Key-Squares in Pawn Endgames In an instructional video, I have found this position:

The instructor (Dr Muller) says about key squares that are marked with green. I am unable to get the idea behind how Dr Muller determined these squares as Key Squares. I have practiced it many times in Fritz but fail to understand the exact technique that I should employ. The instruction goes rather fast and not helpful for beginners.

Please help me to proceed as white from here.

If the white king reaches one of the green key squares, then white will win. There is no rule determining those squares, just concrete analysis. However, once we have the key squares in place, we can systematically search for pairs of corresponding squares.

If the white king is on d8, then the black king must move to f8.
If the white king is on d7, then the black king must move to f7.
If the white king is on d6, then the black king must move to f6.
If the white king is on c8, then the black king must move to e8.
If the white king is on c7, then the black king must move to e7.
If the white king is on c6, then the black king must move to e6.

If at any stage black to move has the king already placed on the square corresponding to the square of the white king, black is in zugzwang and will lose.

This example turns out to be a quite simple case of (distant) opposition and 1. Kb7! wins for white.


Bad Stockfish evaluation This is the study

[fen "3B4/1r2p3/r2p1p2/bkp1P1p1/1p1P1PPp/p1P4P/PPBK4/8 w - - 0 1 "]

As you can see, Stockfish gives an absolute decisive win for black, though it is clearly a draw!!

Check it out yourself

c4+ is a losing move, while Ba4+ is the correct one.

What's going on? Doesn't Stockfish take into consideration closed positions at all?

Stockfish isn't a perfect chess-playing entity, and you've found a position where it's unable to tell is a draw (at least until the 50 move rule kicks in and helps it prune). These positions are called "fortresses". You can tell this is happening because even if you input the solution, Stockfish still evaluates the final position as -10 or more. These fortress positions where Stockfish is dead wrong are few and far between, but they exist, and this is one of them.

There've been various attempts at writing fortress detection code in Stockfish and other conventional engines which are meant to recognize fortresses and stop Stockfish from heading for them if its position is superior. If you have a smart idea, you can probably publish it in an academic journal (see the publications in the chessprogramming wiki).


Is chess a sport? If yes, then why? Sometimes (e.g. at some schools) chess is considered to be a sport. Is chess a sport? I view sport as a physical activity.

For instance, if a doctor asks you "Are you doing any sports?" would your answer "Yes, I play chess twice a week!"? It sounds a bit strange in my ears.

Is chess a sport?`

If yes, then why and to what extent?

Thanks!

The question of whether chess is a sport depends entirely on the context of the question. In certain situations, it may be useful to classify chess as a sport. For example, as you mention, in some schools chess is considered a sport because it matches the requirements of a sport in that context - an activity that pupils can engage in outside of academic learning that essentially keeps them out of trouble. Yet in other contexts, as when sport means to exercise some muscle group or improve fitness or some physical ability, chess would not typically be considered a sport.

On a deeper, philosophical level, the question is meaningless. "Sport" has no objective, unambiguous definition, it is a cultural concept that changes in meaning depending on time, culture, fashion and many other factors.


How to make a time-efficient thinking system? It is said that given enough time even an average player can play the "best" move in any given position.

Thus the real question in chess is that of time control. It has been argued by several chess tutors/authors (e.g Dan Heisman) that differences in a player's "thinking system" is what differentiates a patzer from a master. Because both players have the same amount of time in which to make moves, the one with superior time management (which, in this sense, is used to mean "how long it takes to make a good move/the best move") will win.

If we give the patzer unlimited time, but the master normal time controls, in theory the patzer should win (or at the very least draw).

So, how does one create an algorithm (aka a thinking system) that allows the player to make good moves (but not necessarily the "best" moves, since that would be impossible) while still being time-conscious? How do the masters do it?

Things to consider:

How would such a system operate?

Would it be hierarchical or web-like?

Would it consider each position a separate case with its own algorithm or be totally universal?

How much should memory (of openings and games) be involved?

There is some truth in what you say, time management obviously plays a role. I often feel that I can compete with IMs if I have twice the time. (Incidentally in my last game against an IM this theory was put to the test, he spent half of his time smoking and I managed to win the game).

But, if the difference in playing strength between you and your opponent is too big, no amount of thinking time will help you overcome it. Chess is first and foremost a game of understanding and intuition. If you haven't acquired this understanding before the game, no amount of thinking will lead you to conclusions that might just be obvious for a GM.

In that sense playing a game of chess is similar to writing a poem. Say, you and Shakespeare have a sonnet competition going on. He will have ten minutes, you will get ten hours. No amount of thinking will give you his vocabulary and feel for the english language.

There are super GMs who have an atrocious time management (Grischuk comes to mind). So it isn't a factor that totally cripples your chess strength. But, to finally come up with some actual advice:

Be confident.
Avoid perfectionism.

