Cashing in too early in my opinion. Your position is so strong, that an exchange is not enough.} 37. Rxf1 Qe7 38. Kg2 (38. Nb2 Kf8 39. Kg2 Ke8 40. h4 Kd7 41. Nd1 Kc7 42. Nf2 Rbf8 43. Nh3 (43. Ng4 Bf4 $1 $19 44. gxf4 Rxf4 45. Qe1 e4 46. Nh2 Rxh4 {And wins easily.}) 43... Qf6 (43... Qd7 44. Be2 Qf5 45. Nf2 Qxe4 46. Nxe4 Be3 47. Rd1 h6 48. Rd3 Bd4 49. Rd2 Rg7 50. Rd3 g5 51. h5 {And you still need to break through.}) 44. Bd3 Bd2 45. Rd1 {And it is still hard to breakthrough.}) 38... Kf8 39. Nc3 Bd2 (39... Qg5 40. Rf2 Qe3 41. Qxe3 Bxe3 42. Re2 Bd4 43. Ne4 Ke7 44. h4 Ra8 45. Ng5 Rg7 46. Ne6 Rgg8 47. Ra2 {And white is still hanging on by a thread.}) 40. Nd1 Ra8 41. Nb2 Qg5 42. Kh2 Rb8 (42... Bc3 $1 {Idea Bd4 so if the Na4 moves, you can trade it off leaving an extra piece to attack the kingside.} 43. Na4 (43. Nd3 a4 $19) 43... Bd4) 43. Na4 Ke7 (43...Be3 {Again, this plan.}) 44. f4 $2 {This makes it easy for black,and is the final mistake. Here, it was white, who lost patience.} Qf5 45. Qe2 Bb4 {And this is now out of play really.} 46. fxe5 Qxf1 47. exd6+ Kd8 48. Qxf1 Rxf1 49. Bxf1 Kd7 50. Kg2 Kxd6 51. Bc4 Bd2 52. Kf3 Bg5 53. Nc3 Rf8+ 54. Ke2 Ke5 55. Na4 Rf6 56. Nb2 Kd4 57. Nd3 a4 58. Ne1 Kc3 59. Nf3 Rxf3 60. Kxf3 a3 61. b4 Kxc4 62. bxc5 Kxc5 63. Ke4 a2 64. Ke5 a1=Q+ 65. Ke6 Qf6+ 66. Kd7 Qd8+ 67. Ke6 Qe7#


How to prepare for a rapid tournament How can I prepare for a rapid chess tournament (not chess sites tournament!)? For example, in one and half months, I am going to play a 15+5 tournament. I tried to find some rapid strategy or some advice on opening or middlegame whether I should play positional or tactical or attacking. However, I couldn't find anything. Could you give me some advice or strategy for 15+5 time control?

The best thing to do is play some games with that specific time control so you can get used to the pace.

Whether to play positional or tactical is a decision around your skills and what you know about your opponents play.  Though it is considered more difficult to defend than attack and that can lead your opponent to use more time.  It is also true that finding a plan is time consuming; so I would just play toward your skills.   Certainly you should study a lot of tactics so you can calculate quickly.

In general, you don't want to fall behind on the clock.  But you shouldn't panic if you do.  And don't play on your opponents time pressure.   5 second increment is a lot.  You should get comfortable defending "drawn" endgames where you can make a move within 5 seconds.

Semi-dubious openings like the Smith-Morra Gambit are common in quick tournaments.  Prepare your openings so your opponents don't get to have any such fun!


Is a Finite State Machine a good way to model chess? A very common model in programming is the Finite State Machine (FSM) (see here for a great worked example.)
Is a FSM a good way to model chess? What are the best ways to go about it? What chess features can be put in; what should be left out?

I have no big knowledge of computer science or engineering, or even chess programming, so I was wondering about this question.

Yes, I think so.

You'd have all possible board positions as states (so lots of states, but finite).
The starting position as an initial state. Legal moves as links between the states (so the "alphabet" would consist of all possible moves). Positions that end the game like checkmate, stalemate and dead positions as accepting states.

In the end you'd get the set of all possible chess games as the language that is accepted by the machine.

How you'd work this out formally with things like illegal moves, the 50- and 75- move rules, describing a list of legal moves formally et cetera are left as exercises for the reader.

Draw offers, and games ending in other external ways like a mobile phone going off should probably be left out.


OSX implementation of WinBoard / XBoard? Is there a Mac OSX implementation (or equivalent) of WinBoard / XBoard?

You can technically still use XBoard, but you will need to install X11 from MacPorts, since IIRC Apple no longer ships it.
Julien Marcel has a collection of well-compiled OS X chess engines (which do not require emulation).
As for not having a ChessBase client, HIARCS Chess Explorer does fine.
(FWIW, there is a port of XBoard to Cocoa - currently named OSXBoard - but it seems to have stalled.)


What if White declines the Volga Gambit? rnbq1rk1/p3ppbp/3p1np1/1ppP4/2P2B2/2N2N1P/PP2PPP1/R2QKB1R b KQ - 0 8

In the above position, Black gets a solid initiative and easy play on the weak White queenside pawns after 1.cxb5 (1. Nxb5? Ne4!).

But White can decline with 1.e3, intending 2.Be2, 3.O-O. Should Black respond with 1...Nbd7, waiting for White to take the pawn?

The position you've shown looks at first glance to be a poor side-line of the Benko (Volga) gambit for white, both the timing of h3 and Nc3 seem out of place. For instance let's reach that position (somewhat sensibly) by the following line: (annotated)

