What can you deduce from my performance in different types of chess tactics? So each day I practice a different tactic.  So my tactics training regimen is like this (Chess Tempo)

Day 1:

5 problems - (standard) specific tactical motif (i.e. discovered attack, sacrifice, fork/double attack, etc)

5 problems - blitz

5 problems - mixed

Day 2:

5 problems - (standard) specific mate type

5 problems - "problems I've gotten wrong at least once"

5 problems - standard

And I alternate everyday doing that.  I keep a log to record how well I am doing.  If over three consecutive runs of the same tactic, I end up scoring a 13 (out of 15) or better, I will up the difficulty by 200 points (right now I have all the specific tactic-type sets limited to 1400-1700).  My Chess Tempo standard tactics rating is around 1600.

Right now, I am not even done with one round, but so far I have this:

Advanced Pawn   5

Attraction  3
Avoiding Perpetual  2

Avoiding Stalemate  3

Back Rank Mate  3

Blocking    4

Capturing Defender  2

Clearance   2

Coercion    3

Counting    3

Defensive Move  1

Desperado   3

Discovered Attack   3

Distraction 4

Double Check    2

Exposed King    4

Mate - Anastasia's  3

Mate - Balestra's   1

Mate - Arabian  5

Mate - Backburne's  5

Mate - Boden's  4

Mate - Damiano's    5

Mate - Damiano's Bishop 4

Mate - Double Bishop    5

Mate - Dovetail 4

Mate - Dovetail - Bishop    4

Mate - Epaulette    3

Mate - Escalator    3

Mate - Greco's  3

What can you deduce from my performance in various tactics types, in terms of my strengths and weaknesses as a player (tactically)?

Chess tactics frame different positions which we sometimes come across the Board . It may be Double attack , fork , Pin and many others . Just solving the Chess tactics lone is never the measurement because when you solve a tactic you know already that there is a sacrificial or a combinational move which will make you win or help to solve the tactic . In real games sometimes you even get an easy position but you fail to find the best move OTB .

Solving tactics just make you at ease that you are doing something and practicing Chess but it is never the complete homework to make the best judgement .

A different way to find the performance measurement is that how good you are making a calculation or even finding your own weaknesses in specific patterns . like for an example you have a habit of leaving your piece hanging in your own games . So you must solve tactics relating to Hanging pieces which will help to improve your weak point . They say in whichever tactic you find it difficult to solve you have a weakness in that area .


1700 rated games-On mistakes and how to correct them What are some typical mistakes in 1700 rated games on Lichess, and what ways are there to correct them? I usually play blitz and bullet games. Occasionally I play. OVB and longer formats.

Even at 1700, the vast majority of your mistakes are going to be tactical errors...especially at the faster controls. The only way around that is to start studying and practicing.

There may be some people, who can benefit from online tactics, but am of the belief that they lend themselves toward the trainee being shallow, and often the answers are the computer answer, not the human answer.

I am a firm believer in books, so get yourself some good tactic books that are well-categorized. It is better to study specific categories at one time, pins, skewers, etc. I still love the Fred Reinfeld 1001 books.

Try to do 50 per day, spending no more than two minutes per problem. Note in pencil on a scale from 1-5 how easy you found the problem because you will do them again in the future. The more time you spend on tactics, the less you will lose online.

One last thing, and that is I have found that even mid-level players think they are pretty good at tactics, but it is my experience that they are not. I am no longer above 2200 USCF, but even when I was, I always felt I could be stronger at that, and general calculating.


Most important aspects of computer for scanning through databases in Chessbase? A quite technological question so this is for the tech-people out there!

What are the most important parts of a computer for Chessbase Database searching? For example, opening reports and reference, as on my current laptop it is fast but scanning through popular variations can be time-consuming which is not practical for overnight preparation.

There are really 4 components to your computer's speed and the speed that a program will achieve. These are:

1) Disk speed. For big database searches this is probably the most important. The faster the disk the better so you probably want to store your data on an SSD if possible.

2) The amount of memory. If large amounts of data are involved and the program is well written to take advantage of as much memory as you have then this is very important. For large commercial databases run by big businesses the default solution to poor performance is to add more memory but here I am talking about relational databases like Oracle, DB2, SQL Server etc. Still important for a chess database program if it is well written.

3) Number of cores or processors in the CPU. If the program is written to support multi-threading (and if it is any good then it should) then the more cores the faster it will run.

4) Raw CPU speed. This is probably the least important but still important particularly for poorly written single-threaded programs.


Bughouse defense patterns What defensive patterns and structures are used in Bughouse and Crazyhouse? I've heard that castling is rarely useful, but what should be done instead? My defensive play usually boils down to huddling in the "turtle formation":

[FEN "2rqkr2/pppbbppp/2nppn2/8/8/8/8/8 w KQ - 0 1"]

Turtling exaggerated for dramatic effect

This is entirely ineffective and quickly results in mate.

How can I defend in bughouse?

In general, in a bughouse game, one of the players in the team attacks while the other team member defends. Thus, when the defender gets attacked, the attacker sacrifices a lot of material. This material goes to the other team member (attacker), who can the use the material to fuel their attack. Thus, the defender loses (or saves) the match. Defensive strategies are therefore very important indeed.

The key square is usually the f2-square for white (f7 for black). Let's focus on black defending, since that is usually the case. Thus, the f7-square is critical. White will sac a bishop on f7, drop a knight on g5 and something diagonal on f7, leading to a quick win. The basic idea is to defend with e7-e6, blocking the a2-g8 diagonal. Yet, white can drop a pawn on f5 or sac a knight on f7 and drop a second knight on g5.

The main problem is that white can drop a pawn on h6 and open up the g7 and f6 squares for attack. If black plays h7-h6, then white drops a pawn on g6, attacking on f7. If you have to castle, then usually kingside is preferred, since queenside is vulnerable to a heavy piece dropped on a8 followed by a knight getting to a7. Also, a white pawn getting to a7 with a black king on c8 is a killer. Kingside castling makes the pawn drop on h6 perhaps even more deadly. Also, h7 starts becoming an issue.

So, here are a few tips how to survive as black against white attacking:

Drop an extra pawn on h6, so you get an f7, g7, h7, h6 pawn structure.
Play e7-e6
Drop a bishop on g8 to support f7
Always have a pawn, bishop or knight on f7 (never the king)
Drop a pawn on f6 (after getting a pawn on h6) getting more control over g5 and e5 (where white tries to place a knight)
Be ready to sac a queen on a white knight on g5 to buy time
Never move the c-pawn or f-pawn. In general, avoid any pawn moves, unless you are sure about what you are doing. After the c-pawn moves, c7 and d6 become weak, which is simply lethal.
Exchange your bishops for the opponent's knights by pinning them to the enemy queen or king (check with your team mate if knights are good). In general, keep those enemy knights pinned. E.g. drop a bishop on h5 to protect on f7 and pin the Nf3 to Qd1.


Ideal move in this situation https://en.lichess.org/training/5571

Why is White knight to f5 not an ideal move in this situation? As far as I can see, unless Black takes the white bishop with the rook, it's mate in 2.

The puzzle is a mate in 3 starting with a rook check. After knight to f5, there is a mate in 4 on the board, so that line is a mate in 5.

Of course one forced mate is as good as another, but if you did want to differentiate between forced mates of different length, then an argument can be made that fewer moves is better.  This is certainly how lichess does it in these puzzles, though it is certainly annoying if such a move is judged as a mistake.  Sometimes you get an admonition that your move although good is not the best and that is less annoying though arguably also incorrect.


Would an erroneous claim of mate be considered as annoying the opponent, cheating, an illegal move, or something else? Especially in kiddie games, mates are often missed or supposed mates are not really mates. What would the TD declare such misguided claims of mate? What should a TD do if adults did the same thing?

First, kids and adults, the rules are the same, so there is no difference there.

What you are asking about goes beyond just the rules: It comes down to intent.

Whether an adult, or kid, there could be an erroneous claim; and if it is really just that, then the TD should just fix it assuming it is caught in time. It is just a mistake. Other types of mistakes would be similar.

This might be hard to prove, but it an opponent did it just to cheat or annoy, then yes, that would be a breach of the rules, and should be penalized. The real question is how do you prove that? Short of the person having done it before, or bragging about it, I cannot see how a TD would impose sanctions upon someone for what otherwise looks like a human mistake. I think the TD has to assume it is a mistake unless otherwise proven, which again, may be next to impossible. Even without that proof, if the TD suspects, a warning may be in order that future incorrect claims may be sanctioned.


Why is this King and Pawn ending lost for White? [FEN "8/8/8/3pk3/1K6/8/8/8 w - - 0 1"]

Even with White to move, the game is lost. OK, but according to what rule/principle?

With 1. Kc3

I'm able to get first to one of the key squares (c3,d3,e3)
I get the diagonal opposition with the black King
I can occupy the black's promotion square before the black's King

In spite of all that, the ending is lost. Is it because I can't keep the oposition?

p.s.
The point of all this is to be able to evaluate this basic position only by applying rules, not having to calculate the concrete variations.

If you want to evaluate this ending with general rules, the rule of key squares is a good way to deal with it. However, this rule doesn't say "whoever reaches a key square first will get the result he is aiming for", it says "if the offensive king (here, Black) reaches one of the key squares, he will win."

Here after 1.Kc3 Ke4 2.Kd2 Kd4 you cannot prevent Black's king to reach one of the three key squares, so you lose.

[FEN "8/8/8/3pk3/1K6/8/8/8 w - - 0 1"]

1.Kc3 Ke4 2.Kd2 Kd4 3. Kc2 (3. Ke2 Kc3) Ke3


Why is 16. d5 a blunder in this position? In this position I'm White and I have just played 16. d5. Stockfish labels the move as a blunder. I do understand I had better moves than this, and it's not the move I would play if I were to get this position again, but why is it a blunder? It doesn't seem that bad. My reasoning was that, having the bishop pair and better development (two minor pieces playing versus one), and Black having a somewhat vulnerable king, I could benefit from opening some lines with the pawn-break.
rn4k1/pbp1qr2/1p1pp2p/3P1pp1/2P5/2PBP1B1/P1Q2PPP/R4RK1 b - - 0 16

The move 16. d5 is not necessarily a blunder. Although it is not good for White, it is not losing. Lichess and other chess engines sometimes see positions differently from how humans would percieve them.

That being said, analysis on chess.com deems it a a mistake. which is much more reasonable. The reason is that, in the long-term, the d5 pawn mught be lost, giving Black a +1 advantage, in material worth, at the least in some lines.  Even if White retains a pawn, the doubled pawns on the queenside will be a disadvantage that Black can use, or there will be some other disadvantage Black can create for White.

All in all, White will have some sort of positional weakness no matter the outcome.

Here is a computer generated line that shows how Black gets the upper hand in the long-term with an extra pawn. I do not claim that this is the 100% best play, just that it shows one of the many general outcomes where Black has an advantage.