Everything else is experience and common sense. There is no mechanical "algorithm" that is applicable for a human being.
Recommended reading: The seven deadly chess sins, by Jonathan Rowson.


Seeking in-depth coverage of this French defense sideline [FEN ""]
    1. e4 e6 2. d4 d5 3. Nc3 Nc6

I am seeking high-level, in-depth coverage of the above line.

I was able to find small coverage in ECO C and liked what I saw there.

Is there any book/article that thoroughly deals with this line?

I would give more info, but I am not a French player. Still, I find the line very fun, hence the question.

There's a 12-page chapter on this position in Cristoph Wisneski's "Play 1...Nc6!: A complete chess opening repertoire for Black."  In that book it's reached via 1.e4 Nc6, 2.d4 d5, 3.Nc3 e6.  More generally you're probably more likely to see this discussed in books on the Nimzowitsch defense (with d5, not e5) rather than French defense books.


When should I trade into opposite colored bishops? This is something that always confuses me. If I have an edge, I may trade and the game becomes drawish. If I am down, I seem to trade and I get ground down.

I'm aware of things like potential weaknesses or space to consider, and I know that putting pawns on the same colored square as your bishop should be avoided.

But how do you evaluate if the advantage is enough? And what does give advantage e.g. what pieces left on the board are better for the attacker? What sort of checklists are there? I know that for R&P endgames, there is an active rook and so forth, but with opposite colored bishops it seems less clear.

This is a separate question from actual technique. I just know I avoid trades to opposite colored bishops on principle, because I'm clueless about them, and that's a big problem. And while it's fun to see GMs capitalize, I still don't have an idea of the thought that goes into when to trade.

Opposite-colored bishop endgames aren't always drawn; it depends on the pawns. The drawish aspect comes from the fact that either bishop can halt a passed pawn in its tracks, and the opposite bishop can't help overcome the barricade.

If you have a positional or material advantage, avoid going into such an OCB ending if you can. If you can't, then start action on both sides of the board, creating a passed pawn on each. Sac a pawn to accomplish this, if necessary. This will force your opponent to dedicate his bishop to one side and his king to the other.

Leave your bishop to guard one wing, preferably the wing where the opponent's pawns are less of a threat, and/or yours are easier for the bishop to defend. Then, send your king over to help push the passed pawn (or create one). He can chase the opponent's bishop away, or force it to give itself up for the passed pawn your king, but your bishop can't. So, king on offense, bishop on defense.

Also, try to keep your king in front of the pawns, so he can cover their advance squares.

Note: The OCB ending is an exception to the endgame rule of having your pawns on squares of the opposite color to your bishop. The exception applies only to the defender. If you follow that rule, your opponent's bishop will pick them off, and your bishop won't be able to defend them. So, if you're defending an OCB ending, put your pawns on the same color squares as your bishop.

If you're the attacker, put your pawns on squares of the opposite color to your bishop. That way, they cooperate with the bishop to keep the opponent's king away or drive him off.

If you're defending an OCB ending, keep your king on the same wing as, and in front of, the opponent's pawn majority, and defend your (possibly weak) pawns on the other wing with your bishop. Blockade your opponent's passed pawn with your king. Put your king on a square of your bishop's color, so your opponent's bishop can't dislodge it.

If you can, try to leave the base pawns of your pawn chains where your bishop can reach all of them quickly. If you can arrange two chains, one on each wing, with the bases near the center, then your bishop may be able to defend both from just one square.  If your opponent's king comes over to try to drive your bishop off Defense Junction, then he can't reach the pawns. No way to make progress.

If you can't arrange this, then try to stagger the chains a bit so that your bishop and king can navigate across the board, and keep an eye on the pawns at the bases of the chains. Leaving a few gap squares is important for the king's mobility, because if you don't stagger the chains and your king has to use the opposite colored squares to cross the board, your opponent's bishop can usually just attack the squares around the pawns when your king tries to get through, and block it.

Move a pawn only when absolutely necessary.  If he can't make progress, you'll get your draw.

Almost every endgame book treats this topic; I recommend a couple, such as Howell's Essential Chess Endings, Glenn Flear's Starting Out: Minor Piece Endgames, or Bruce Pandolfini's Endgame Course. Andrew Soltis' GM Secrets: Endings has an especially understandable and thorough discussion of "Bees of Opps".

So, the short answer is: Trade into an Opposite-Colored Bishops ending if you're likely to lose otherwise, and use its special characteristics to save the draw. This can sometimes work even if the opponent has 3 connected passed pawns, and you have none!


Trading off two rooks for queen and pawn I have hardly if ever seen 2 rooks being traded off for queen and pawn (or for just queen) in common games.

  Under what conditions is this trade-off advisable?
  Why is it fairly uncommon?