 [title "A path to OP's Benko gambit sideline"]
 [fen ""]
 1.d4 Nf6 2.c4 c5 3.d5 b5 4.Nf3 g6 5.Bf4 Bg7 6.h3 {h3 is well unnecessary here, in Benko the c8 bishop doesn't target the g4 square anyway, and if the f6 knight wants to re-route to e5 it doesn't have to go via g4, but d7. Thus, h3 is a waste of a tempo when white is already behind in development} (6.Nbd2 O-O 7.e4 {is much more to the point if you don't want to accept the gambit}) (6.e3 {yet another possibility, Nbd2 Be2 O-O are in queue unless black does something active} d6 {black cannot allow d6}) d6 7.Nc3 O-O 8.e3 {this is your suggestion: it doesn't really work here as you c3 knight is misplaced if you don't want to accept the gambit, now b4 comes with a tempo and your knight will end up either on the rim or hindering your own pieces} (8.Nxb5 {seems to be the most sensible choice, not damaging your pawn structure and not offering black to play a6 getting rid of its weak pawn and activating the bishop via a6-f1 diagonal.} Ne4 9.Nd2 {Not giving black chance to take on b2} Qa5 {pinning the knight and preventing Nc3 and preparing to take on b2 again} 10.Qc2 {sure visually it doesn't look great for white, but we're holding for the moment.}) (8.cxb5 a6 {accepts the gambit again but allows for the usual follow-up with a6-bxa6-Qb6 etc}) b4 {when the knight is on d2, b4 is less dangerous because you'll still be able to challenge it with a3 in time} 9.Ne2 Ne4 {g7 bishop alone is dominating the position, white lacks in development and dark square control, without any real other compensation to speak of} 10.Nd2 Nxd2 11.Qxd2 a5 {I think at this point black's advantage is quite clear.}

To conclude the above analysis in short key takeaways:

This is generally not a desirable Benko line for white. 6.h3 seems well out of place, white should be pushing to complete development (so that you can quickly start challenging black's queen-side or creating play in the center, none of which is possible with your king still on e1.)
7.Nc3 is not the way to go if you don't want to accept the gambit, you're allowing b4 without any repercussions for black, and your knight will be mis-placed. 7.Nbd2 is a much better try. If you want to stick to 7.Nc3 then it's best to start considering accepting the gambit, either 8.Nxb5 or 8.cxb5 each with their own merit and far more playable than 8.e3.
After 8.e3 b4 white is objectively behind: the knights seem out of coordination, the bishop on f4 is staring at a wall, there are no clear pawn breaks for white, the queen-side is permanently weak and there are no quick ways of creating counter-play on the king-side as we're far behind in any attempt to challenge the g7 bishop (Qd2-Bf4 battery is not possible with e3, nor is there any re-routing for the bishop to return to d4-g7 diagonal). This also answers your main question: Black should not respond by Nbd7 after 8.e3, instead 8...b4 is the main move to consider, exploiting the mis-placed c3 knight while increasing your grip on the dark squares, leaving no real ways for white to challenge the g7 bishop (note b4 is also stopping any future attempts at Bd2-Bc3)
Small recommendation (for the white side): avoid the Bf4 side-lines, none of them are really interesting for white, in fact in many of the Benko variations the bishop belongs to its original c1 square for a long time as b2 is continuously under pressure. Instead consider the 5.Qc2 variation if you don't want to accept the gambit, which can roughly go as follows: 5.Qc2 Bg7 6.e4 d6 7.Be2 O-O 8.O-O. I think after going through some of the possible side-lines of this variation, you can convince yourself that this is a much more sound continuation for white. Alternatively, accepting the gambit is known to yield the best play for white, namely lines such as 5.cxb5 a6 6.bxa6 Bxa6 7.Nc3 (black does have a different kind of compensation now, but by accepting the gambit we've prevented b4 altogether and revived chances to challenge the dark-squares) 7...Bg7 and many ways for white to continue.

Welcome to ask additional questions, either regarding the analysis or more related to the black side of the Benko gambit.


What alternatives are there to Chess Position Trainer? CPT is software for testing (among other things) one's opening repertoire knowledge.

I'm wondering if there are any other similar pieces of software I should consider.

I like the online chesstempo beta opening manager and trainer.
I have read on the facebook page of chess position trainer, that chess position trainer 6 is coming this year. I aspect a lot from this software.

Lucas Chess has some interesting repertoire making functions. Like importing best moves or all best moves from a bin book, for one collar. You can export the openings to pgn but I have noticed that there is an error and there are many threefold and more-fold repetitions in the games. You can solve this by importing the pgn in chess position trainer and export to pgn again. I also like Hiarcs Chess explorer. You can sort games for one player by opening name. So you can make repertoires for it. You can edit the player name in a text editor or in Chess Assistant.


Can someone explain this endgame puzzleto me with words? I came across this puzzle today: white to play and win.

For those who don't know this, it's a drill from chess.com: you have to play against the computer and win this.

The thing is, I really have no clue of what I should be aiming for. Even when following a computer's recommendations, I don't understand the solution.

Do you think this position can be explained with words or concepts? If so I'd love to hear about it.

8/5pk1/6p1/8/2K2PP1/8/8/8 w - - 0 1

To solve this you need to ask yourself 2 questions:

1) How could the position change so that Black can draw? White must try and avoid this.

2) How could the position change so that Black can no longer protect his pawn(s)?

1) Suppose White just pushes g5. Then Black can never be forced away from the defence of f7. Either the white king will move between e7 and e8 when the black king can just move between g7 and g8 (opposition doesn't matter) or white king will come to f6 when the black king can just oscillate between g8 and f8 and white can make no progress. White must avoid this.

Also if the f pawns end up on f7 (black) and f6 (white) and black can stop white's king getting to e7 then white will not be able to make progress. For example white king on d6 black king on e8 black to move plays Kd8 taking the opposition preventing white progress. On this side black has the space to always keep the opposition. White must also avoid this.

2) If white can achieve a position with the f pawn ahead of the g pawn with the king advanced to the e file one square ahead of the f pawn then black can be continuously zugzwanged into undefending his back pawn and white will win. This is because the white f pawn takes away a square from the black king and stops it triangulating when the white king triangulates.

The same applies if the g pawns come off, the f pawns are locked and the white king reaches the same position.

Another possibility is if the white king can reach the eighth rank and get behind the black pawns because his pawns will be more advanced.

So, the way to start is with Kd5. The aim is to get the king to e7 and then push the f pawn to try and get it to f6.

If black responds with Kf6 then after Kd6 from white black is in zugzwang and we get in Ke7 next move. Then white just pushes the f pawn up to f6.

If black responds with Kf8 or Kg8 then white plays Kd6 and if black keeps his king on f8 and e8 keeping the white king out of e7 then white pushes the f pawn. If black exchanges then white can push up to f7 when black will be zugzwanged into allowing Ke7 when white will win. If black pushes his pawn to g5 then white must not push f6 immediately or black will gain the opposition and it will be a draw. Instead white should outflank the black king with Kc7 aiming for Kc8. Then white can gain the opposition and play f6 if black defends the eighth rank with Ke8. If black abandons the eighth rank with Kd6 then white moves along the eighth rank and takes the f pawn winning.