[FEN "rn4k1/pbp1qr2/1p1pp2p/5pp1/2PP4/2PBP1B1/P1Q2PPP/R4RK1 w - - 0 1"]

1. d5 Nd7 2. Rae1 Raf8 3. f4 Nc5 4. e4 fxe4 5. Bxe4 gxf4 6. dxe6 Bxe4 7. Rxe4  Nxe4 8. exf7+ Rxf7 9. Rxf4 Rxf4 10. Bxf4

Note that although f4 is technically an inaccuracy, it is perhaps best by human play.

Here is another line that shows how Black can get an advantage in other ways as a result of White’s mistake.

[FEN "rn4k1/pbp1qr2/1p1pp2p/5pp1/2PP4/2PBP1B1/P1Q2PPP/R4RK1 w - - 0 1"]

1. d5 Nd7 2. Rae1 Raf8 3. f3 Ba6 4. Be2 e5 5. e4 f4 6. Bf2


What's with ChessBase and WB engines? I've been using ARENA for quite a while(5 years to be specific) and I have a collection of Winboard engines that I love. I recently parted with $140 to buy Fritz 14. But to my dismay it doesn't support Winboard engines. This is a big disappointment considering the cost of the product. How can I get my favorite WB engines to play in the FRITZ GUI? Why doesn't ChessBase include native WB support with their products?

ChessBase products only support two protocols:

1) Their own proprietary (used by the .eng engines)

2) The UCI (used by by many commercial / open source engines)

You must see a "Create UCI Engine" option in either Fritz or ChessBase (I used it all the time to make tournaments between engines).

I also use Arena for engine tournaments and supports both UCI / Winboard. You should be able to use UCI engines in both Arena / ChessBase.

Some notes:

There are adapters for Winboard to UCI like Good UCI to WinBoard adapter (but I don't have seen the opposite).
I have learned that whenever I have to buy a commercial engine (like Houdini or Komodo) I prefer to not buy it thru ChessBase (because they only provide the .eng and only works in their own interface).


D4 D5 C4 NF6 Continuation I'm a quiet and positional player rated in the 1400's and play exclusively online correspondence chess. I always play D4 with white as first move and usually C4 after that.

One opening I come into quite often is D4 D5 C4 NF6

After this what is the most solid play for white to get a strategic advantage for long term correspondence play?

This opening 1.d4 d5 2.d4 Nf6 is known as the Marshall Defense of the Queen's Gambit Declined.  White can get an advantage with 3.cxd5 resulting in an advantage, such as 3...Nxd5 4.Nf3 Bf5 5.Nbd2 Nf6 6.Qb3 Qc8 7.g3.

However a lot of those lines involve wide open tactical play, and you are looking for a quiet positional alternative. Therefore simply 3.Nc3 when Black can choose between several different openings.

The main line Queen's Gambit Declined with 3...e6 4.Bg5 Be7 5.Nf3.
The Slav with 3...c6 can get tactical, so maybe play 4.e3 Bf5 5.Nf3 e6 when 6.Nh4 is popular, to get the advantage of two Bishops.
The Queen's Gambit Accepted 3...dxc4 4.e3 or 4.e4 and you should easily regain the pawn.
The Grünfeld Defence 3...g6 can also get quite tactical. 4.Bf4 Bg7 5.e3 O-O 6.Rc1 is one way to steer the game away in a quieter direction.


Stockfish is considering a move in a book by GM Mihail Marin as a blunder In the book English opening volume 1 by Mihail Marin at this position
[fen "3nrrk1/bppq2p1/p4p1p/2Pp4/1P1P3N/P1BQ2P1/5PKP/4RR2 w - - 2 21"]

1. Qg6 (1. Ng6)

He suggests Qg6 whereas stockfish suggests Ng6 and evaluation drops from +4.3 to +1.1 after Qg6. I know this is analysed by humans but I am confused about reading rest of the book because I cant trust it now. Any suggestions?

Mihail Marin simply missed that 1.Ng6 is winning, even faster than 1.Qg6. During opening analysis, and even during a game, sometimes when you find a satisfying continuation you forget to follow Lasker's advice and look for an even stronger one.
This is a slight mistake in his analysis, but his evaluation of the variation remains correct (White is winning, even faster than he thought) and I see no reason not to continue studying his book and learning from it.
No chess book is completely void of analysis mistakes. If this is the worst one in the book, then the work is still very trustworthy. However, I encourage you to keep your good habit of checking the author analysis, with your own mind and with engine: First, to prevent falling for a bigger hole in a flawed variation if there is one ; Second, to better understand and remember the positions.


Are there any bughouse chess engines? A friend told me its very hard to implement a bughouse chess engine because it requires much more processor power than a regular chess engine.

Are there any bughouse engines out there ? if not, what are the reasons ?

There are certainly several chess engines, but as a result of the additional complexities referenced by @TonyEnnis, these engines are weaker than reasonably strong players. It's extremely difficult to take into account the different scenarios that can arise from two positions as pieces switch from board to board every move. The resulting search tree increases at an exponential rate even greater than that of standard chess.

The engine that I'm most familiar with is Sjeng which claims that it has an ELO of around 2000 on FICS, equivalent to a strong human player.


Is there a list of unsound openings? Not so long ago I was looking for a comprehensive list of openings (and received an excellent answer with a huge list). Hearing a lot about unsound openings, I am curious whether I can have a comprehensive list (I have read this answer, but it is just a few gambits) of unsound openings.

This is not an answer, just an explanation why it is difficult to generate a list of unsound openings.

There is the famous quote "Any opening is good enough to be played if its reputation is bad enough" - Tartakower. This tongue-in-cheek quote implies that there are many good ideas in openings which are considered refuted or unsound. More specifically, "If an opening cannot be refuted by concrete variations, it is playable, even when it appears on the verge of catastrophe" - Averbakh. So, for an opening to be considered unsound, it has to fail to some specific tactic.

Lets highlight this with a game. The game below is a mismatch between Karpov (elo 2725) against Miles (elo approx. 2575). Miles plays the eccentric St George variation, 1. e4 a6 and wins! Miles chose this opening because he knew Karpov had an encyclopedic knowledge of all the mainstream openings.

[White "Karpov"]
[Black "Miles"]
[FEN ""]

1. e4 a6 2. d4 b5 3. Nf3 Bb7 4. Bd3 Nf6 5. Qe2 e6 6. a4 c5 7. dxc5 Bxc5 8. Nbd2 b4 9. e5 Nd5 10. Ne4 Be7 11. O-O Nc6 12. Bd2 Qc7 13. c4 bxc3 14. Nxc3 Nxc3 15. Bxc3 Nb4 16. Bxb4 Bxb4 17. Rac1 Qb6 18. Be4 O-O 19. Ng5 h6 20. Bh7+ Kh8 21. Bb1 Be7 22. Ne4 Rac8 23. Qd3 Rxc1 24. Rxc1 Qxb2 25. Re1 Qxe5 26. Qxd7 Bb4 27. Re3 Qd5 28. Qxd5 Bxd5 29. Nc3 Rc8 30. Ne2 g5 31. h4 Kg7 32. hxg5 hxg5 33. Bd3 a5 34. Rg3 Kf6 35. Rg4 Bd6 36. Kf1 Be5 37. Ke1 Rh8 38. f4 gxf4 39. Nxf4 Bc6 40. Ne2 Rh1+ 41. Kd2 Rh2 42. g3 Bf3 43. Rg8 Rg2 44. Ke1 Bxe2 45. Bxe2 Rxg3 46. Ra8 Bc7 0-1

To answer your question, you would need to figure out which openings have a concrete tactical refutation, rather than ones that are offbeat.


Is the following endgame position a draw or white has advantage? Hello, this is my first question on this site. Is the above position a draw or an advantage for white? I checked a few engines at different depths, some say it is advantage for white , some say it is draw.

The general strategy I guess for white would be to play Kf4 and try to win the g pawn. Black's king is temporarily unable to come to the 7th rank due to the white pawn and bishop combine. But can white win the g-pawn without letting go of his own pawn ?

Thanks.

This endgame is a clear draw.

Black simply has to maintain his king on f8 and keep the bishop alive and White cannot make progress.

The only way White can win this position is if he can either capture Black's bishop and promote the f-pawn or simply promote his f-pawn. Capturing the g-pawn is not enough to win. If Black plays correctly, the Black bishop will never be captured, and as long as he maintains the king on f8, there is no way for White to drive out the king from f8 (no way to give check) and promote the f-pawn. So it is a draw.

I have attached here below the result from the endgame tablebases which have already evaluated this position. As you can see, all moves from White lead to a draw at best play. You can yourself enter this position and play with the tablebase on this website.


Why is the evaluation of the move h5 dependent on position of the bishop? [FEN ""]
[startply "50"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O b5 6. Bb3 Be7 7. Re1 d6 8. c3 O-O 9. h3 Na5 10. Bc2 c5 11. d4 Qc7 12. Nbd2 Nc6 13. d5 Nd8 14. a4 Ra7 15. Nf1 g6 16. Bh6 Re8 17. Ng3 Nd7 18. Nh2 f6 19. Be3 Nb6 20. axb5 axb5 21. Bd3 Bd7 22. Qd2 Nf7 23. Rxa7 Qxa7 24. Qe2 Qa6 25. Ng4 Kg7 26. Bc1 Na4 27. Bc2 Ra8 28. Qe3 c4 29. Rf1 Nc5 30. Nh6 Ng5 31. f4 exf4 32. Qxf4 Bxh3 33. Qh4 Bd7 34. e5 dxe5 35. Nh5 gxh5 36. Qxg5 fxg5 37. Rf7 Kxh6 38. Rxh7#

I have two questions.

1) Why was a4 played?

2) According to chess.com engine, after 26. Bd2, h5 is best, but after 26. Bc1 h5 is good. Why is that so?

...h5 is indeed good because it kicks the knight away from its current position (where it's a very dangerous piece)


A question about draw detection in chess engines Let us look at this position.
[FEN "4k3/8/8/p1p1p1p1/P1P1P1P1/8/8/4K3 w - - 0 1"]

This is obviously a draw. Analyzing this with the Stockfish engine says that it is a balanced position. However, Stockfish does not recognize that it is a draw.
Slightly rearranging the pawns, we receive a similar position that is an obvious draw.
[FEN "4k3/3p4/p1pPp3/P1P1P1p1/6P1/8/8/4K3 w - - 0 1"]

Here, Stockfish says that white has an advantage of +0.7.
Where does this miscalculation come from? I understand that draws in these positions cannot be detected from tablebases, as there are still too many pieces on the board. It seems that these special positions are called Pawn Rams or Blockages.
The chess programming article about Blockage Detection provides code for detecting blockages, but I do not understand how it works.
What are the underlying factors that make draw detection so hard from a computational point of view?