If anything, it would be advisable to trade one's queen for the opponent's rooks, not vice versa.  But it all depends on the position.  If my opponent's queen is particularly useful to him and dangerous to me, and my rooks haven't been well developed, especially if I'm already ahead in material, I wouldn't hesitate to exchange my rooks for the queen.

Also, in the middle game, if my opponent's rooks are passive, and his king is exposed, I might prefer to exchange away my rooks in favor of having my queen to worry the king with.  In some positions, a queen and minor piece can be more effective than two rooks and a minor piece.  Such positions generally occur during the middle game, when the opponent's many pawns and minor pieces hamper most offensive rook moves.  In contrast, the queen can do very well with her great scope, especially when supported with one or two well-situated minor pieces.

Two rooks for queen and pawn - well, it would depend a lot on the pawn, and on the position.  I would almost certainly trade two rooks for a queen and passed pawn, but I'd regard the opportunity with suspicion if the pawn in question was an underdeveloped doubled pawn already amply guarded against by my pawns.  More than likely, I'd be able to pick up such a pawn later, if it turned out to be necessary.

However, I would consider it a definite material advantage at most times to exchange my queen for two rooks.

The likely reasons why you don't see it much are that 1) the opportunity isn't all that common, and 2) the side getting the two rooks generally becomes stronger, so his opponent will want to avoid it.


What is the best move in this situation? This is my first post on CSE, so I appreciate any guidance on how to frame my questions from now on.

Here is my question: I want to know what the best move is in this sitiation.

  [FEN ""]

1.e4 c5 2.d4 e6 3.d5 ?

I was playing Black, and I won this game, but by moving my pawn to d5. a very dangerous situation will be created that can be irritating until the end of the game.

I understand that we should not allow such scenarios, but my specific questions are:

How to defend in such scenarios theoretically?, and on the other hand,
What lines could White play to win this game (if such a thing is even possible)?

but by moving pawn to d5 a very dangerous situation will be created that can be irritating until the end of the game.

It can be dangerous to both sides. Positions of these type are generally characterized as the Benoni Defense. They are unbalanced and offer more chances for complicated play. So you may or may not want to avoid such positions depending upon how comfortable you are playing such positions.

  How to defend in such scenarios theoretically?

A good idea for Black is to immediately take on d5, followed by moving the pawn to d6, blockading the pawn on d5. A sample line of development for Black may go like this -

  [FEN ""]

  1. e4 c5 2. d4 e6 3. d5 exd5 4. exd5 d6 5. Nf3 Nf6 6. Nc3 Be7 7. Be2 O-O
  8. O-O Na6 9. Re1 Nc7 10. a4 b6 11. Bc4 a6

The strongest player to consistently play this opening successfully was Bent Larsen. I recommend you take a look at the following games of Larsen to see how Black not only defends this position but also manages to seize the initiative.

Alberic O'Kelly de Galway vs Bent Larsen 0-1 1967

Svetozar Gligoric vs Bent Larsen 1/2-1/2 1969

Wolfgang Unzicker vs Bent Larsen 0-1 1970

Miguel A Quinteros vs Bent Larsen 0-1 1974

Incidentally, even Garry Kasparov once tried this idea in his early days.

Yuri Balashov vs Garry Kasparov 1/2-1/2 1979

  What track could white take to win this game almost surely (if such a thing is even possible)?

It is not known yet whether White can forcibly win in this line. Strong players continue to use this line, although it is not popular at the highest level; but that might simply be because of reasons like taste rather than the objective quality of the position.


Similar opening positions and structures When I first started chess, my mentor asked me to learn one opening that I like and stick to it, study it and master it. But things will not always go the way you think, your opponent might not always start 1. e4. However, starting 1. e4, 1. d4 , 1. Nf3... might leads to the same position after a sequence of moves (considering the in between moves to reach that position does not consist of a blunder).

What is the most common opening position(s) / structure(s) to be in regardless of the starting move? This is because by studying those, I think I can try to shape the board into those positions which I'm comfortable in.

There are two paths you can choose and they both depend on the current pawn structure you play.

You see, I understand exactly what you face here, as I have the same problem. When you work or have other reasons not to devote yourself to studying chess, you need to learn the least amount of openings possible in order to focus on more important stuff such as tactics/endgames/middlegame.

Therefore you need openings that are immune to transpositional tricks, but on the same side you can reach their middlegame positions as Black anytime. At best, you will need two openings -> against 1.e4 and against everything else.