A cunning ploy by black would be to reply to Kd5 with Kh6 with the aim of f5 if white continues on with Kd6. Then either white swaps pawns and black gets the opposition or white pushes g5+ and black comes round the back with Kh5 and they take each others' back pawn and it is a draw. White must instead reply to Kh6 with Ke5. Then black must play Kg7 to stop the white king coming in to f6. Now white plays Kd6 and we are back to plan A.

So, the problem relies very heavily on zugzwanging black in positions where the advanced white f pawn takes away a key square from the black king and also the idea that once the white f pawn is advanced if black abandons the eighth rank then white takes it and wins the black f pawn and will queen well before black.


Pawn Sacrifice Justification A few weeks ago, Magnus Carlsen (White) played against Anish Giri (Black), and this position was reached on the board on move 17 after black had played exf4:

Here is the full game:

[White "Magnus Carlsen"]
[Black "Anish Giri"]
[FEN ""]

1. c4 e5 2. Nc3 Nf6 3. Nf3 Nc6 4. g3 d5 5. cxd5 Nxd5 6. Bg2 Bc5 7. O-O O-O 8. d3 h6 9. Nxd5 Qxd5 10. a3 a5 11. Bd2 Qe612. Rc1 Qe7 13. Bc3 Nd4 14. e3 Nxf3+ 15. Qxf3 Bd6 16. Qh5 c617. f4 exf4 18. gxf4 Qxe3+ 19. Kh1 Rd8 20. Rce1 Qc5 21. f5 Bf822. Be4 Rd5 23. Rf3 b5 24. Rg1 Ra7 25. Bf6 g6 26. Qh3 Rd6 27. Qh4 Rxf6 28. Qxf6 Be7 29. Qxc6 Qxc6 30. Bxc6 Kg7 31. fxg6 fxg6 32. d4 a4 33. d5 b4 34. Be8 Bg5 35. h4 Bxh4 36. Rxg6+ Kh7 37. Rc6 Bg4 38. Rf4 Rg7 1-0

Now, with white to play, it would be natural would be to play exf4. However, gxf4 was played, hanging a pawn and letting black capture it with a check.

Can someone explain what is the logic behind such apparently wrong move?

As was stated in the answer to this post made by D M, one idea of capturing in this manner is to open up the g-file for white's rooks to attack black's king. In the game this proved to be a very potent idea, and in general it's a good idea to open up lines for one's rooks against the enemy king if one intends to attack it.

But there is another point to letting the e-pawn hang and that is to gain some tempi for the attack. When black's queen spends one tempo on capturing on e3 with check, white responds by playing Kh1 (a move that white wants to make in order to clear the g-file for the rooks), so while black used a tempo to make a move that does nothing to bolster their defenses, white made a move that is crucial for the coming attack (gaining 1 tempo, relatively speaking). Next white improves the position of the rook on c1 by going to e1. Once again, this is done with a gain of tempo, since black's queen is exposed on e3 and needs to spend one tempo moving away. This way white manages to get two "free" tempi to make his position more ready for going on the attack while black had to strut around with their queen, arguably doing nothing to bolster their defenses.

So the pawn sacrifice had a two-fold purpose here, I would say. First, by capturing with the g-pawn white opens up an important line of attack against black's king. Secondly, by investing the e-pawn white gains some free tempi to use in order to make their position more ready to go on the offensive against black's king.

In general, material count is only one of many factors in evaluating a position, and while it may be the most obvious it is not always the most important one. In this example, Carlsen judged that his superior piece coordination and black's kingside weaknesses were more important positional factors than the material count, and seeing how the game went it is difficult to argue that his judgement was off.


Do GPL-licensed engines permit modifying and closing the source code? Is it legal to modify and redistribute a GPL engine, under a more restrictive license (for example closing the source code)?

GPL-licensed software cannot become closed software. If you 'fork' it, then the rights on this fork remain the same (see GNU General Public License on Wikipedia).


Is Behting Study Still Beating Computers? This is the famous Behting study, first published in the magazine Bohemia in 1906, which is often used as a demonstration that computers can’t solve all positions.
White to move and draw with a very elegant move.
Spoiler:

 1. Kc6!! g1=Q 2. Nxh4 Qh1+ 3. Nhf3

Question is, is this study still beating engines?
Clarification: Suggesting best move, doesn't mean engine understands(or finds) the solution. Without evaluating it 0.00 or =/=, it doesn't mean it's solved. Actually, best move with -4.** means engine believes that best possible continuation for White is this move, with winning advantage for Black.
Imagine you ask a question to someone about a chess position in which White has a move which is the best and draws. You ask, which move is the best and why, and you get an answer like this: "Best chance is this move, but even if it's White's best chance, it looks losing". And you know that move draws. Would you accept this answer as correct answer? Definitely no.
I recommend to read:

A very instructive article about interpreting evaluations of chess engines: How to Read Engine Evaluations?
This post: Computer evaluations: How trustworthy are they?

Notes about edits: As the question turned into a discussion about whether the position solved by engines or not, I revised the question accordingly.
This question is totally about facts, and not opinion based. Some of the answers are opinion-based, but it's not the problem of the question. It's terribly wrong to close this question, instead of letting people discuss it.

For the record, the soundness of the Behting study has been under a cloud for some time because it is not easy to refute 1 Ng7+ Kg5 2 Nf3+ Kg4 3 Kf5 h3 4 Ke4 g1Q 5 Nxh6+ Kh5 6 Nxg1 h2 7 Nf3 h1Q 8 Nf5 "etc.", but according to recent analysis by GM John Nunn (2012) the study is sound after all.

It should be feasible for a chess engine to reach a 0.00 evaluation because there are only a few thousand drawing positions that need to be evaluated (depending on wK/bQ position, with or without the c/d pawns), and once the search has exhausted that space they'll all evaluate to a draw.

Here's a similar challenge:

[Title "NDE 1986 (2nd Prize, Israel Ring 1986)"]
[fen "5k2/1n6/1p3K2/P7/1P2N3/p1P2B2/8/2b5 w - - 0 0"]

White to move and draw.