I actually did the experiment and will answer now. Three main factors go into the evaluation (as king safety doesn't play the slightest role): material, space, and movability.
The effect of space is rather high at +1.4.
[FEN "4k3/p1p1p1p1/P1P1P1P1/8/8/8/8/4K3 w - - 0 1"]

Any useless doubled pawn is about +0.7, giving +4.2.
[FEN "4k3/p1p1p1p1/P1P1P1P1/P1P1P1P1/8/8/8/4K3 w - - 0 1"]

Don't underestimate agility, we're already at +5.9.
[FEN "4k3/p1p1p1p1/P1P1P1P1/8/8/8/P1P1P1P1/4K3 w - - 0 1"]

You can give White a useless bishop and scratch the 10.0 but I stop here, although it would be a fun challenge for the highest evaluation in a dead drawn position But +99.0 seems to be Lichess/Stockfish cutoff. :-)


Pushing for Advantage with White in Correspondence chess I was viewing a top-level Correspondence chess game on ICCF between an International Master and a Senior International Master. They both had over 100 days on their clocks and they were in the following position with black to move:

r2r2k1/p1q2ppp/1p2pn2/8/2P5/1P3NP1/P3QP1P/3RR1K1 b - - 0 1

It seems that with so much time on their clocks and with the use of top-level engines and concrete analysis there is no way that white is pushing for anything here. I have also seen other games like this and my question is essentially why are they playing on in such positions?

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

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

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

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

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


Multimove variant rules with queen that does two moves in one I recall playing a multimove variant special rules chess game where one player (say black) has all the usual pieces, while the other player has just a queen that can do two moves in one.

So the queen can strike one of black's pieces and return to its position as if nothing happened -- "action at a distance"!

It was such that if one player Alice was a bit more skilled than another Bob, then Alice could beat Bob whether playing white or black.

Anybody know of rules like these?

A variant that I have played for a while years ago is: white has just the king and the four central pawns (cdef), but is allowed two moves per turn. All usual rules, including en passant and promotion, apply. Check and checkmate are defined via "the player that takes the opposing king wins". The variant is surprisingly balanced, with black probably at a slight advantage (but with a lot more possibilities for blunders).

Given that this variant is playable as it is, I suppose that anything involving a double-moving queen would be ridiculously overpowered for its side.

The white king in this variant can 'make a nearby piece disappear' as you mentioned. It takes a few games to understand the strategies for the two sides: against someone of comparable level who has never played this variant, a player with some experience can often ask them to pick a side, beat them, propose a rematch with sides switched, and then proceed to beat them again. :)


Alternatives to the FEN notation Apart from the FEN notation, are there other even more compact known chess-position notations? One that would of course also entail castling rights, and en passant possibilities.
One really missing bit in the FEN is the fact that it carries no information as to whether the position corresponds to a checkmate or check for that matter. Of course one can always put the position on the board and see if it's a checkmate or not, but it is not directly deducible from the notation. So such property would also be of importance in distinguishing between possible notations (apart from compactness etc.)

If it helps, this is asked for practicality and efficiency reasons in programming. Thanks for any suggestions.

Since you're talking about programming, you're presumably looking for a storage scheme more compact in computer memory space than FEN. Besides going out to research how it's done in large tablebases, two possibilities come to my mind immediately.

Normal FEN

For the sake of this discussion, "normal" FEN is just a typical text string represented with 1-byte (8-bit) characters. Let's look at a simplified worst case:

r1b1k1n1/1p1p1p1p/p1p1p1p1/1n1q1b1r/R1B1P1N1/1P1P1P1P/P1P1K1P1/1N1Q1B1R w KQkq e3 999 999

This isn't a valid FEN of course, but it's an effective upper bound on our complexity. There are eight characters per rank, plus seven slashes, five spaces, and thirteen additional characters make up the remaining fields. That's 89 characters, for a total size of 712 bits.

Compressed FEN

This version is just taking the a FEN representation and using some basic observations to reduce the number of bits required to store it. Here are our observations:

The slashes are unnecessary for machine storage; each rank must simply "add to 8". So we can eliminate slashes in our internal representation.
The remaining possible characters (in the first section) are: kK qQ rR bB nN pP 12345678. Distinction between 20 characters fits in five bits, so in our simplified worst case, we have five bits times eight files times eight ranks is 320 bits for the first part.
We don't need any spaces; again they're a convenience for humans. That saves us five characters.
"Who has the move" is one bit: White or Black.
Castling availability is four bits: available/unavailable for each of KQkq.
En passant is usually unavailable, and it can occupy a lot of space (six bits to represent all squares), so let's move it to the end and make it optional: if en passant bits are present, it's available, but if it's unavailable we just terminate the representation after the move & half-move bits to save space.
For simplicity, I'm just allocating ten bits for each of the move and half-move counters. This means that games represented in this format cannot exceed 1023 moves (half-moves since the last capture or pawn advance).

Our full format looks like this (in a simplified worst case with en passant available):

<position><whose move><castling><half moves><full moves><en passant>
 320 bits  1 bit       4 bits    10 bits     10 bits     6 bits

This gives us a total size of 351 bits in our impossible worst case, a little less than half the size of our starting point.

µFEN

If we abandon FEN altogether for the meat of the representation, we can slim it down a little further. Consider a single arbitrary square. That square can be empty, or it can have a piece on it. If it has a piece, it may be either white or black, and it may be a King, Queen, Rook, Bishop, Knight, or Pawn. That's a total of thirteen different states, which we can represent in four bits; something like this:

0000: empty square
0001: White Pawn
0010: White Knight
0011: White Bishop
0100: White Rook
0101: White Queen
0110: White King
0111: unused
1000: unused
1001: Black Pawn
1010: Black Knight
1011: Black Bishop
1100: Black Rook
1101: Black Queen
1110: Black King
1111: unused

Obviously there are some unused "partial bits", so this scheme could almost certainly be improved further by someone with more knowledge of compression techniques, or simply a more careful mapping of the different states. Also in practice, this might be larger than the Compressed FEN described above, since there's no compression of contiguous blank spaces. However, it does represent the whole board in a constant 256 bits (4 bits * 64 squares), which is a 20% improvement in the worst cases.

For simplicity, we'll just tag on the latter half of the Compressed FEN to complete the representation. So the format looks like this:

<position><whose move><castling><half moves><full moves><en passant>
 256 bits  1 bit       4 bits    10 bits     10 bits     6 bits

That gives us a worst-case space requirement of 287 bits. Not too bad!

Note 1: Remember, this is all just a worst-case analysis because I have a computer science background. Standard FEN usually performs much better than I have described it, since normal positions aren't the everyone-on-the-white-squares scenario I've used for comparisons here. So the percent improvements are likely a little lower than I've actually represented, but the trend probably still holds, at least for the compressed FEN representation. I'd be very interested if someone wanted to do a probabilistic average-case analysis for standard FEN (and by extension, the compressed version proposed above)!

Note 2: Remember that the speed tradeoffs for dealing with compressed formats may or may not be worth it for your applications! Depending on what language you're using and the level of control you have over individual bits, you may find that simple FEN is significantly faster to use, even if it requires more space!

Note 3: If you wanted to add a "check/checkmate/no-check" indicator to either of the new proposed notations, it's an extra two bits to represent the three additional states. Just toss it in before the en passant indicator.


Concerning a chess problem generating program Are there any programs that can generate a huge amount of different interesting chess problems? Are there any programs that can make a lot of retrograde analysis problems?

AFAIK, there aren't programs that generate chess problems On the other hand, there are several well known programs to verify chess problems (even with fairy chess conditions).
The main reason is that composing a good problem is kind of an art, the problem should not only be valid (in the sense that it is solvable etc.) but also esthetically pleasing. It also should be original, showing something new or fresh. These aspects are badly handled by computer programs upto now.


Why is Carlsen being praised for his tie-break play, when Caruana made several game-losing moves? I followed the three games live on chess24.es (for live commentary from GMs) and chess.com (for actual real time computer analysis).

As per my understanding:

Game 13 was mostly balanced until 19... Nb5? (GMs were expecting Nb7 if anything), and then after 34... Rc3? it was definitely over.
Game 14, Caruana was in a better position until 21. c5? which brought it back to balance, followed "shortly" after by 26. c7? which was definitely a losing move (live commentators went nuts here).
Game 15, there were no "obvious" errors (not that the GMs noticed on-air, at least), Caruana was even leading, but in the last half of the game the computer was marking several of Caruana's moves in red.

As far as I can tell, Carlsen didn't make any winning!! or distinctly good moves. Yes, he played great and made very few errors, but my feeling is that Caruana lost the game, more than Carlsen won it.

So, why is everybody praising Carlsen for his play? What moves or strategies did he apply in the tie-breakers that show how good he is?

Carlsen crushed it, made almost no mistakes whatsoever in rapid. It is as if he was playing at classical time controls.

Chess is about not making mistakes. If your opponent doesn't make mistakes then you're only going to get a draw even if you play like an engine.

He did play good moves as well. Example on move 37 the position is a draw but he gave himself winning chances with 37. Rc7!. Caruana now blunders with Kxe4 instead of playing Ra2+. Now Carlsen plays the accurate Re7+! instead of Rxg7? and obtains a winning position.


Free learning material I'm aware of several excellent youtube channels that are free and provide some great insight into the game, such as:

Chess Network
Online Chess Lessons
ChessFriends.com
Kings Crusher
Mato Jelic
YM Chess Master (IM Andrew Martin)

What are a few other good resources (free only please!) that a new player can find and how can I use them effectively to improve?

Here are some sites that I have found to be of great value:

chessopenings.com - NM Dereque Kelley explains openings very well.

The Chess Website - Excellent videos.

ChessVideos.tv - An abundant resource of top notch videos.

Exeter Chess Club coaching section - Excellent articles

ChessCafe columns (especially Dan Heisman's Novice Nook columns and Mark Dvoretsky's Instructor columns) - I can't recommend Dan Heisman enough,  his videos on ICC (not free) are excellent. Note: since the demise of the ChessCafe site these links point to the archive.org saved version.

50 Chess Games for Beginners - I stumbled upon this. Looks helpful, especially since the games are annotated.

Chess Visualization Training - Improve your visualization.


Is there a software where we can query historical games to find patterns without inputting the exact chess position? Suppose one wants to find:

A list of games where White/Black gave each other check more than 10 times.

A list of games where there were Black and White gave each other check in consecutive steps

A list of games where the king crossed the middle rank and still won

And so on.
Is there a software I can input these generic statements and find a list of games which have these conditions satisfied

As Brian mentioned, CQL (Chess Query Language) is the most capable tool for the job.  The current version of CQL at the time of this writing is 6.0.5 and the current website is http://www.gadycosteff.com/cql/.  The site provides lots of examples and comprehensive documentation.  Below are queries that will find games matching your three examples to give you an idea of what CQL looks like in practice.
More than 10 checks in a game
cql()
initial sort "total checks" find all check > 10

This will find all games where check was delivered (by both sides) more than 10 times in a game.  The matching games will be sorted in descending order by the number of checks delivered (the first game in the output will be the one with the most checks) and will contain a start-of-game comment with the number of checks that appeared in the game.  For example, here is a game from lichess.org that was found using this query with 81 checks.  By default, the query will also add a comment to each move that matching the find filter (i.e. each move that is a check).  The find filter is described in detail here.
Consecutive checks
The CQL website provides many examples.  The consecutive-checks.cql example finds games with 5 or more consecutive checks.  The query provided there is:
cql(input heijden.pgn)
sort "number of consecutive checks"
  line 5 100 nestban
    --> check+

The sort filter will again cause the games to be sorted by the number of most consecutive checks.  A comment will be inserted for each checking move in the longest line of checks for each matching game.  Documentation for the line filter used in this query is found here.
Winning side has King crossing middle rank
The following query will find all decisive games where the winning side's King moved to the opponent's side of the board at some point.  The first time the King crossed into enemy territory will be commented.  The query is written from the perspective of White (the filter result 1-0 means White won and Ka-h5-8 matches a position where the White king is present on ranks 5-8) but matches for both White and Black using the flipcolor query (the flipcolor query is described here).
cql()
initial
flipcolor { result 1-0 find Ka-h5-8 }


Can't decide on an opening for white My opening repertoire so far includes pretty much exclusively the French Defense as Black against e4, and that is about it. What does this indicate about what type of player I am?