As I have said, there are two choices:

FIRST CHOICE :

CARO-SLAV PAWN STRUCTURE

You can use Caro-Kann defense against 1.e4 and Queen's Gambit against 1.d4. These two openings have a lot of similar middlegames and studying pawn structures for both sides will greatly help you. Compare the below diagrams to see what I mean:

[Title "Queen's Gambit"]
[fen "8/pp3ppp/2p1p3/3p4/2PP4/4P3/PP3PPP/8 w - - 0 1"]

And this one:

[Title "Caro-Kann"]
[fen "8/pp3ppp/2p1p3/3p4/3PP3/8/PPP2PPP/8 w - - 0 1"]

Now consider exchange variations that can crop up from those structures:

[Title "Queen's Gambit declined"]
[fen "8/pp3ppp/2p5/3p4/3P4/4P3/PP3PPP/8 w - - 0 1"]

And notice that this is the same position only with the colors reversed:

[Title "Caro-Kann"]
[fen "8/pp3ppp/4p3/3p4/3P4/8/PPP2PPP/8 w - - 0 1"]

This means that if you take time to learn Carlsbad pawn structure you could cut down the amount of work drastically.

Furthermore, both Caro-Kann and Queen's Gambit declined are immune to transpositional tricks so White is unable to "kick you out" of your opening choice:

[Title "Caro-Kann"]
[fen ""]

1.e4 c6 2.c4 d5!

This is a line from Caro-Kann and is considered unclear. On other moves Black simply transposes into well explored lines as well.

[Title "Queen's Gambit"]
[fen ""]

1.c4 c6 2.e4 d5!

And you are back into Caro-Kann. On other moves Black simply transposes into well known lines.

On 1.e4 you could also use French defense, but it will require more work on middlegame structures, as they differ from the ones in Queen's Gambit. Still, the total number of lines you need to learn is lesser than the ones in Caro-Kann :

[Title "French defense"]
[fen ""]

1.e4 e6 2.c4 d5!

This is a good line for Black, covered in any repertoire book for French defense. Also, if White tries to trick you to not play Queen's Gambit he will fail and you can transpose into French defense:

[Title "Queen's Gambit"]
[fen ""]

1.c4 e6! 2.e4 ( 2.d4 d5! ) 2...d5!

And in both cases you are "in your opening", thus refuting White's try for tricking you out.

SECOND CHOICE:

The second choice is Sicilian defense-Dragon variation or Modern defense for 1.e4 and King's Indian defense on 1.d4.

A lot of work is required here, but these openings give better winning chances for Black than Queen's Gambit and French / Caro-Kann defense. They are also immune to transpositional tricks.

The pawn structure is nearly identical for all of these openings:

[Title "KID, Sicilian Dragon and Modern"]
[fen "8/pp2pp1p/3p2p1/2p5/8/8/8/8 w - - 0 1"]

It all depends on what you want:

QGD + Caro-Kann/French give you positional play, yet KIA and Sicilian/modern tend to be much sharper.

I chose QGD and French, and never regretted it, because I always "stayed in the opening" and the ideas are clear and simple. Still, I must add that these are harder to play then KIA and Sicilian/Modern, and achieving victory with Black is nearly impossible against quality opposition.

In the end, I recommend you Andrew Soltis-Pawn Structure Chess to help you grasp the middlegame concepts. With proper repertoire books you should be OK.

Hopefully this helps you a bit, if you have further questions leave a comment and I will try to help you.

Best regards.


White's c5 in Semi-Slav (or Slav) Defense Lately, I've been experimenting as white with pushing the c pawn in the Semi-Slav Defence, but mostly in blitz games, so I would be very thankful if some of you could analyze a bit and point out if there are any major drawbacks compared to other moves, as longer games could look quite different.

[fen " w - - 0 1"]

1. d4 d5 2. c4 Nf6 3. Nc3 e6 4. Nf3 c6 5. Bg5 Nbd7 (5... Be7 6. e3 O-O 7. c5) 6. e3 Be7 (6... h6 7. Bf4 Be7 8. c5) 7. c5

My prerequisite for playing c5 is that I managed to get bishop out to g5/f4/g3 and pushed a King's Pawn to e3, while my opponent didn't push his bishop to b4 (so it's on f8/e7/d6).

In the next few moves I usually play Be2/Bd3 and O-O, and later on it depends on the opponent's response.

What usually happens afterwards is that my bishop is pushed to h2-b8 diagonal (if it wasn't already there), and if black goes for pawn-exchange on Queen's side (by e.g. (X)... b6 (Y). b4 bxc5 (Z). bxc5), I have a strong b-line due to my bishop preventing opponent's Rb8.

Some other players block out Queen side pawns and try to get my black-square Bishop for a Knight, but I feel like it still leaves me stronger.

Some examples of live games:

[fen "r1bqk2r/pp1nbppp/2p1pn2/3p2B1/2PP4/2N1PN2/PP3PPP/R2QKB1R w - - 0 1"]

7. c5 a5 8. a3 O-O 9. b4 b6 10. Be2 Ba6 11. O-O Bxe2 12. Qxe2 Re8 13. Bf4 Nh5 14. Be5 Nxe5 15. Nxe5 Nf6 16. Nxc6 Qc7 17. Nxe7+ Rxe7 18. Nb5 Qc6 19. Nd6 g6 20. Qf3 Kg7 21. Qg3 axb4 22. axb4 bxc5 23. b5 Ne4 24. Nxe4 Qc8 25. Qe5+ Kg8 26. Nf6+ 1-0

OK, my opponent made a clear mistake with 14... Nxe5, it seems like not playing this position very often is one of the reasons why it happens, as this was a Blitz game. But that's exactly why I'm asking, as you can't expect such mistakes that often in classic games.