Solution:

   1 a6 a2 2 axb7 Bf4 3 Ng5! Bb8! (a1Q 4 Ne6+ Kg8! 5 Nxf4 Qxc3+ 6 Kf5 and Black can't win; 3 . . . Bd6 4 Ne6+ Kg8 5 Nc7! Bxc7 6 Bc4+ draws.  So the Bishop crosses the critical square c7, which however White can exploit too:) 4 Nh7+! Ke8 5 Bc6+ Kd8 6 Ng5 Kc7 7 b5! a1Q (Kd6!? 8 Ne4+ Kc7 9 Ng5 repeating) 8 Nf7! positional draw.


Is blindfold chess bad for the health? From Wikipedia,

  While blindfold chess has been recommended in moderation by many sources as a method of increasing one's playing strength, simultaneous blindfold exhibitions were officially banned in 1930 in the USSR as they were deemed to be a health hazard. Mikhail Botvinnik also warned against it.

Should I actively not play blindfold chess? Are there any health risks?

No.

The main reason behind this train of thought was that they thought that blindfold chess may contribute to going crazy. They looked at Morphy and Pillsbury as their primary examples. Lasker, specifically, thought that blindfold chess made Pillsbury go mad, but we now know it was syphilis. Other than just plain incorrect assumptions like Lasker's, this is an incredibly small sample size no matter how you cut it, and we are talking about judging this on 90+-year-old "science", if you can call it that.

This not only does not make any sense in the modern day, but it has been debunked by at least USCF NM, and noted psychologist, Christopher Chabris from Harvard. The paper can be found here.

Blindfold chess is good for your chess vision, so feel free to practice it in moderation.

P.S. We have in more recent times, from 1992-2011, had the Melody Amber blindfold tournaments for the the top players in the world including Karpov, Kramnik, Anand, and Carlsen. If modern science even remotely believed that blindfold was bad for you, these guys would not have played.


Why is the Alekhine Defense named after Alekhine? Alekhine, a world champion, has his name on the defense Nf6 in response to White's e4. But after e.g. 2. e5 Nd5 3.c4 Nb6 4. d4, White seems to have a good game.

Did Alekhine win any notable games (or tournaments) using this defense? Did he publish any books or papers successfully defending this line? What did he see as its merits?

You're right in that white seems to have a good game. But in reality, not much more than that. Black continues with 4. ...d6, and can go into many variations such as the optimistic, but shaky Four Pawns Attack with 5.f4, Exchange variation with 5.dxe6, where black can respond by taking with either pawn, and will usually follow up with a kingside fiancetto if he takes back with the c-pawn. Of course, there are other variations such as the Balogh, Two pawns attack, Two Knights variation, Scandinavian variation, Modern variation (perhaps the most challenging), etc. Look them up if you wish. Black's basic idea is to get white to over-extend his center, creating targets in the form of pawns and the weaknesses left in the pawns' wake, and then undermine those weaknesses with pieces. Again, white seems to have a good game because of the classic space advantage in the centre. BUT, that's black's plan - The Alekhine Defence is a hypermodern idea, so black voluntarily gives up the centre in the opening, just to challenge it later on from the sides.

According to chessgames.com, the Alekhine's Defence has a win rate of 33.4% for black, which is very, very respectable; especially when compared to other very highly respected openings such as the Caro Kann, French, Najdorf etc.

I don't know if Alekhine himself won tournaments using just this defence, but here are a few games where he successfully employed it against strong opponents: Bogoljubov, Maroczy, Mieses, and a lesser known, but still strong Sergeant. The last game is a famous positional crush featured in a book I have on the Alekhine Defence.

Besides Alekhine, many world champions have employed it throughout history, such as Capablanca, Euwe, Tal, Bronstein, Fischer (remember the famous Spassky vs.Fischer 1972 game?), Smyslov, Petrosian, Spassky, etc. Even Carlsen has employed it now and then as a surprise weapon. Check out Carlsen vs. Topalov.

To conclude, I don't think its possible for anyone to answer why Alekhine introduced this defence (if he did), and what merits he saw. However, he must have certainly judged it to be a playable opening that matched his style (aggressive). But as I've outlined, it has become a formidable surprise weapon over time, and is even used nowadays at the very top level in major tournaments.


How to break through a stubborn Semi-Slav? With every other middlegame formation, I know more or less what I would do if I were given a load of free tempi, and thus, what I should aim for in the present. However, concerning a highly defensive Semi-Slav still with "fangs," it seems like there's not much I can do but twiddle my thumbs and hope Black opens up the position for me (which is of course a terrible strategy):

r1bq1rk1/ppn1bpp1/2p1pn1p/8/3P3B/2NBPN2/PPQ2PPP/R3K2R w KQ - 6 13

Black currently has five (!) defenders locking down d5, with the possibility of bringing in an additional rook or fianchettoed bishop if the current defenders were relocated/exchanged. Thus, I wouldn't have any idea how to launch a successful central takeover (in particular, whenever I push e3-e4 in these situations, my center pawns only seem to turn into a liability for me).

As well, the kingside is without any real defect to exploit, and starting a kingside pawn storm would (afaict) be to bet my whole position on an attack with less-than-ideal odds.

So, it seems to me that at present the queenside is White's best option to secure a weakness-free advantage. Let's say I get the opportunity for free to push my pawns and reposition my rook. The issue is that it seems Black often has the ability to liquidate the queenside at his will in his favor, for example:

[FEN "r1bq1rk1/ppn1bpp1/2p1pn1p/8/PP1P3B/2NBPN2/2Q2PPP/1R2K2R b KQ - 0 1"]

1... a5 2. bxa5 Ncd5 3. Nxd5 Nxd5 4. Bxe7 Qxa5+ 5. Nd2 Nxe7

Usually, however, Black commits to some expansion before White has the time to engineer a true queenside pawn storm, often in the form of a fianchetto for his weak bishop. This in turn tends to create a weakness on c6 that, personally, I'm glad to see, because it's at least something for White to begin to target.

But from my tabiya in the first diagram, how does White ideally want to take advantage of Black's position in the Semi-Slav, without giving himself weaknesses in the process, and without relying on Black's cooperation to loosen his own position?

The position you are looking at is indeed very common in the semi-Slav defense and the solid control of the d5 square is exactly the underlying idea for Black, often after having played ...dxc4 at some point in the opening. Looking at White's piece placement, in particular at the e pawn on e3 and the White dark squared bishop on the king's side, this seems to have originated from the classic Moscow variation, namely

[fen ""]
[Event "Merano defense, Moscow variation"]

1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c6 5.Bg5 h6 6.Bh4 dxc4

At this point White has to play aggressively to avoid Black keeping both the pawn and maintaining the initiative: the standard continuation for White is 7.e4 (that you have not played) to threaten the knight on f6 and force Black to play 7...g5 and weaken their king's side. Playing 7.e3 instead gives Black the possibility to continue developing their pieces calmly; they played possibly something like 7...Be7 but could have played instead 7...b5, pushing on the queen's side and threatening ...b4 at some point.