Also what would be some good suggestions to play as White? I tried the King's Gambit a lot but it either is just not my style or maybe it requires more study than I have put in to get decent results with it.

I agree that 1.d4 and Queen's gambit are the best option from what you told about yourself.

In French, it's typical to have d4-d5 pawns in the center, a bad black white-squared bishop, space advantage for White and a plan based on c7-c5 for black. These points are also common in the Queen's gambit declined. I write from my own experience of playing these openings.

You might also search through a database and see which grandmaster's style fits you well, and copy their opening repertoire. Good luck!


Is it preferable to pass a FEN notation or list of moves to a chess engine? I am actually programming a chess UI and I'd like to communicate with a chess engine using UCI protocol. After reading the protocol specifications, I am not sure how to use the position command. For each move, is it better to pass to the chess engine a FEN notation of the actual state of the board or pass it the list of all moves that have been played since the beginning of the game?

It is preferable to pass a PGN because FEN is just a position with no move,  but a PGN is the whole game with moves.


...Nd8 vs ...Nb8 in the Bogo-Indian My question relates to lines which in general are covered by Avrukh (2015). However, Avrukh doesn't explain the phenomenon I noticed in the following lines. These lines are classed as Bogo-Indians, but I've kept the Catalan move order preferred by Avrukh.
[FEN "..."]
1. d4 Nf6 2. c4 e6 3. g3 Bb4+ 4. Bd2 Qe7 5. Nf3 Nc6 6. Nc3 Bxc3 7. Bxc3 Ne4 8. Rc1 d6 9. d5 Nxc3 10. Rxc3

Here out of 271 games in my database there are 160 with 10...Nb8 and 106 with 10...Nd8.
[FEN "..."]
1. d4 Nf6 2. c4 e6 3. g3 Bb4+ 4. Bd2 Qe7 5. Nf3 Nc6 6. Nc3 Bxc3 7. Bxc3 Ne4 8. Rc1 O-O 9. Bg2 d6 10. d5

Here out of 768 games there are 264 with 10...Nd8 and 69 with 10...Nb8. However, the most popular move (434 games) is 10...Nxc3, which leads us to the following position
[FEN "..."]
1. d4 Nf6 2. c4 e6 3. g3 Bb4+ 4. Bd2 Qe7 5. Nf3 Nc6 6. Nc3 Bxc3 7. Bxc3 Ne4 8. Rc1 O-O 9. Bg2 d6 10. d5 Nxc3 11. Rxc3

Now there are 535 games, of which 370 go 11...Nb8 and 146 go 11...Nd8.
Why is there a distinct preference for ...Nb8 in the first and third positions, and a distinct preference for ...Nd8 in the second position?
Avrukh, Boris (2015). Grandmaster Repertoire A1 – The Catalan. Quality Chess.

While the king knight remains on the board with options to move to c5 or f6,  ....Nb8-d7 is an overlap.


I provided water bottle to my opponent, he drank it then lost on time due to the need of using bathroom. Is this unethical? Many years ago, I was playing in a chess tournament. We had been at the board for at least three hours. My opponent had spent the entire time at the board trying to find good moves. I had the better position and plenty of time on my clock. My opponent had less then 10 minutes on his clock. I also taken a couple of bathroom breaks.
The tournament provided free bottles of water. I got up from the board and got two bottles of water. I started to drink one and placed the other bottle near him. Neither one of us said anything to each other. He opened his bottle and started to drink it. About 10 minutes after drinking the water, my opponent needed to use the bathroom which he did. While he was gone from the board, he went over on the clock.
Did I do anything unethical?

No, what you did is what is known as a gambit. You offered your opponent material (in this case a water bottle), which he accepted. This would be considered a blunder on his part, since although it gave him a temporary hydration advantage, it ended up costing him time due to the uncomfortable situation it caused for his bladder, which needed to be resolved. If he had instead declined the gambit, he may have won, but such is the way of the game.


What is black trying to accomplish when playing Bb4 after Nc3 in the opening? This happens sometimes when you're playing a person, more often when playing the computer it seems. The lichess Android app for e.g., on the easiest setting, always follows Nc3 this way (usually following on the first variation below).

[FEN ""]
1. e4 e5 2. Nc3 Bb4 3. a3 ( 3... Bxc3 4. bxc3 Nf6 5. Rb1) (3... Ba5 4. b4 Bb6)

Every time I see this played I wonder what black is trying to gain here. He either ends exchanging the bishop for my knight (and giving my rook a good open file) or locking his bishop in one corner, neither seems particularly useful.

Am I missing something?

It is indeed a little silly to play ...Bb4 on move 2 here. That said, it often gets played a little later, and the main idea is to pin the knight on c3 (after the d-pawn has moved), so that it no longer protects the pawn on e4, which can now be attacked by a knight on f6, say.

In the particular line you gave, by the way, the bishop is doing just fine on b6. You spent time kicking it to a place where it's aiming right at the weak pawn on f2 and beyond to your king on g1 once you castle.


Uncovering the Accelerated Dragon opening I had previously heard and seen in commentaries about the Dragon opening where black plays an early g6 to develop the bishop on g7 after the typical open Sicilian starting moves c5 cxd d6. But how does the Accelerated Dragon differ from the usual Dragon and what aspect of it is being accelerated?

A short explanation of the naming and summary of the underlying opening idea would really be helpful.

Dragon

The opening is named after the Draco (Latin for dragon) constellation because if you remove all the pieces and just look at black's pawn structure with the  pawns on g6 and d6 it looks like the dragon constellation as shown below (image source):

Accelerated

Unlike the mainline Dragon Sicilian where d6 is a key early move (1.e4 c5 2.Nf3 d6...), even though later it might still be pushed to d5, the accelerated version attempts to play d7-d5 in one go, without the inclusion of an early d6 move, and hence the name accelerated Dragon.

Here's an important move order that really typifies the accelerated Dragon, where everything black has set out to do has been achieved: safe king, healthy development, a successful early d5 push to undermine white's center, powerful bishop on the long diagonal, active play in the center and on the queenside. I highly encourage you to closely study the 3 variations that can result from either of the 3 ways white can capture the pawn on d5 on the next move.

 [Title "Accelerated Dragon, typical position"]
 [fen ""]
 [StartFlipped "1"]

 1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 g6 5. Nc3 Bg7 6. Be3 Nf6 7. Bc4 O-O 8. Bb3 a5 9. f3 d5

Basic plan for black:

In short, having neutralized white's central d4 pawn for our c7 pawn, black fianchettoes their kingside bishop and exerts pressure on the long diagonal from the get-go, unlike most other Sicilian variations where the dark squared bishop stands quite defensively. Additionally, the fianchetto structure is a good defensive fortress for the king.

Moreover, black's kept both central pawns (e and d) and in the future they can potentially make a better claim at central control as the central pawns are 2 for 1 in favour of black. Considering that white's only remaining central control lies in their e4 pawn, with constant threats of e5 kicking our knight to a less ideal  post, black's constantly playing towards making the d7-d5 break happen as early as possible, neutralizing white's only  central foothold.


How do you convert a scid database into a pgn database? So I got a big scid database and ScidvsMac. I would like to convert the complete database into a pgn database. So far I have only found out how to convert single games into pgn, something I'm not keen on doing a million times.

So how do you do this with scid? And if scid doesn't have this functionality, is it possible to maybe do it game by game via command line?

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


Why is an isolated queen pawn so special? Various articles and books mention the following advantages of having an isolani:

Better development
Outposts on e5 and c5
Constrained Black position

What I don't understand is how are the above mentioned advantages specific to isolani? Any side which gains centre control will get these advantages, right?

So back to the question, what makes isolani special? If I have an isolated pawn at some other file say c-file or e-file, the same rules will apply right? I'll still get the same advantages while having the disadvantage of being isolated.

It is mainly so special because it can arise from many different openings, both open and closed, e.g. the Queen's Gambit, Nimzo-Indian, Caro-Kann and the Alapin variation of the Sicilian. It is simply much more common than a mirrored situation with an isolated pawn on e4, which would require exchanging the white f-pawn, which often stays on f2 to protect the king. In general, an early isolated pawn on the n-file requires an early n4 move by White and n5 by Black, followed by undermining pawn moves in the adjacent files. Those are most likely to happen on c-, d- and e- files.

An IKP (Isolated King's Pawn – an isolani is often called an IQP) would give the same advantages, but in addition:

it would be harder to defend than an IQP
assuming kingside castling, the half-open f-line would give White even more attacking chances, at the cost of being more exposed as well

A isolated c-pawn is even rarer, and has less influence on the center than a d- or e-pawn. All other things being equal, this is definitely a disadvantage for the side having an isolated pawn.

Hanging pawns are another commonly occurring structure where (potentially) weak pawns have compensation in the form of center control and space advantage.


What are some good podcasts to listen to? I'm an intermediate player, and I practice chess tactics and play regularly. I'm looking for a good podcast or two to listen too during my day. I don't care if its a podcast that discusses chess news, tactics, or does analysis of games, I just need it to hold my attention for a while. Preferably something available on android or pc.

Thanks

The Full English Breakfast by Stephen Gordon, Laurence Trent and Macauley Peterson was always fun. It has been discontinued 2 years ago but it might still be worth a look.


How to show captured pieces in Arena? I'm using Arena 3.5 on Windows. When playing, I want to see a list of the captured pieces beside the board in Arena. How do I do that?

There is a checkbox for it:-

Options | Appearance | View tab | Material difference

You may need to make the opening classification panel taller and then use the splitter on its left to see the material difference panel.


In the Berlin Defense(ruy lopez), why has the Ne7 Ng6 plan gone out of fashion? It seems that after 9. h3 or 9. Nc3, black usually plays Ke8, Bd7, h6, and sometimes Ne7. My question is: why isn't 9... Ne7 played more often, with the plan of putting the Knight on g6?

Situation:

[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5. d4 Nd6 6. Bxc6 dxc6 7. dxe5 Nf5 8. Qxd8+ Kxd8

One of the reasons could be that the knight on f5 is already developed. Probably it doesn't appeal to many players to spend 2 tempi to reposition the knight, while black is already slightly behind in development.