Another example:

[fen " w - - 0 1"]

1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. Nf3 Bg4 5. Bf4 e6 6. e3 Bd6 7. Be5 O-O 8. Be2 a6 9. c5 Be7 10. O-O a5 11. a3 b6 12. b4 bxc5 13. bxc5 Nbd7 14. Bg3 Ne4 15. Nxe4 dxe4 16. Ne5 Bxe2 17. Qxe2 Nxe5 18. Bxe5 f6 19. Bg3 Qd5 20. Rab1 Rab8 21. Bxb8 1-0

Again, the opponent made a blunder with 20... Rab8, but I think I was already in a considerably better position at that point.

[fen " w - - 0 1"]

1. d4 d5 2. c4 c6 3. Nc3 e6 4. Nf3 h6 5. Bf4 Bd6 6. Be5 Bxe5 7. Nxe5 Nd7 8. Nxd7 Bxd7 9. c5 Nf6 10. e3 a6 11. Bd3 b6 12. b4 a5 13. a3 axb4 14. axb4 Rxa1 15. Qxa1 b5 16. O-O O-O 17. Qa7 Qa8 18. Ra1 Qxa7 19. Rxa7 Rd8 20. f3 Kf8 21. Kf2

I made a mistake later on and ended up with one pawn less, but managed to get a draw. However, at this point of the game, I'm in a clearly better position.

[fen " w - - 0 1"]

1. d4 c6 2. c4 d5 3. Nc3 e6 4. Nf3 Nf6 5. Bg5 Be7 6. e3 O-O 7. c5 Nbd7 8. b4 Nh5 9. Bxe7 Qxe7 10. Be2 Nhf6 11. O-O e5 12. dxe5 Nxe5 13. Qd4 Nxf3+ 14. Bxf3 Be6 15. a4 a6 16. Rad1 Nd7 17. Bg4 Bxg4 18. Qxg4 Nf6 19. Qf4 Rae8 20. h3 Ne4 21. Nxe4 Qxe4 22. Rd4 Qc2 23. Rfd1 Qxa4 24. Qc7 Qb5 25. Rg4 Qe2 26. Rdd4 Rb8 27. Qe5 Qe1+ 28. Kh2 g6 29. Rh4 Qxf2 30. Qg5 Rbe8 31. Qh6 Qxg2+ 32. Kxg2 f5 33. Qxh7# 1-0

In this game, there were significant mistakes on both sides, but once again, it's Blitz so it happens.

What I want to know is, if you were black, would you be happy with me as white playing c5, and why (or why not)? I have troubles finding games with c5, so I guess there must be a reason why it isn't popular. But I know the move itself isn't that problematic (there are better moves perhaps, but a lot of popular openings are often played with suboptimal moves), so why is it so rarely played?

This is problem 34 from The Reassess Your Chess Workbook: How to Master Chess Imbalances by IM Silman. The notes are derived from his annotations:

  White has tried many moves here: 9. e4, gaining central space, and 9. b3, preparing to fianchetto the c1-Bishop and also giving White the chance to meet ...dxc4 with bxc4, both make sense. How would you judge the aggressive 9. c5?

[FEN ""]
[StartPly "16"]

1. Nf3 d5 2. d4 Nf6 3. c4 c6 4. Nc3 e6 5. e3 Nbd7 6. Qc2 Bd6 7. Bd3 O-O 8. O-O Qe7 9. c5 Bc7 10. e4 dxe4 11. Nxe4

What does White achieve in the final position?

Better control over e4 and d6
Black's freeing maneuver of b6 and c5 has been stopped
Although d4 is a backward pawn, it cannot be attacked so easily and helps cramp Black

For why c5 is not as popular, Silman offers:

  At one time this move would have been the object of derision; White makes a one-move threat that's easily dealt with and... takes all the pressure off the Black d5-pawn.

In summary, c5 is played to gain space, hence cramping Black.


How much time it takes before searching for tactical themes becomes a subconscious process? I would really like to have that ability.So how to achieve that?