However, given your position on the board, White usually pursues the plan of the minority attack on the queen's side rather than going for control of the d5 square, pushing the a and b pawns to threaten b5 or c6. In order to do so it is fundamental to give rook support on the c-file with something like 0-0 followed by Rfc1. Stockfish gives the following idea, after castling:

[fen ""]
[Event "Merano defense, Moscow variation: Stockfish analysis"]

1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c6 5.Bg5 h6 6.Bh4 dxc4 7.e3 Be7 8.Bxc4 Na6 9.Bd3 O-O 10. Qc2 Nc7 11.O-O b6 12.Rfc1 Bb7 13.Ne5 Rc8 14.a3 Nce8 15.b4

and White can play trying to break on the b-c files somehow. Perhaps you want to play 12.Rfd1 instead, to avoid ...c5; dxc5 and already having control of the d-file instead.

As an example let us have a look at a famous match Topalov-Kramink, one of the many regarding (semi)-Slav variations and Queen's gambit declined as in the fashion of two amongst the most productive players of those lines:

[fen ""]
[Event "Corus"]
[Site "Wijk aan Zee NED"]
[Date "2008.01.22"]
[EventDate "?"]
[Round "9"]
[Result "1-0"]
[White "Veselin Topalov"]
[Black "Vladimir Kramnik"]
[ECO "D44"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "89"]

1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.Bg5 h6 6.Bh4 dxc4 7.e4 g5
8.Bg3 b5 9.Be2 Bb7 10.O-O Nbd7 11.Ne5 Bg7 12.Nxf7 Kxf7 13.e5
Nd5 14.Ne4 Ke7 15.Nd6 Qb6 16.Bg4 Raf8 17.Qc2 Qxd4 18.Qg6 Qxg4
19.Qxg7+ Kd8 20.Nxb7+ Kc8 21.a4 b4 22.Rac1 c3 23.bxc3 b3 24.c4
Rfg8 25.Nd6+ Kc7 26.Qf7 Rf8 27.cxd5 Rxf7 28.Rxc6+ Kb8 29.Nxf7
Re8 30.Nd6 Rh8 31.Rc4 Qe2 32.dxe6 Nb6 33.Rb4 Ka8 34.e7 Nd5
35.Rxb3 Nxe7 36.Rfb1 Nd5 37.h3 h5 38.Nf7 Rc8 39.e6 a6 40.Nxg5
h4 41.Bd6 Rg8 42.R3b2 Qd3 43.e7 Nf6 44.Be5 Nd7 45.Ne6 1-0


Looking for the right size for a box in which to store my chess set So I have this nice chess set that was gifted to me some time ago. The thing is that I don't have a proper box for the pieces (the set came in a card box, good for transportation but not for everyday storage).
I just had the idea that someone with a set similar to mine could measure their box and give me the numbers. You know, it's easy finding/building a box in which the pieces have room enough, but I'd like the proper dimensions for using just the precise space.
The sizes of the main pieces are:
king 10cm (4 inches)
rook 5.5cm (2 inches)
pawn 4cm (1.5 inches)

What would be the right size for a box in which to store my chess set?
Actually I realized that I don't need the measures of a chess set exactly like mine. Since the sizes of the pieces and the box are proportional, I just need the sizes of a couple of pieces (say king, rook and pawn) and the size of the box in which those pieces fit. The it's just a simple rule of three.
Also, it's a good idea -provided by Laska- to use cardboard for testing.

Ok, so I think I figured out a way to solve it. Since I realized I don't need a chess set exactly like mine, but just the info of any chess set (pieces and box) and then use a rule of three to scale it to my pieces set, I made a search on Google and found these results:

https://www.chesshouse.com/products/classic-chess-set-and-box-combo

https://www.rrgames.com/druke-walnut-box-with-wooden-chess-pieces.html

Probably more can be found, but I'm pretty sure that two will be enough.
Also, I'll use cardboard for testing till I get the optimal size and build the final box in wood, DMF or whatever material I choose.


Is it possible for a move to be recomended by engines but rejected by professional human players? Am wondering if it is possible for a move to be considered "good" by engines but is rejected by professional human players. One possible reason that I can think of is that the in order for this move to be successful, one has to play exactly right for the next 20 moves or so, which is easy for engines but difficult for human players.

I see three situations, where something like you describe could happen:

wild tactical positions with open king, where moves have to be very precise and many humans might be too scared to enter such position
Many composed studies feature surprising moves that could be rejected by humans. For instance studies in which you give up all your material except for say a bishop with which you mate somehow. In most positions you can't win with a bishop only, so lines leading to such positions would not be considered usually.
some of the more tricky endgames feature very unnatural/inhuman moves that would be rejected by human players. One example are the computer lines after move 67 in game 6 of the last WC match Carlsen-Caruana. Some quotes regarding the winning lines suggested by computers:

Svidler:

  Even when I saw what the machine suggested was winning there I honestly don't think it was humanly possible to find it on the 10 minutes that Fabi had, and it's incredibly weird how the position is conceptually lost after Kg6.

Kasparov:

  The computer shows Black wins with 68..Bh4 here. But had Caruana played the incredible 69.Bd5 Ne2 70.Bf3 Ng1!! they would request metal detectors immediately! No human can willingly trap his own knight like that.

Svidler:

  A move that a human is more or less incapable of making

Grischuk:

  I would never even dream about Bh4

Carlsen:

  I’m not going to disagree with the computer, I just don’t understand it!


Check and checkmate on following moves I was playing chess with a buddy, and I put him in check. On the following move, without moving his king out of check, he moved a rook to put me in checkmate.

My questions are as follows:

Can he do that and leave his king still in check?
Even though I'm in checkmate, can I take his king to win the game?
Is checkmate an automatic win (meaning no moves can follow), or can I still "try"?
If it was an illegal move, where do we resume?

No, this is not legal.
Not relevant since 1 is illegal.
Checkmate is a win and no moves can follow.
You go back to illegal move and correct if its a friendly game, I don't know what the official rules are for when a player makes an illegal move.