Futhermore, many alternative setups are possible and perfectly playable: Ke8, Bd7 and Kc8, etc...

However, it seems that an early Ne7 recently regained some of its popularity:

So - Kramnik
Maze - Smith
Caruana - Dominguez
Caruana - Carlsen
Nakamura - Topalov


Is there a collection of chess images in public domain? I am looking for images of chess players, pieces, as well as any other graphics related to chess - public domain only.

http://www.chess.com/forum/view/general/greatest-chess-photos

Has probably some of the most epic pictures in chess history


Why is g5 much better than gxh5 in this position of Anand? To me, Anand's 13. g5 instead of 13. gxh5 was very surprising.
[Title "Vishwanathan Anand vs Nafiz Ediz İlhan, chess24.com"]

[FEN ""]

1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. d4 O-O 6. h3 e5 7. d5 a5 8. g4 Nfd7 9. Be3 Na6 10. Rg1 Ndc5 11. h4 Kh8 12. h5 gxh5 13. g5 Bg4 14. Rxg4 hxg4 15. Nh4 Qd7 16. Be2 g3 17. Bg4 Qe7 18. Bf5 gxf2+ 19. Kxf2 f6 20. Qh5 Bh6 21. Qxh6 Nd3+ 22. Ke2 fxg5 23. Ng6+ 1-0

My reasons are:

With rook on g1, 13. gxh5 gives it a direct open file against the king.
13. g5 allowed 13... Bg4, necessitating 14. Rxg4, an exchange sacrifice for the attack to continue.
The fundamental idea of any pawn storm, such as that attempted by Anand, is to exchange pawns in front of the king.

It is clear that Anand considers gxh5, but finds it so bad that he says "I might have been a bit careless here"!
This completely took me by surprise.
Why is 13. gxh5 so bad? And 13. g5 much better?

With rook on g1, 13. gxh5 gives it a direct open file against the king.

Wrong! The black king is not on the g file. It is on the h file and the rook on f8 is ready, if required, to come to g8 and fight for the open file.

g5 allowed 13... Bg4, necessitating 14. Rxg4, an exchange sacrifice for the attack to continue.

Again, wrong. 13... Bg5 14 Rxg4 hxg4 really does open the file the black king is on, the h file. "allowed" is wrong and so is "necessitating". This sequence accelerates the attack. Without using an engine, 13... f5 looks to be better for black than Bg5, or at least less bad.

The fundamental idea of any pawn storm, such as that attempted by Anand, is to exchange pawns in front of the king.

Which is what happened in the game (white got rid of his h pawn, opening up the h file against the black king, and got rid of the black g pawn which was defending h5) with the bonus that white's g pawn was retained as a threat.

Why is 13. gxh5 so bad?

It blocks the h file (the file the black king is on) with a white pawn which white can't remove.


Elements to take into account when evaluating 'board strength' As part of a demo for a rules engine I'm dreaming up, I'd like to do an evaluation of a chess board that communicates each side's general strength at that point in time.  Advanced things like predicting moves or establishing mate patterns are way beyond the scope of this idea; I only need to think about what's in front of me for now!

I also do not need to establish precisely how to reduce board strength to a number; that will be a lot of tinkering, this way and that, to find something that seems reasonable.  For now I just need to figure out the top, say, 3 elements to deciding how strong or weak someone's position is on the board.

My current thought is, in general order of importance:

Material (in pawns, so rook = 5, knight = 3 etc)
Open attack paths on the center of the board (critical area, goes to development)
Total attackable squares (development)

Am I missing a particularly important element in this evaluation?  Am I attempting to measure it wrong?

It depends on how much accuracy you want to put in, but to have a precise strength, it needs to be able to build a tree of possibilities and look for moves ahead.

Just imagine a hypothetical case where one have tons of material, already developed everything, castled, some pawns close to be promoted BUT without being able to do anything to prevent getting mated. There is no way to give a correct read no matter how much elements you take into account without some alpha-beta searches.

More information can be found in this article.

But I suppose that is too difficult to implement, some easier starting points to do are:

Some things that chess engines do is to recognize end/middle
game patterns and also get help from opening databases.
You can also look for poorly placed pieces like bishops trapped by
own pieces or the king being too exposed.
Check for castling ability and how easy is to perform that (e.g pieces in the way or attacked squares)
At the very endgame, be familiar with the terms "wrong bishop", "opposition" and "rook pawn", etc. (those are often decisive and should be easy to determine wins, loses and draws)


White to play and checkmate in two moves It’s White to play and checkmate in two moves.

This puzzle was created by Frank Healey, and published in 5 Family Herald on 7/17/1858.

7R/1B1N4/8/3r4/1K2k3/8/5Q2/8 w - - 0 1

Use the fact that the rook is pinned, and that the king has few squares left;
I'm thinking that 1.Rd8 Kd3 (only possible move) 2.Nc5# should be the solution.

[White "NN"]
[Black "NN"]
[FEN "7R/1B1N4/8/3r4/1K2k3/8/5Q2/8 w - - 0 1"]

1.Rd8 Kd3 2.Nc5#


Can tactics be reduced to a finite number of simple patterns that can be learned? I realise that there are a finite number of tactical techniques such as forks and skewers and pins but I find them hard to identify in everyday play. I have started using chess.com's tactics trainer and am gradually making progress. However I think that this is ultimately a pattern recognition problem.

So my question is whether it is possible to reduce all of the tactical tricks to a finite set of graphical images that I could stare at and memorise in the same way children learn their letters. I think that this may get my brain to identify these opportunities more quickly when they arise on a chess board.

I would say that, indeed, the vast majority of tactics falls into some kind of pattern and there are a number of them but not too many.

In my opinion there are two issues that you need to improve in order to improve tactics in your games.  First, you need to know the basic patterns, that is you have to know how they look like and what is the main idea in exploiting them.  Often the basic ideas of the pattern cannot be applied out of the box and you will need to find the right moves to actually implement the combination.  The second issue is that, of course, you have to spot these patterns on the board and exploit them.

For picking up the patterns a tactics book that presents problems grouped by patterns, together with some explanations how to exploit them, is very useful.  E.g. "Tune Your Chess Tactics Antenna".  To facilitate the second step, such books often have mixed exercises at the end, where you are not told what the pattern is you should find, but then almost any tactics book with mixed problems will be okay.


Is there a forced win in CastleChess? Is there a forced win for White or Black in the chess variant CastleChess? The rules are explained in this post on an obscure blog named “Cinquante signes”, although it is originally from chessvariants.com.
The rules are the same as the orthodox ones, but with two big differences.

White wins via checkmate or if Black can no longer castle queenside. If either the Black king or queenside rook move, of if the rook is captured, Black can no longer preform queenside castling, and thus they lose.

Black can win by giving mate or castling queenside.

The devil is in the details, and there are some questions on the blog that help give insight into whether or not it can be solved.

Q.(b): Is it easy for Black to castle long (and immediately win the game)?

Well, if White is not prudent, yes -in theory, 5 moves are enough for Black to win.

Q. (c): Are draws still possible?

Oh yes, if it's White turn to play for instance, and White is (a) not in Check (b) in check if it moves, the game is a draw (as in orthodox chess).

Q. (e): Do you have any strategic advice?

Yes-there are weaknesses in Black's position. White could focus on: the pawns a7, b7 and f7 for instance.

Q (f): And what about Black's defense?

This position is solid-and, in a few moves, Black might be able to castle long and win: put all Black pieces on their starting square, except 3 — the e7 pawn is on e6; the b8 Knight is on c6; the f8 Bishop is on b6.

A million years ago, a friend  showed a very simple variant: One random  pawn on each side is marked, and if it's captured (by a move that isn't checkmate), the capturing side loses.
The Danish Gambit was popular that night,  but otherwise,  people were flinging pawns around,  planning to win with the variant rule  (I guess you could call it a truly poisoned pawn). I said to my friends that I thought the right strategy was no strategy: Just play chess, and try to win the chess game. You'll lose a few games by chance,  but you'll also win a few.
Was I right or wrong, I won't say.  Maybe you'll try that variant yourself to test both ways of handling it.
I'm a very big fan of the 3 Check variant (so is Karpov). That game messes with your mind. The nitwits who try to win by delivering a third check run out of sacrificial fuel, while playing normally is dangerous, because the variant rule is often just a matter of tactics (that is, some combination that makes one or two checks while sufficiently exposing the king for more).
I gave this castle chess thing some thought,  and I was amused by the different winning conditions.  White is likely to go nuts in search of a short combination to prevent castling, while Black (I think) should play normally but with a view toward O-O-O.
Is there a forced win for White? I doubt it, and after that bit of thought,  I began to favor Black.


Looking for a simple GUI for variants of chess I am currently coding an engine for a variant of chess called Monster Chess. I was wondering if there a GUI existed that would simply take pieces from a square to another (eg e4 to e5) without considering the legality of the move or whose turn it was, since in Monster Chess white gets two plies for every ply black gets, and white can temporarily move into check.

The chessboard editor at https://www.apronus.com/chess/pgnviewer/ has two modes selected by radio buttons: "position setup" and "legal moves only". In position setup you can do anything on the board including adding or removing chessmen.


What's with the Petrov? The Petrov or Russian opening is seldom seen these days:

[fen ""]

1. e4 e5 2. Nf3 Nf6

Why? Is it fully refuted? Or merely uncomfortable for Black?

There is nothing wrong with the Petroff and it is still used regularly at the highest levels. If it is less popular than it used to be (and I'd have to check the data before claiming that), then that would likely be because it is usually played when Black is trying to make a draw, and these days the Berlin variation of the Ruy Lopez is the most popular way to try to achieve a draw against 1.e4.


How to automatically evaluate a player's performance in a game? Suppose I have a completed game. I don't have Elo ratings of the players. My purpose is to evaluate a player's performance in the game based solely on his moves. Can this can be done automatically using a chess program?

The result can be his approximate Elo rating, or just some value indicating his strength or error rate.

If it helps, a database of the player's games can be given. Again, with no Elo ratings.

My motivation is simple. I play chess over the internet and would like to automatically track my progress, based on the games themselves, not on the rating on the sites. I'm a (upper)-beginner level.

A simple solution is to annotate the game using any computer engine and track number of ?!, ? and ?? marks. However, it's not very accurate, and I'd like to get more ideas :)

The Site ratings at slow time controls can be quite reliable for servers where strong players congregate (ICC, FICS to name a few) as the ratings VERY closely reflect your true playing strength if you've played enough games. For very standardized rating systems such as USCF and FIDE/ELO, you will notice that the different rating classes tend to point to the types of mistakes those players are still making. NM Dan Heisman's Improving Chess Thinker does an excellent job discussing the types of errors players make across the rating classes.

Have you tried the many self-test books out there?  Igor Khmelnitsky's Chess Rating Exam and  Danny Kopec's Test, Evaluate and Improve your chess are excellent books that allow you to track your progress by seeing how you perform against graded test positions.