It is a bit like for example learning to play the piano.
At first as a beginner you look at the keys and where your fingers are going.
With increasing practice, and remember even a great piano virtuoso() will still practice every day, your thought patterns become better organised and you later play with your fingers seemingly doing the thinking for you.
() The great Artur Rubinstein practised several hours each day: he said that if he did not do this he would detect a decline in his performances.
For each player the speed that this happens will vary.
I find playing through lots of master games is most helpful.
I try to read any annotations and play through some of the variations given in the analysis.
At first I was slow and cumbersome but after a while this improved.
The secret is consistent practice.
Every day without fail set yourself the task of playing through 1 to 20 games. Little by little patterns of play will be absorbed and you will find yourself subconsciously playing better moves.
By the end of a month you will have played through 30 to 600 master games.
By the end of a year you will have played through 350 to 7000!
Create for yourself a concrete set of steps for each game.
I used to have them typed on a card and reviewed the steps before each tournament game.
After a while they become second nature.
Two phases: 1. It is your opponents move.
2. It is your move.
I can elaborate these steps if it is of interest.


(Opening) Traps whose only solution is to grab material There are some opening lines where grabbing material is very dangerous – another question of mine serves as a good example.

However, are there some trick lines where the only reasonable choice is to grab extra material leading to a game playable for the player offering material? At first some gambits come to mind where one has to take a pawn first, but rather often gives it back quite soon.

I hope there exist a lot of examples, and maybe this question will see a lot of great answers then. To specify the question, I am searching for opening ideas where:

In a position which is roughly equal, one side (player A) sacrifices a lot of material – more than a pawn, the more the better.
The other side (player B) has to take that material in order not to get a worse position.
After B grabs that material, A gets a playable position. (That does not mean sacrificing material had to be the best move available.)
Ideally these lines occur rather often in actual games. Such a trick on move 24 in an opening no one plays is of course less interesting.

When I answered your other question and mentioned that a semi-bluff sacrifice works better if the best counter is to take the material, I actually had a specific opening line in mind.

I have never played the line with black myself, but I recommended it to a friend, who won some very nice games against stronger opposition.

The line I'm talking about is a sacrificial variation of the Löwenthal-Sicilian. You sac a pawn on your ninth move and continue with a rook sacrifice. The line I give below is just a sample line. There's quite a little tactical labyrinth for white to navigate. There is no direct refutation, only a better endgame for white in some line that I cannot remember. There are a lot of ways for white to go wrong, even if he doesn't take the rook for example, it can be quite tricky to get the knight out again.

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 5. Nb5 a6 6. Nd6+ Bxd6
7. Qxd6 Qf6 8. Qd1 Qg6 9. Nc3 d5 10. Nxd5 Qxe4+ 11.Be3 Nd4 12.Nc7 Ke7
13. Nxa8 Nxc2 14. Kd2 Nxe3 15. fxe3 Nf6 16. Qb3 Rd8 17. Ke1 Ng4


How many moves can be expressed with algebraic chess notation? I am wanting to write a chess engine (see here: Creating chess engine, machine learning vs. traditional engine?). The first step I am doing is taking a position in as an FEN and converting this position into an ideal move. Pseudocode would look something like this:

Position → Move

or using notation:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 → e4

I am trying to create an enumeration of every possible chess move, and I feel that I may be missing some. This includes moves like "e4", "Nxf5", "Bg3+", "Qxh4#", "exf8N#". My total count of unique moves that can be expressed using algebraic notation is 1884. Can anybody confirm the total number of unique moves that can be expressed using algebraic notation? My full list of moves can be found here: https://pastebin.com/xDNqbFt2

I immediately notice that you've missed the castling moves (O-O and O-O-O).

I would list the pawn-promoting moves according to their PGN syntax (=Q/R/N/B suffix), as that's the most commonly used in computer chess.

Algebraic notation can be ambiguous for sliding and leaping pieces (everything except pawn and king, actually) which may require specifying the origin rank, file, or both.  The latter is only needed for queens, bishops and knights, as rooks are always disambiguated by one or the other.

It might be useful to treat the suffix codes indicating whether the move results in check or checkmate as orthogonal to the move itself, since pretty much any move can theoretically have those results.  This would effectively divide the number of unique moves you need to handle by three.  Conversely, the different promotions of a pawn definitely should be considered as unique moves.


Illegal move or checkmate? I was playing chess with an opponent. He had his queen in front of his king. I attacked the queen and he moved her, exposing his king directly to my rook. It was my turn to move, not his. We couldn't decide if this was a checkmate. We know that  moving one's king into check is illegal. What happens however, if one removes a piece in front of his/her King and exposes him to checkmate unintentionally, as in this instance? If it's illegal to do this, but the player makes this move anyway, is he required to take back the move and move differently, or does the game automatically end? Thanks in advance.

It was illegal to move the queen here (and any piece in general) if that move put the king in check from another of the opponents pieces.

If the player tried to move the queen here they have to put it back and make a legal move.

Note that in some nonstandard variation most usually of the blitz speed type the special rules allow you to take the king and win if they make that illegal move.

Some other variations may allow claiming a win if an illegal move is made.  I have played blindfold games where that illegal move was a loss by the special rules for that variation of chess.