What is the order of actions in chess under FIDE rules? Reading some recent posts about the 50 move rule made me realize that I've never seen an explicit order of actions for chess. By way of comparison, the order of actions in Monopoly is given here:
(1) Throw the dice
(2) Move the indicated distance or to jail (if 3rd double in a turn)
    - collect $200 if land on or pass Go
(3) Resolve space
    - ownable properties
        = pay rent if owned and not mortgaged
        = buy it if unowned (optional)
        = auction property if still unowned (not optional)
    - non-ownable properties
        = resolve as indicated.
        = collect $200 if resolving puts you passing Go.
(4) Pass the dice or roll again, as appropriate.

A chess move combines three actions (shifting wood, writing move, hitting clock) and the game can end in various ways (mate, stalemate, dead position, agreement, 50 move rule, 3-fold repetition, 75 move rule, 5-fold repetition). For simplicity, let's put to one side for now resignation & irregularities e.g flagfall).

The FIDE Laws of Chess provide some guidance.

Rule 6.2.1 says you must move the piece before hitting the clock:

  During the game each player, having made his move on the chessboard, shall stop his own clock and start his opponent’s clock (that is to say, he shall press his clock). This “completes” the move.

According to rule 8.1.2, you must move the piece before writing down the move, usually:

  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

There is a little bit of flexibility as to when exactly you write down the moves, according to 8.1.3:

  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.

So, you must move the piece before doing anything else.  Ordinarily, you would then hit the clock, and finally you would write down the move.  I am not sure if it would be a violation of 8.1 to write the move after moving the piece but before hitting the clock - technically, the move is not "completed" until the clock is hit - but it gives no benefit to do so.  In practice I've only seen it when someone forgets to hit the clock altogether.

Offering a draw is done after making the move but before hitting the clock, and claiming a draw is done by writing down the move but not playing it, and seeking the arbiter.

The 5-fold repetition and 75-move rule may be claimed by the arbiter whenever applicable, so you can't really give them any set place in the order.

This gives us the following order:

(1) If claiming a draw:
     - Write move (if this move is required for draw)
     - Stop clocks (not required, but wise)
     - Declare draw claim to arbiter
     - If claim is upheld, game is over

(2) Make your move on the board
    - If this move results in checkmate, stalemate, or dead position, game is over

(3) If offering a draw, offer draw to opponent
    - If opponent accepts draw, game is over
    - If opponent declines, or delays decision, proceed to (4)

(4) Press clock
    - (Probably this could be done after (5), but this order is preferred)

(5) Write move


Openings that Black has success with statistically? I love the B06 Modern Opening for Black:

[Title "White - Black"]
[FEN ""]

1. e4 d6 2. d4 g6 3. Nc3 Bg7 4. Bc4 e6 5. Nf3 Ne7 6. Bg5 h6 7. Bh4 a6 8.O-O Nd7

I find it leads to a strong position for White to attack and a secure one for Black to defend (especially if it leads you to the Hippo Defense because, as Black, I've had my greatest success with atypical openings:

[Title "Petrosian vs. Spassky, World Championship 1966 (game 16)"]
[FEN ""]

1.d4 g6 2.e4 Bg7 3.Nf3 d6 4.Be2 e6 5.c3 Nd7 6.0-0 Ne7 7.Nbd2 b6 8.a4 a6 9.Re1 Bb7 10.Bd3 0-0

Question: What are the major defences that statistically have seen the most success by Black?

It depends very much on what you intend by the word "advantage": if you are asking

  Are there any openings that give Black advantage at correct play?

the answer is obviously no, as well as there are no openings that give White advantage, at correct play. If otherwise there will just be no openings, rather only that one line that always gives advantage to White (or Black, respectively) without any need to play anything else. At correct play all standard opening variations are equal, if only there might be a tiny slight advantage for White in the sense that it is enforced to play the next move and as such the next-to-come threat.

If instead you are asking

  What are the major defenses that statistically have seen the most success by Black?

that is another matter completely. You might want to have a look at any of the large chess databases present on the internet where openings are sorted by winning percentages according to the variation (for the games contained in the database, obviously); an example is this page from ChessTempo showing winning percentages for the Sicilian Najdorf variation, for instance, that is well-known to be among the most played defenses versus 1.e4. Other examples for 1.d4 are the Slav defense or the Indian defenses, as standard sound counterplay for Black.


Xiangqi symbols in Unicode Since Chess symbols are part of Unicode, I would like to know if Xiangqi symbols would be too.

If they are, where can we find them?
If they are not, is there a way to find some... in Unicode for instance?

Xiangqi symbols are now in Unicode 11.0, in the block Chess Symbols: U+1FA00–U+1FA6F.


Most beautiful checkmates? What is the most beautiful checkmate you've ever seen in high-level play? The beauty might be caused by one of the following:

A brilliant setup (the couple moves preceding the mate were brilliant)
Totally unexpected/against the odds (for example, the other opponnent was up a lot of material)
Swiftness (of course no fool's mate or such)
etc.

Check the list of Immortal games listed here :http://www.chessgames.com/perl/chesscollection?cid=1000589

Especially enjoyed Paul Morphy vs Duke Karl : http://www.chessgames.com/perl/chessgame?gid=1233404

and Lev Polugaevsky vs Rashid Gibiatovich Nezhmetdinov (this is simply stunning): http://www.chessgames.com/perl/chessgame?gid=1111459


Could Karjakin have grabbed on g5 at move 56 against Anand in the Candidates 2014? After 55...Rb2, we got the following position in Karjakin - Anand (Candidates 2014, round 13). Well, how about Nxg5, does it work?

[White "Karjakin"]
[Black "Anand"]
[FEN "8/8/6k1/4p1p1/4P1Pp/5P1N/1r1BK3/8 w - - 0 1"]

1.Nxg5 Rxd2+ 2.Kxd2 Kxg5 3.Ke3 h3 4.Kf2 Kf4 5.Kg1 Kg5 6.Kh1

Seems better (winning?) for white. Am I missing something?

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

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

Note that:

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

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

1.f4 exf4

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

Or white can play 4.f4 immediately.

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

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

So the pawn endgame is a draw.