Your compare-my-moves-with-an-engine approach is another way to do this but once again, the ??/? moves are really only indicating tactical errors, not strategic or positional or even behavioral or time-management mistakes you might be making.

That's why playing slow time-control OTB/online games against equal-to-stronger opposition and getting them reviewed + critiqued by stronger players is an efficient way to improve. Your mistakes in every category (tactics, knowledge, thought process, time management etc.) get highlighted and you can simply measure progress in terms of the mistakes you've stopped making.

Though one fun variant you can try with an engine at home: Why not extend your engine-evaluation method to visually observe a player's quality/performance via evaluation graphs?  In other words, take engine evaluation scores per move and plot them (some free software like SCID does this for you) over the moves.

For example: Two rank beginners would have a game that looks like:

Notice how jagged these are. Both sides make many terrible mistakes (slopes of the spikes!) and also how often they fail to exploit the other person's terrible mistakes.

The spikes are always fun to look at :

Two intermediate (USCF 1400-1600) players might have games that look like:

It does look jagged, but notice how the y-axis (engine evaluation) is way smaller ... indicating that these players are more seasoned and play higher quality chess than the novices.

For a final comparison, a 1911 Grandmaster game would look like this:

No comments necessary here :)  These guys really don't make many mistakes, do they?

If you could devise your own heuristic for mapping the slopes + scale of an evaluation graph to  player skill/performance, perhaps this is one way to go? :)


Why is Rashid Nezhmetdinov not as popular/known as Mikhail Tal? I was looking at some games between of Rashid Nezhmetdinov and noticed he doesn't seem to be as popular (I don't know if this is the best word) or as well-known as Mikhail Tal.  After reading some of the things said about him, you would think this is not the case:

  "Nobody sees combinations like Rashid Nezhmetdinov." Mikhail Botvinnik

  Nezhmetdinov is "the greatest master of the initiative." Lev
  Polugaevsky

  "His games reveal the beauty of chess and make you love in
  chess not so much the points and high placings, but the wonderful
  harmony and elegance of this particular world." Mikhail Tal

  "Rashid
  Nezhmetdinov is a virtuoso of combinational chess." David Bronstein

Here is his most celebrated brilliancy vs Lev Polugaevsky, featuring a stunning queen sacrifice:

[FEN ""]
1.d4 Nf6 2.c4 d6 3.Nc3 e5 4.e4 exd4 5.Qxd4 Nc6 6.Qd2 g6 7.b3 Bg7 8.Bb2 O-O 9.Bd3 Ng4 10.Nge2 Qh4 11.Ng3 Nge5 12.O-O f5 13.f3 Bh6 14.Qd1 f4 15.Nge2 g5 16.Nd5 g4 17.g3 fxg3 18.hxg3 Qh3 19.f4 Be6 20.Bc2 Rf7 21.Kf2 Qh2+ 22.Ke3 Bxd5 23.cxd5 Nb4 24.Rh1 Rxf4!! 25.Rxh2 Rf3+ 26.Kd4 Bg7!! 27...b5! and 28...Nec6#. 27.a4 c5+ 28.dxc6 bxc6 29.Bd3 Nexd3+ 30.Kc4 d5+ 31.exd5 cxd5+ 32.Kb5 Rb8+ 33.Ka5 Nc6+ 0-1

Regarding the above game, Polugaevsky is quoted as saying, "I must have beaten Rashid a dozen times. But that one loss was so good I would have traded them all to be on the other side of the board."

Probably because he never made it to world champion, And Mikhail Tal did. Another great player that is not as popular as he deserves to be was Akiba Rubinstein


Why can't I place the rook in front of the queen? I was playing chess this afternoon on my mac, as human vs computer. In the position below:

[FEN "6k1/5pp1/2p3bp/pqP1P3/2R3P1/PPQ5/4K3/8 w - - 0 24"]

I tried to place the Rook in front of Black's Queen (b4), but this action was blocked and the Rook remained in the same place. Later I completed the game by making another move.

Why is this so? Why can't I place the Rook in front of Black's Queen? Please explain this.

The Rook on c4 is pinned against the your King by the black Queen. Thus you can't move it without exposing your King to the Queen's wrath.


How to play vs 1.e4 e5 2.Nf3 Nc6 3.d4 Nxd4? How to play vs 1.e4 e5 2.Nf3 Nc6 3.d4 Nxd4? Assuming that we want to recapture, is it better to take the d4 Knight or the e5 Pawn?

After 1.e4 e5 2.Nf3 Nc6 3.d4 Nxd4, both 4.Nxd4 and 4.Nxe5 seem to lead to an advantage for white. However, it's hard to tell which of the two options is best. Therefore it's a matter of taste.

4.Nxd4 exd4 5.Qxd4 transposes to the Scottish main line, where black played the inferior 4....Nxd4. This option is the easiest for white: white stays in his repertoire after 3....exd4, unless he wanted to play a Scottish gambit line, e.g. 4.Bc4 or 4.c3.

However, 4.Nxe5 also yields an advantage for white. After 4....Nc6 5.Nxc6, white has an extra tempo compared to 3....exd4 4.Nxd4 Nf6 5.Nxc6. Instead, black can retreat with 4....Ne6. According to the Game Database of ChessTempo, 5.Bc4 is the most popular reply, but 5.g3 seems an interesting alternative.

Edit: It's important to mention that, after 4.Nxe5, 4....Bc5 is a mistake. One refutation is 5.Nxf7, given by Evargalo, as white regains the piece after 5....Kxf7 6.Qh5+. Instead, black should complicate matters by 5....Qe7 or 5....Qh4. According to Stockfish 9, play should continue with 6.Nxh8 Qxe4+ 7.Be3 Nxc2+ 8.Kd2. Another refutation is the natural 5.Be3. Once again the Nxf7-idea comes into play: 5....Ne6 6.Bxc5 Nxc5 7.Nxf7 Kxf7 8.Qh5+. Black can avoid material losses by 5....Qh4, as 6.Bxd4 is answered by 6....Qxe4+. Nevertheless, white obtains a clear advantage after 6.Nc3 Ne6 7.g3 Qf6 8.Nc4.

      [StartPly "5"]

      [FEN ""]
      1.e4 e5 2.Nf3 Nc6 3.d4 Nxd4 (3...exd4 4.Nxd4 (4.c3)(4.Bc4) Nxd4 (4...Nf6 5.Nxc6) 5.Qxd4) 4.Nxe5 (4.Nxd4 exd4 5.Qxd4) Bc5? (4...Nc6 5.Nxc6)(4...Ne6 5.Bc4 (5.g3)) 5.Be3 (5.Nxf7 Qe7 (5...Kxf7 6.Qh5+)(5...Qh4 6.Nxh8 Qxe4+) 6.Nxh8 Qxe4+ 7.Be3 Nxc2+ 8.Kd2 Bxe3+ 9.fxe3 Nxa1 10.Nc3) Qh4 (5...Ne6 6.Bxc5 Nxc5 7.Nxf7 Kxf7 8.Qh5+) 6.Nc3 (6.Bxd4 Qxe4+) Ne6 7.g3 Qf6 8.Nc4


What is a pawn break? I did some research (google), but it still unclear to me on exactly what a pawn break is.  I was reading this question: The theory of pawn breaks about the theory of pawn breaks, but before I could understand this, it would be helpful if I actually knew what a pawn break is.  If someone can explain it simply and have some diagram(s), that would be best.

A pawn break is a pawn move designed to free the player's position.
Generally speaking, a pawn move is only called a pawn break when the moving pawn is on a file adjacent to two enemy pawns facing each other, and the pawn moves forward to the same rank as the player's other pawn.
Since a picture is worth a thousand words...
[FEN "8/8/8/4p3/3pP3/3P4/2P2P2/8 w - - 0 1"]

White can play either 1. c3 or 1. f4 and these moves would be considered pawn breaks because they attack a black pawn that is blocking a white pawn (the d and e pawns respectively).
1. f3, however, is NOT a pawn break because it does not attack an enemy pawn.  Similarly 1. c4 is not a pawn break, even though black could capture the pawn with 1... dxc3 e.p. and get to the same resulting position because again, it does not attack a black pawn.


How do I make my opening reportorie stronger, specifically my Grand Prix Attack against high level competition? I saw the DVD Killer Grand Prix Attack from GM Gawain Jones. This helped a lot. However, I have some trouble with some concepts against 2 ...e6 lines. According to the DVD the second plan of the Grand Prix Attack is to play Bb5 and capture the Nc6 to give Black double c pawns then attack the double pawns in a positional way. However, I sometimes heard you have to transition to Closed Sicilian or Open. Here is an example were I'm unsure.

e4 c5
Nc3 e6
f4 Nc6
Nf3 d6
Bb5 Nge7
o-o g6
d3

Would it better to play Bb5 earlier to go for the double pawn plan or 5. Bb5 here is better such as this game was played? Would 7. d4 be better than 7. d3?

What are further resources to study the Grand Prix Attack seriously?

As resource:

Please check Lawrence Trent's analysis from White's perspective and Andrew Martin's's from Black's perspective.

About line:

I don't find it correct to say anything about this line without studying state-of-the-art. So, you better check experts analyses for suggestions.


Is it possible to fully analyse, at least some openings of chess? While, I'm fully aware that the number of chess moves exceeds the number of atoms in the universe greatly, and so solving it is a problem that falls in NP, I was wondering if certain variations of it can be solved.

I know that chess itself can't be solved.* But, is it possible to solve at least a few openings ? What I mean is, is it possible for computers to definitely say "For this variation of the Sicilian Defense, White is winning." or "For this variation of the Queen's Gambit, Black is winning." Are there special cases where it is possible to say exactly which side is winning after 7-8 moves?
(* - Strictly speaking, it has not been proven that chess cannot be solved. It cannot be solved by a brute force search of the game-tree, because such a graph is too large. But not all algorithms have been excluded in their ability to solve chess).

The moment we knew that a variation would be winning for either White or Black, the other side would never go for that variation. E.g. after 1. g4 e5, White will never play 2. f3 because we know that variation is winning for Black.

But there are some openings which have been analyzed to a draw by repetition of moves, even before the computer era, e.g. the Greco variation of the main line (Giuoco Piano) of the Italian game:

[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4 6. cxd4 Bb4+ 7. Nc3 Nxe4 8. O-O Bxc3 9. d5 Bf6 10. Re1 Ne7 11. Rxe4 d6 12. Bg5 Bxg5 13. Nxg5 O-O 14. Nxh7 Kxh7 15. Qh5+ Kg8 16. Rh4 f5 17. Qh7+ Kf7 18. Rh6 Rg8 19. Re1 Qf8 20. Bb5 Rh8 21. Qxh8 gxh6 22. Qh7+ Kf6 23. Rxe7 Qxe7 24. Qxh6+ Kf7 25. Qh7+

Almost all deviations after move 8 or so have been proven either to draw as well, or to lead to a worse position.