A question on psychology / strategy in Chess opening Is it a good idea to play unusual openings (minus the d&e files), such as c4 played by Bobby Fischer in his “Game of the Century”, to confuse the opponent and stop them from playing their natural opening in the rated tournaments?

There are many ways of looking at this depending on one's strength. Super Grandmasters are able to shift between openings with ease and still play them well at a very high level and with deep understanding. As for middling players, it is good to stay with one opening line for long and there are several advantages to that;

Experience is a very important aspect in the road to mastery and there's no shortcut to acquiring experience. The great martial artist, Bruce Lee once said,

  I fear not the man who has practiced 10,000 kicks (chess openings) once, but I fear the man who has practiced one kick (chess opening) 10,000 times.

The same could also be said about chess and sticking with one (or a few) opening lines for long time, acquiring more experience, deepening your understanding in strategic & tactical ideas behind the opening and both the resulting middlegames and endgame positions.

Don't play against the player but play against the pieces. Most great masters of the past including Bobby Fischer himself have stayed with one opening repertoire for long and playing fearlessly against all their opponents. Fischer played just a few openings, Ruy Lopez, Sicilian Najdorf, King's Indian Attack & Defense, Grunfeld Defense, and others in between. Some openings and variations have been named after masters simply because they remained loyal for long and built indepth understanding in those lines.
The desire to win quickly and the creeping in of last minute doubt in one's opening repertoire is what has led many players to run away from their main weapons, hoping that the new unknown opening will yield better results in their favor. More often than not, it is the same players that end up surprising themselves with their own lack of experience in the new unusual opening than surprising their opponents. The sad is thing is that after the game, there isn't much to analyse or to add to your experience in that surprise opening.

For serious tournament games, I would strongly recommend sticking with one's main opening repertoire and using surprise openings for blitz and casual chess. As for beginners, I would recommend that they should stay with simple openings that adhere to basic opening principles (develop your pieces quickly, knights first, king safety, etc) like the Italian Game before trying to surprise anyone.


Can someone explain why should white lose his queen in the following tactics? This is my initial position:

I exchanged my pawn to get queen at this position:

Now to complete the tactics, the engine is accepting only this move which results in a stalemate

I would have dominated black with my queen and bishop but the tactics did not allow to do so which implies losing queen is better. But I don't understand why.

I am trying to understand why is Q5f the best move for white.

At this position you pretty much lost already - except if you can save yourself into a stalemate. That is exactly what is happening in your example. Qf5 forces black to make a decision between one of the following choices: He can either move his king or his pawn, or he can take your queen.

If he chooses to move the king out of check or block the check with his pawn, white is free to take the black queen. While it is not an easy victory, playing with a queen against two bishops and a pawn can still be won.

If however black chooses to take white's queen, then white will be trapped in a stalemate, resulting in a draw. Getting half a point is better for white than losing (and getting no points). Given the imbalance of the material, there is also no way that white can win this endgame (against a reasonable well playing black player).

Explanation for the stalemate: After the white queen is taken, white only has his king left. But the king can't move anymore. The square d4 and d2 are controlled by black's (black) bishop. d3 and e2 are controlled by the black bishop on b5 and e4, d3 (again), f4, f3, f2 are all under the control of black's queen.


What counts has "having enough material to mate"? I'm aware that if one's flag falls then the game is declared a win for the opposing side if something like "they have enough material to mate" or "it is possible to mate". I'm curious about an edge case which actually differentiates between the above two scenarios, i.e. the opposing side has enough material to mate but it's impossible to mate from that position (for whatever reason).
I think an example would illustrate best the situation I had in mind. Suppose White has a King on a1 and a Queen on a2, while Black only has a King on h1. If White then plays Qh2+ (perhaps in an online bullet game) and Black's flag falls, does White win? Note that from this position it is impossible for White to mate, since Black's only legal move here is to play Kxh2, which would be an immediate draw.
There are other scenarios which would be impossible to mate, e.g. if White has a King on a1, pawns on a4, c4, e4, g4, and Black has a King on h8, pawns on a5, c5, e5, g5 -- clearly neither side can mate from this position. (This sort of situation is slightly less interesting to me as this is position that is less likely to arise than the one described above, but I'm still curious.)

From FIDE Laws of Chess, article 5.2b:

The  game  is  drawn  when  a  position  has  arisen  in  which  neither  player  can  checkmate the opponent’s king with any series of legal moves. The game is said to end  in  a  ‘dead  position’.  This  immediately  ends  the  game,  provided  that  the  move  producing the position was legal. (See Article 9.6).