Why sacrifice the rook? [Title "White to move"]
[FEN "1r3rk1/1p4bp/p2p1q2/2pPn1p1/B1PnRp2/PPN2P1P/2QB2P1/3R2K1 w - - 5 27"]

This is a diagram from the game between Del Rey, Diego and Efimenko, Zahar on the Zalakaros Chess Festival after 26...Nd4. White answered with 27.Rxd4. I don't understand why white needed to sacrifice his rook for the knight in this position.

Well, he has to because there is no other option. The black Knight threatens to capture the white Queen, but also a 'sacrifice' on f3 which will eventually win the white Knight on c3.

[Title "White to move"]
[FEN "1r3rk1/1p4bp/p2p1q2/2pPn1p1/B1PnRp2/PPN2P1P/2QB2P1/3R2K1 w - - 5 27"]

1. Qb2? Ndxf3+ 2. gxf3 Nexf3+ 3. Kg2 Nxd2 4. Qxd2 Qxc3

This might not even be the best variation for Black. In any case, even after the sacrifice, White is still lost.


Why doesn't white play Bd2 after this ...Qa5+? I was looking at an analysis which shows this position ( from Bacrot - McShane 2018). At this point Black just played ...Qa5+, and the only moves that are analyzed for white are Kf2, c3 and Qd2.

This is not the first time I see such a position, and I never understood why Bd2 is not even considered. As a black french player, I often discard moves like ...Qa5+ because it looks superficial to me after Bd2. But by looking at these games, it clearly looks like I'm missing something important here.

Any pointers ?

r1b1kb1r/3n1ppp/p1n1p3/qpppP3/3P1P2/4BNP1/PPP1N2P/R2QKB1R w KQkq - 1 10

The point here is that Bd2 blocks your queen's mobility and also leaves the defense of the d4 square. So after say Qb6 you pretty much have to go back with Be3, which will move closer to a draw by threefold repetition if blacks continues again with Qa5+.

Also if after Qb6 you play c3 instead of going back with the bishop, now your bishop is not well placed, and black's Queen on the other hand is very good on b6. So its safe to say that you kind of lost some piece coordination in the process.

One of ideas behind Kf2 is that you are pretty close to castling by hand with only two moves, such as Bg2 and Re1, and on the other hand black's Queen is misplaced on a5 and will most likely reroute later on to other squares.

All this being said, its still important to note that Bd2 is not a bad move. When i let Stockfish run for one or two minutes i see a diference of 0.1 for both moves. It gives 0.4 for Kf2 and 0.3 for Bd2, so its just an ok move.


What are some good books for chess openings? I am not new to chess, I have been playing for around 6 years. But I don't know much about chess openings technically. What are some of the very good books to to learn important opening moves?

Thank you in advance.

There are two excellent modern surveys of openings: Sam Collins' Understanding the Chess Openings and Paul van der Sterren's Fundamental Chess Openings. They both cover every major opening, demonstrating the main ideas and variations. I would start with Collins, since it is shorter and easier to read through in its entirety, but both are highly recommended.


Online chess with full disclosure of name and FIDE ID I would like to play online chess via an interface where name and FIDE number are disclosed, mainly because I believe that this discourages engine users.
A few questions:

I found the FIDE Arena application, and thought it indeed required
disclosure of personal info, but after trying it out it
doesn't seem so. Is that perhaps only a requirement for paying
users? Any info what be appreciated on this.
Any other platform that enforces such a requirement?

Only FIDE could enforce that.  Talk to them.
No other platform can or does do that.


What's the name of this set design? I'm looking to buy a nice wooden set and board, something I've wanted for a long time. I have this Kasparov vs Karpov picture as my desktop background

and I love the set, but I can't find one quite like it. Does anyone know the name of this style of set, or where I could get one?

From Tony Rotella on the reddit page I pointed to this one:

  They're DGT "Timeless" pieces: http://www.digitalgametechnology.com/index.php/products/eboard-chess-sets
  This has been a very standard FIDE design for a long time, though there have been slight modifications over the years to (at the least) the pawns and bishops I believe.
  You might also be interested in these, which are basically the same: http://www.houseofstaunton.com/the-championship-series-chess-set-3-75-king.html


How to play against an engine using scid for a particular level? The best free chess program SCID vs Pc is installed and the latest chess engines are installed. After watching video Jeremy Silman, to play for first low level then intermediate and then Master level.

How to configure the SCID vs. PC to select a Particular chess engine , to play Low level or intermediate or then Master level ?

Manage your engines in Tools.

Select your engine in Play.

Configure the engine, then select your skill level.


List of Crazyhouse engines I want to get a list of all (because they are certainly only a few existing) crazyhouse engines. I searched in lichess forum posts by googling "crazyhouse engine" and collected many names and links from 3 different posts.

Initial list, to complete:

Sunsetter

Stockfish (a well known engine, recently implemented for crazyhouse, seems to be the strongest for this variant in this thread, is the default used in lichess for crazyhouse, important news: has beaten jann lee consistently in informal match in this playlist)

Sjeng

Tjchess

Immortal

nebiyu

pulsar

sjaak

Crazyhouse by nathanlo99

From the computer list of the Crazyhouse Chess Variant Association:

Sjeng
KKFchess
Pulsar
Nebiyu Alien
Imortal
Sjaak
TJchess
TSCP zh
Sunsetter
CrazyWa

And aside from that there is the multi-variant Stockfish that plays Crazyhouse.

And Crazyhouse by nathanlo99


Could you explain me this part of GM Larry Kaufman's article on "The Evaluation of Material Imbalances"? This is a stupid question that has more to do with English than with chess, so if other people also think it's stupid I can delete it after I get the answer.

Since English is not my mother's tongue I am not totally sure I understand correctly this part of GM Larry Kaufman's article on "The Evaluation of Material Imbalances".

There are many things I don't understand everywhere, but this thing is particularly important to me so I really want to be sure that I understand it correctly.

  TO SUMMARIZE

  To summarize the findings of my research, the basic table of values would be:

  Pawn= 1
  Knight =  3.25
  Bishop = 3.25
  Rook =  5
  Queen =  9.75
  Bishop pair= +0.5

  This table agrees with the statistics (within about 1/8 pawn accuracy) in nearly every case tested.

  A further refinement would be to raise the knight's value by 1/16 and lower the rook's value by 1/8 for each pawn above five of the side being valued, with the opposite adjustment for each pawn short of five.