Bronstein timing vs. Simple Delay, Is there a formal definition of Bronstein Timing that specifies whether the increment should be added initially? There seems to be some controversy on whether there is really any practical difference between Bronstein timing and Simple Delay timing.  By "Bronstein" and "Simple Delay" I'm referring to the timing methods described in this Wikipedia Article

Now I think the fact that the two timing methods are functionally equivalent is proven quite convincingly in this YouTube video. Note that the DGT clock shown using Bronstein timing starts by adding the delay to the initial time before counting down and that is an important factor in making the two timing systems equivalent.  Note that the Wikipedia definition I linked to earlier doesn't make any mention of whether the delay interval should be added to the time at start.

I've also noticed that other clocks that implement Bronstein timing don't automatically add the interval time at the start. For example, the Garde clock shown in this YouTube video.  (Note, jump to 2:37 to see the clock started)

In the case of a clock like that, I believe the two timing systems aren't functionally equivalent in that the Bronstein timer would always run out sooner by the amount of the delay.  And in the case of a secondary time control, that would accumulate so that it would be shorter by 2xDelay.

So here is my question, I can't find any definitions of Bronstein timing that specify whether the delay should be added to the start time as DGT has implemented it and I can't find the text of David Bronstein's original proposal of this timing method to see if it specified how the start time should be handled.  To me the DGT way seems more correct, but if it isn't really specified then I guess both clocks could be considered correct as it is ambiguous how it should be handled.  I also couldn't find a FIDE rule that specifies how Bronstein timing should work.

So does anyone know of a formal specification that addresses the starting time issue?

Also, If anyone has experience with other clocks that implement Bronstein timing other than the DGT and Garde clocks I mentioned, do most clocks add the delay from the start like the DGT or just start counting from the set time like the Garde?

The Fide Laws of Chess state the following:

6.2. b. The time saved by a player during one period is added to his time available for the next period, except in the ‘time delay’ mode.
In the time delay mode both players receive an allotted ‘main thinking time’. Each player also receives a ‘fixed extra time’ with every move. The countdown of the main time only commences after the fixed time has expired. Provided the player stops his clock before the expiration of the fixed time, the main thinking time does not change, irrespective of the proportion of the fixed time used.

I'm under the impression that the literal interpretation is the correct one, and the delay should be added to the start time.
Technically, The Youtube video does not show whether the first 5 seconds of the first move are the delay (making the time control essentially 79 minutes 55 seconds for 30 moves etc. with delay starting from the first move) or not (the delay in the first move is completely skipped).
In addition, the video does not show what happens when the 30 move mark is reached, but the clock seems to be counting moves, and I assume it will add the extra time automatically, and I don't see any reason it won't also add the delay at the end of the 30th move.

While this was not your question, I think it's worth mentioning: The only other section related to this topic I could find in the Fide Handbook is in the section "Standards of Chess Equipment and tournament venue for FIDE Tournaments":

5.1. (b) The display at all times should show the time available to complete a player’s next move.

so it appears to me that in terms of the Fide rules, the correct method of showing time is the Bronstein method, as opposed to the delay method.


Does SCID have a function that allows to print a single game with variations as ECO table? Other major chess database programs allow this, but I am curious if SCID has this "print as repertoire" function. Opening report in SCID creates an ECO table from multiple games, but I'd like to instead use a single game with sub-variations as input.

First of all, I do not know if trying the feature Opening Report on a single game (or a database composed of a single game) would show the variations in the ECO tree. If you have not tried it, this would be my first step.

I also don't know if the ECO table can be directly printed as on ChessBase (it certainly is a great feature), but what you can do, albeit being a bit more of work, is to make a SCID database rewriting all the variations as whole (unfinished) games, and then use Opening Report to get the desired ECO tables.

What I mean by this is that if I have a game that goes:

    [FEN ""]
    1. e4 e5 2. Bc4 (2. Nf3 Nc6 3. Bc4) Nc6 3. Qh5 Nf6 4. Qxf7#

Then the variation shall be included in the database and this game would be split into two, the main line and the variation, when being rewritten. When using Opening Report on this variation filled database, you will certainly obtain the ECO tables (and more).

This should not be extremely difficult and hopefully not long. I suggest you take a look at this video, as here the theme of easily including and saving variations in a game is a bit discussed (although the main purpose of the video is to use SCID to develop an opening repertoire).


Polish Opening development The main idea of this opening is to get a mass of center pawns, for less development. How can White get his pieces out before Black can develop too many pieces?

The line that you refer to is probably 1.b4 e5 2.Bb2 Bxb4 3. Bxe5 Nf6.. I recall some early opening books saying that this was a bad defence because it surrendered a center pawn. The more modern view is that Black does get a very fast development in this line which is quite dangerous. I gave up the Polish when this started to become well-known. Until then I had good results. Often I got something like a reversed Sicilian with a very useful move thrown in.
I have not kept up with recent developments but there is an article in New in Chess
yearbook 132(2019) which is where I would go to catch up.


Does "juicer" mean bishop? I watch many videos of Hikaru Nakamura and I hear very often the term "juicer." Is it a slang word to refer to the bishop? Also, know the queen as a lady or girl.

Does “juicer” mean bishop?

This YouTube video of Hikaru playing the Beth Harmon bot gives some clues.
First, at 3:06 he says "I think I can just throw in a juicer check" and indicates a bishop check with arrows on the board. This suggests that juicer does mean bishop for him.
However at 3:33 he says "I don't understand. I'm just up a juicer, aren't I?" when he is up a knight.
Then at 3:50 he says "Let's block the juicer, no nonsense." as he blocks a pawn.
Finally at 7:00 he says "A juicer is just whatever you want it to be. The juice is the juice"


Dumb question, but what are some good chess resources to learn from? I have looked in a lot of places, but I can't find good places to learn chess. I am at the stage where I know basic chess strategies, but my rating is still below average. I can't find a source longer than a short article to learn from. Any suggestions? I can't really pay for things (my main roadblock) but I can if I have to. Thanks!!!

I'm an older player (84), but in my youth I read several chess manuals which explained all the basics and gave hints for improvement, such as books by I.A.Horowitz, Fred Reinfeld and Reuben Fine.  These are still available on eBay at reasonable prices.  And there are certainly more modern books that cover the same area, by Bruce Pandolfini, Jeremy Sillman, and Yasse Seirawan for example. But now in the era of the computer and the Internet, there is a readily available source of this information at your fingertips.  Just Google tips for chess improvement.  GM Arthur Bisguier for instance has written "Ten Tips for Winning Chess" which you can find there. And I'm sure there are countless others.  Then there's "YouTube" which has many free chess tutorials and also game analyses, such as by Agadmator and Mato.  I watch them there myself. Those are all good starting places. And of course you have to supplement what you learn by applying it in actual play.  Good luck on your chess journey!


Where can I find Pauls' 1874 article on the n-queens problem? Where can I find the following article, which concerns the n-queens problem?

  E. Pauls, Das Maximalproblem der Damen auf dem Schachbrete, II, Deutsche Schachzeitung. Organ f¨ur das Gesammte Schachleben 29 (9)(1874) 257–267.

The only old documents I find available online from the Deutsche Schachzeitung periodical are from Volumes 20, 21, 44, 45, 56, 57, which are available at the Internet Archive. So if you really are after Pauls' exact article for historical reasons, you might have to track down a hard copy of Volume 29 at a library.

On the other hand, if you are primarily interested in the mathematical content of Pauls' article, then a decent (though also partial) exposition is available from "A survey of known results and research areas for n-queens" by Jordan Bell and Brett Stevens, in Discrete Mathematics Volume 309, pp.1-31 (2009). For instance, they spell out Pauls' method of proof for the existence of solutions to the n-queens problem (which appears in the first part of the article for which you want the second part):

  Theorem (Pauls 1874). For all n>3, n non-attacking queens can be placed on the n x n standard chessboard.

The Bell--Stevens paper does point out that Pauls' part II gives a proof that the 92 solutions to the 8-queens problem given in 1850 by Nauck are exhaustive. But unfortunately,
Pauls' method of proof isn't given. (That said, Pauls' work here is mentioned alongside Gauss' earlier claim that a brute force computation could be used to prove that 92 is the total number, so perhaps that gives a hint at how Pauls proceeds.)

Edited to add: Bell and Stevens do point to two other old secondary sources which they say offer "excellent summaries" of prior work done on the 8-queens problem. These are:

E. Lucas, Récréations mathématiques. 2ième éd., nouveau tirage. Librairie Scientifique et Technique Albert Blanchard, Paris, 1973.
T.B. Sprague, On the eight queens problem, Proc. Edinburgh Math. Soc., 17 (1899), pp. 43–68.

The first is available online via Gallica (see the section on "Le problème des huit reines"), but it appears not to discuss the work of Pauls; rather, it focuses on the work of Günther (S. Günther, Zur mathematischen Theorie des Schachbretts, Arch. Math. Phys., 56 (3) (1874), pp. 281–292), which work also receives an English-language exposition in an 1874 Philosophical Magazine article by Glaisher.

The Sprague piece is also available online, via Google Books, but sadly it doesn't address Pauls either; instead, it again offers a look more at the Günther/Glaisher work, but this does at least mean explicitly addressing the matter of the 92 8-queens solutions on the standard chessboard, among other things.


How to be more aware of smothered mate opportunities? I've been playing ChessAcademy's android app for a while when I'm bored: thought it could improve my chess to be solving their tactic challenges (not sure if it's working though..).

One pattern I often fail to notice is the smothered mate. Today, I failed again to notice it while focusing on capturing pieces instead and leveling the score.

The challenge (and solution) is that one:

[FEN "3r3k/6pp/p3Qn2/P3N3/4q3/2P4P/5PP1/6K1 w - - 0 1"]

1. Nf7+ Kg8
2. Nh6+ Kh8
3. Qg8+ Rxg8
4. Nf7#

I failed by thinking of a move that would only turn the piece advantage to my side:

[FEN "3r3k/6pp/p3Qn2/P3N3/4q3/2P4P/5PP1/6K1 w - - 0 1"]

1. Nf7+ Kg8
2. Nxd8 Qxe6
3. Nxe6

Obviously the solution strategy is better, but I failed to see it (as I had in other challenges that included a smothered mate). So I was wondering what "signs" could I be looking for that a smothered mate is possible? I know it might sound a little obvious, but maybe if I start by just trying to notice some small patterns I'll fail less on those tactics and later be able to find more complex moves that set up a smothered mate.

There's a variety of mates that could be called smothered mate, but for what I'd call the "standard" one (sometimes called Philidor's Legacy), like the one in your example, notable signs are (with white mating black as an example):

The black king is in the h8 corner (maybe it just moved there after being checked by the white queen).
The white queen and knight control f7.
The f7 pawn is typically absent but g7 and h7 are still there (g7 and h7 could also be pieces, as long as they don't cover f7 or g8).
The white queen is on the a2-g8 diagonal.
There's a black rook on the 8th rank to do the smothering. (It wouldn't work with the black queen!)

This can be generalized to long castling, but it is less frequent.

Some tactical trainers (or books!) let you practice tactics by theme. I don't know anything about Chessacademy, but one example I know is the tactics in chess.com which has this feature and has a "smothered mate" category (but they use the term loosely!). Maybe after seeing many smothered mates in a row your recognition of them will become more automatic.


How does the last move in the Michael Adams vs Anatoly Karpov game result in the end of the match? In the Michael Adams vs Anatoly Karpov (1994, Dortmund GER, rd 1, Jul-15 ) match (moves listed [here][1]), the last move is indeed a check to the black king, but why did the match end after that ? I don't see the last move as a check-mate.

[1]: http://www.chessgames.com/perl/chessgame?gid=1014464[Event "Dortmund"]

[Site "Dortmund GER"]
[Date "1994.07.15"]
[Round "1"]
[White "Michael Adams"]
[Black "Anatoly Karpov"]
[Result "1-0"]
[ECO "B17"]
[PlyCount "117"]
[FEN ""]
[StartPly "117"]

1.e4 c6 2.d4 d5 3.Nd2 dxe4 4.Nxe4 Nd7 5.Nf3 Ngf6 6.Ng3 e6 7.Bd3 c5 8.O-O
Be7 9.Qe2 O-O 10.Rd1 Qc7 11.c4 Re8 12.dxc5 Nxc5 13.Bc2 Ncd7 14.Ng5 Nf8 15.
N3e4 Bd7 16.Nxf6+ Bxf6 17.Qd3 Bxg5 18.Bxg5 Rac8 19.Rac1 Qe5 20.Qd2 Bc6 21.
b4 b6 22.Bf4 Qf6 23.Bg5 Qe5 24.Re1 Qb8 25.a4 Ng6 26.f3 Bb7 27.Bb1 h6 28.
Be3 e5 29.Qf2 e4 30.f4 Qd6 31.Qd2 Qf6 32.b5 Nh4 33.a5 bxa5 34.c5 a6 35.c6
Ba8 36.Bd4 Qd8 37.Rxe4 axb5 38.c7 Qd7 39.Rxe8+ Rxe8 40.Qd3 Ng6 41.Bf2 Bc6
42.Qxd7 Bxd7 43.Rd1 Nf8 44.f5 Rc8 45.Bg3 b4 46.Bd6 Nh7 47.Be4 Nf6 48.Bb7
Re8 49.Be5 Bxf5 50.Rd8 Kh7 51.Rxe8 Nxe8 52.Be4 Nxc7 53.Bxf5+ g6 54.Bxc7
gxf5 55.Bxa5 b3 56.Bc3 Kg6 57.Kf2 Kg5 58.Kf3 h5 59.h4+ 1-0

Black has the dismal choice of being checkmated or watching his pawns drop off. If he takes the h pawn Bf6 is mate, if he drops the king back white will soon win the f pawn by wasting moves with his bishop if necessary, and then the others will follow. A few example lines below, Black's cause is really quite hopeless

[Event "Dortmund"]
[Site "Dortmund GER"]
[Date "1994.07.15"]
[Round "1"]
[White "Michael Adams"]
[Black "Anatoly Karpov"]
[Result "1-0"]
[ECO "B17"]
[PlyCount "117"]
[StartPly "117"]
[FEN ""]

1.e4 c6 2.d4 d5 3.Nd2 dxe4 4.Nxe4 Nd7 5.Nf3 Ngf6 6.Ng3 e6 7.Bd3 c5 8.O-O
Be7 9.Qe2 O-O 10.Rd1 Qc7 11.c4 Re8 12.dxc5 Nxc5 13.Bc2 Ncd7 14.Ng5 Nf8 15.
N3e4 Bd7 16.Nxf6+ Bxf6 17.Qd3 Bxg5 18.Bxg5 Rac8 19.Rac1 Qe5 20.Qd2 Bc6 21.
b4 b6 22.Bf4 Qf6 23.Bg5 Qe5 24.Re1 Qb8 25.a4 Ng6 26.f3 Bb7 27.Bb1 h6 28.
Be3 e5 29.Qf2 e4 30.f4 Qd6 31.Qd2 Qf6 32.b5 Nh4 33.a5 bxa5 34.c5 a6 35.c6
Ba8 36.Bd4 Qd8 37.Rxe4 axb5 38.c7 Qd7 39.Rxe8+ Rxe8 40.Qd3 Ng6 41.Bf2 Bc6
42.Qxd7 Bxd7 43.Rd1 Nf8 44.f5 Rc8 45.Bg3 b4 46.Bd6 Nh7 47.Be4 Nf6 48.Bb7
Re8 49.Be5 Bxf5 50.Rd8 Kh7 51.Rxe8 Nxe8 52.Be4 Nxc7 53.Bxf5+ g6 54.Bxc7
gxf5 55.Bxa5 b3 56.Bc3 Kg6 57.Kf2 Kg5 58.Kf3 h5 59.h4+ Kh6
    ( 59...Kxh4 60.Bf6# )
60.Kf4 Kg6 61.Bb2 f6
    ( 61...Kh6 62.Kxf5 Kh7 63.Kg5 )
    ( 61...Kh7 62.Kxf5 Kh6 63.Bc3 Kh7 64.Kg5 )
62.Bc3 Kh6 63.Kxf5 Kg7 64.Bxf6+ 1-0


Should a player be forced to move a piece that he has picked up after a spectator knocked it off the board? While anyone can answer this, I do have official FIDE arbiters in mind.

I am following a discussion on chess.com about the worst way you have lost a game. Someone related this story:

  This didn't happen to me, but it's the worst way to lose a chess game
  that I ever witnessed:

  I was playing in a tournament in Saint John, NB. It was raining
  outside, and there were a few spectators circulating around the
  playing hall... very likely, they just came in to get out of the rain.

  A player (let's call him "White pieces") at the table next to mine had
  just played his King from g1 to h1, to get out of an awkward pin on
  the c5-g1 diagonal. His opponent made his reply, and it was White's
  move again.

  A spectator wearing a heavy raincoat turned away from the game, and
  the corner of his coat clipped the White King (sitting on h1) and
  knocked it off the table. White pieces reached down to pick the King
  up and set it back on the board.

  His opponent said "Touch move".

  The tournament director upheld his claim. White pieces was forced to
  move his King, and the only available square was right back to g1...
  back into the pin on the diagonal.

  White lost the game a few moves later; as much because the "touch
  move" incident had left him completely demoralized as because of the
  two wasted moves K(from g1)-h1 and then back to g1.

I replied that I could not believe any reasonable TD/Arbiter would enforce that, but someone replied that that is what the rule says. I believe that intent to move it matters, so I am still skeptical. What would the rules say that apply and how would you rule?

As a note, another similar post regarded someone accidentally knocking over his king, and the opponent saying that it amounted to resignation.

I also would not mind a USCF interpretation if anyone has one.

Thank you.

I am not an arbiter, but here's what the rules say:

Rule 4.3 (emphasis added)

  if the player having the move touches on the chessboard, with the intention of moving or capturing

I think it should be clear to any reasonable person that picking up a piece that was knocked down by a spectator does not imply intent to move.

Perhaps the arbiter went with an overly narrow interpretation of "accident", though, from 4.2.2:

  Any other physical contact with a piece, except for clearly accidental contact, shall be considered to be intent.

I would still argue that picking up a piece that was knocked down is an accident according to the spirit of the rules. Obviously the piece must be "adjusted" since it's not just a matter of centering it a little bit on its square, but of picking it up from the floor. Therefore the intent to "adjust" is implied.

The USCF rules are similar in that they refer to intent to move, but additionally, there is a rule that might have helped in this case: 10H says "there is no penalty for touching a piece that is off the board". The main idea given the rest of the paragraph concerns promotion, but I think it would also apply here. (And I just noticed that the FIDE wording on the rule also says "on the chessboard". I don't know how I missed that the first time!)


Is this line of vienna attack a draw? Most chess players will recognize this position from the so called immortal draw:

[FEN ""]
1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2 4. Kxf2 Qh4 5. Ke3 Qf4 6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4 10. Kxa4 Nc5 11. Kb4 a5 12. Kxc5 Ne7 13. Bb5 Kd8 14. Bc6 b6 15. Kb5 Nxc6 16. Kxc6 Bb7 17. Kb5 Ba6

I am trying to understand if after Bxf7+ it is a force draw (with best play), I checked this opening site and after Bxf2 there is almost 88% of draw in this position.

With best play, the position is unclear. If White plays 7. Kc3, then after 7...d4+!, Black gets a slight advantage. However, White can play 7. Qe1! and then the position is unclear.

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

    1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 6. Kd3 d5
    7. Kc3 (7. Qe1 $1 Nf6 8. c3 Bd7 9. Kc2 (9. Nc5 Bb5+ 10. Kc2 Qxf1)
    9... Bxa4+ 10. b3 Qxe4+ 11. Qxe4 Nxe4 12. bxa4 Nf2 13. Ba3 Nxh1 14. Nh3 f6
    15. Bd3 Ng3 16. hxg3 Nc6)
    7... d4+ $1 8. Kb3 Qf6 9. Nf3 (9. a3 Qc6 10. Ka2 Qxa4) 9... Bd7 10. a3 Na6
    11. Ka2 Bxa4 12. Bc4 Bd7 13. Rf1 Qe7 14. d3 f6


How to download Stockfish and install it on the Fritz/ChessBase GUI? I'm on Windows 8. I have the Fritz/ChessBase GUI since I bought both Fritz 12 and Houdini 3 Pro.

I would like to know how exactly can I download and install the free latest version (and most powerful version) of Stockfish.

I've found this website to download Stockfish: http://stockfishchess.org/

But after I click on the big green button that says "Download Stockfish 5 for Windows" I don't know what to do. Should I select "Save File" or "Open with"? And after that what do I do?

Please try to explain it step by steps because I'm not that good with computers.

.

.

@AlwaysLearningNewStuff: Thanks for your answer, but I did not succeed. I downloaded the file. I moved it to C:\Program Files (x86)\ChessBase. I clicked on "Create UCI engine".

Then I clicked on the "..." button (which looks to be the "Browse..." button). I went in C:\Program Files (x86)\ChessBase.

But then clicking on one of the three files does not work.

Maybe the problem comes from the fact that the icon for Stockfish is different than the the other icons:

First download StockFish. You click on the button shown in the below image and choose "Save as". It will be saved as .rar file, which you can open with WinRar, 7Zip or similar utility...

Then you unzip it ( put it where you want ). After that run Fritz, and choose Engine -> Create UCI engine like in the picture below:

The following dialog box will pop up, after which you need to press Browse button:

Then you will see a dialog box that will help you find StockFish. Once you find it, select it and click Open ( in the picture below I didn't click on the StockFish when creating screen capture; sorry, I just forgot to do it ) :

After Fritz finishes loading engine your dialog box should look something like the image below. Then just click on the OK button:

That should do it. I think that the procedure is the same for ChessBase. To use StockFish instead of Fritz, press F3, select StockFish from the list of engines in the dialog box that pops, and click OK button. Wait a few seconds and you will be good to go.

That's all, if you need further help leave a comment. Best regards.