If I understood the part "raise the knight's value by 1/16 and lower the rook's value by 1/8 for each pawn above five of the side being valued" then these are the average values of our Knights and Rooks according to our number of Pawns:

If you have 5 Pawns your Knights are worth 3.25 and your Rooks are worth 5
If you have 6 Pawns your Knights are worth 3.3125 and your Rooks are worth 4.875
If you have 7 Pawns your Knights are worth 3.375 and your Rooks are worth 4.75
If you have 8 Pawns your Knights are worth 3.4375 and your Rooks are worth 4.625

Is this correct?

But what I'm really not sure of understanding is the part where he says "with the opposite adjustment for each pawn short of five."

Firstly, does "short of five" mean this?:

1 pawn short of five = 4 pawns
2 pawns short of five = 3 pawns
3 pawns short of five = 2 pawns
4 pawns short five = 1 pawn
5 pawns short of five = 0 pawn

And therefore, does "with the opposite adjustment for each pawn short of five" mean:

this: Lower the knight's value by 1/16 and raise the rook's value by 1/8 for each pawn short of five of the side being valued. ?
or this: Lower the knight's value by 1/8 and raise the rook's value by 1/16 for each pawn short of five of the side being valued. ?

PS: No need to tell me that implementing this in practical play is perfectly useless.

Your interpretation of "for each pawn above/short of five" is correct. Unfortunately, "the opposite adjustment" is vague and could mean either of the two things you suggest.

I would guess that it means the first one, so that the value of a knight decreases by 1/16 every time a pawn is captured and the value of a rook increases by 1/8. If that is true, a simpler way of expressing the values would be that a knight is worth 2 15/16 plus pawns/16 and rook is worth 5 5/8 minus pawns/8.  (Which, as you say, isn't very useful in practice.)


Does chess.com analysis board use my own CPU? Lichess analysis board uses my own cpu so I am just curious if chess.com also uses my own cpu.I have tried searching but I can't find any information about it.

Yes, it does. It uses stockfish.js, the Javascript port of Stockfish, which can run on web browsers. You can see stockfish.js mentioned somewhere on the chess.com analysis board. Also, I can tell that the computer fan starts working harder when I run an analysis, and looking at the "top" command shows that the web browser is using 100% CPU.


How to define a countergambit? Am wondering if there is a definition of a countergambit. My understanding is, a countergambit happens when one side plays a gambit, instead of capturing the pawn, the other side also sacrifices a pawn.

Is my description accurate? Is the following line considered as a counter gambit?

f4 e5 2. e4

The move e5 is called From's gambit. Instead of capturing the pawn, white develops his king pawn, offering his f4 pawn. Is this considered as a countergambit? (Under a different move order 1. e4 e5 2. f4 it is called king's gambit.)

You're right: a counter-gambit is an opening in which one side plays a gambit, and the other side rejects the gambit with another gambit (i.e. "gambits" the gambit). A popular counter-gambit is the Albin Countergambit:

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

1. d4 d5 2. c4 e5

  Under a different move order 1.e4 e5 2.f4 it is called King's gambit.

This is also a King's gambit but due to the order it is also cosidered a countergambit

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

1. f4 e5 2. e4


Reviewing Chess Tactics Puzzles Is there somewhere online I can play chess tactic puzzles and redo them whenever I want? I do tactics on lichess but it doesn't store my puzzles. Is there somewhere that stores all my tactic problems so I can redo them? I feel that would be better to develop pattern recognition. Thanks in advance.

If you have a premium membership on ChessTempo, you can create problem sets with spaced repetition, which is one of the advanced options under problem search. If you select this option, the site will show you both new puzzles and puzzles you've already solved. You'll see puzzles you've gotten wrong more often, and if you get a puzzle right a few times, you won't see it as much.

Lucas Chess, which is a desktop program and free to download, also includes sets of tactics puzzles for training using spaced repetition.


Najdorf threefold repition In the Sicilian Najdorf there is a well known line which ends in threefold repition (if both players want).

[Event "NN"]
[ECO "B90"]
[Opening "Sicilian Defense: Najdorf Variation, English Attack, Anti-   English"]
[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 Ng4 7. Bc1 Nf6 8. Be3 Ng4

Since white retreats the bishop to c1, the positions after 5. ... a6 and 7. Bc1 are almost the same (only difference is that the knight is on g4 now) and since it is black's turn, black gained a tempo (if not for the knight's position on g4).

Two questions on this line:

Why does black have to return the knight to f6? Aren't there any other useful moves that he could make and only retreat when being attacked?
Ignoring any match situation or Elo difference, etc, both players insisting on this repetition, does it mean that Be3 is the best 6th move in the Najdorf for white and does it mean that normal play with 6... e5 is very dangerous for black?

does it mean that Be3 is the best 6th move in the Najdorf for white
  and does it mean that normal play with 6... e5 is very dangerous for
  black?

"No" is the answer to the first question and "Not really but in any case, as hoacin points out, there are plenty of reasonable alternatives for black" is the answer to the second question.

Look, whether it is true or not, the vast numbers of cynical ordinary club players like me strongly suspect that every time a game like this was played it was preceded by the players meeting in the bar the night before and agreeing a draw and then picking their favourite "forced draw" variation.

When challenged the players will come out with standard BS along the lines of "Well, I spent hours preparing the X variation [say first 5 moves above] because I know my opponent plays that line a lot. All my preparation was based around move 6 and I expected he would play move y [obviously a different choice from the drawing variation] and when he didn't I had to fall back on the repetition line".

It is complete hogwash. Everybody knows it. But if both players have decided, for perfectly good reasons [tournament situation, tired after previous long hard game, minor illness - cold, stomach bug, etc., opponent is a close relative] that a draw is what they want then there isn't much anybody can do about.


A question about chess literature I am looking for a chess book written in a very engaging style and thoroughly professional manner. The book should be more along philosophical and psychological lines rather than notations and arithmetic.
I would appreciate any help, preferably from those who are keen chess literature lovers.

You should check out books by GM Jonathan Rowson. As well as being a GM he is a philosopher. After his first degree in Philosophy, Politics and Economics at Oxford University he spent a year at Harvard University before doing a PhD in Wisdom at Bristol University. He is currently director of the Social Brain Centre at the RSA (UK Royal Society for the encouragement of Arts). Most of his chess books have a strong philosophical and psychological content and bias.
You should check out:

The Seven Deadly Chess Sins
Chess for Zebras
The Moves That Matter: A Chess Grandmaster on the Game of Life