In your first example, as soon as White plays Qh2+, the statement "a  position  has  arisen  in  which  neither  player  can  checkmate the opponent’s king with any series of legal moves" becomes true. As the rule says, this immediately ends the game with a draw. This happened on White's move and it immediately ends the game, so there is no time for Black's flag to fall.
The same happens in your second example. As soon as a dead position arises, it is a draw.
The position does not need to be dead for a fallen flag to result in a draw. Article 6.9 says:

Except  where  one  of  the  Articles:  5.1.a,  5.1.b,  5.2.a,  5.2.b,  5.2.c  applies,  if  a  player  does  not  complete  the  prescribed  number  of  moves  in  the  allotted  time,  the  game  is  lost  by  the player. However, the game is drawn, if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves.

So if Black's flag falls and there is no legal sequence of moves that results in Black's king being checkmated, it is a draw. For example, if Black has an extra queen in your first example, and Black's flag falls after this move
[FEN "8/8/8/5q2/8/8/Q7/K6k w - - 0 1"]

1. Qh2+

then it is still a draw, because there is no legal sequence of moves can result in Black's king being checkmated.


FIDE rules regarding use of foreign languages in algebraic notation Article 8.1a states that:

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

Appendices C2 and C3 state:

  C.2  Each piece is indicated by an abbreviation. In the English
  language it is the first letter, a capital letter, of its name.
  Example: K=king, Q=queen, R=rook, B=bishop, N=knight. (N is used for a
  knight, in order to avoid ambiguity.)
  C.3 For the abbreviation of
  the name of the pieces, each player is free to use the name which is
  commonly used in his country. Examples: F = fou (French for bishop), L
  = loper (Dutch for bishop). In printed periodicals, the use of figurines recommended.

Hence foreign languages and, indeed, foreign alphabets are allowed in the part of the notation denoting the piece moved. I believe I've seen Greek letters for pieces in a top level scoresheet.

However, C5 states:

  The eight files (from left to right for White and from right to left
  for Black) are indicated by the small letters, a, b, c, d, e, f, g and
  h, respectively.

C7 goes on to state:

  As a consequence of the previous rules, each of the sixty-four squares
  is invariably indicated by a unique combination of a letter and a
  number.

and then goes on to give a picture of a chessboard with the squares annotated with a1 through h8.

No allowance is made here for use of foreign alphabets and indeed in the aforementioned scoresheet that I saw the letters a through h were used for the files.

Am I correct in believing that the effect of these rules is that while native Russian, Greek, Arabic, Hebrew, Thai, Hindi, etc. speakers may use the standard abbreviations for the pieces in their own alphabets they must use the Latin letters a through h for the files rather than, for instance, alpha, beta, gamma, delta etc. for a Greek person?

As a native Russian player I may assure you that we always used the suggested notation, e.g. Фd4 or Лd1 (Ф - ферзь - for Queen, Л - ладья - for Rook, etc); even the 6 years old beginners did so. Nobody ever was insane enough to suggest Russian alphabet for encoding files.


How to realize this +2 evaluation in the Ruy Lopez, Steinitz defense I played a game as White using the Ruy Lopez: Steinitz defense against a lower-rated player (1594 vs. 1500 on chess.com). While I won the game due to a blunder by my opponent in a drawn endgame, the engine gives an almost +2 evaluation in the opening (+1.7 by move 10). But my advantage slowly decreased until it was a dead drawn 0.0 by around move 15. This was a 10 minute game, in case that is relevant.
[Event "Live Chess"]
[Site "Chess.com"]
[FEN ""]
[Date "2021.05.21"]
[Round "?"]
[White "Me"]
[Black "NN"]
[Result "1-0"]
[ECO "C62"]
[WhiteElo "1594"]
[BlackElo "1500"]
[TimeControl "600"]
[EndTime "22:27:44 PDT"]
[Termination "White won by resignation"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 d6 4. d4 exd4 5. Nxd4 Bd7 6. O-O Be7 7. Re1 Nxd4 8.Bxd7+ Qxd7 9. Qxd4 Nf6 10. c4 c5 11. Qd3 O-O 12. Bg5 Rad8 13. Bxf6 Bxf6 14. Nc3 Bxc3 15. Qxc3 b5 16. Re3 Rfe8 17. Rg3 g6 18. f3 bxc4 19. Qxc4 d5 20. Qxc5 dxe4 21. fxe4 Rxe4 22. Re3 Qd4 23. Qxd4 Rdxd4 24. Rxe4 Rxe4 25. Kf1 a5 26. Rc1 Re5 27. Rc7 Kg7 28. Kf2 h5 29. Ra7 Kf6 30. Ra6 Kf5 31. Ra7 f6 32. Rh7 Re4 33. Ra7 a4 34. Ra5+ Ke6 35. b3 axb3 36. axb3 Rb4 37. Ra3 Kd5 38. Ra5+ Kc6 39. Ra6+ Rb6 40. Rxb6+ Kxb6 41. Ke3 Kb5 42. Kd4 Kb4 43. Kd5 Kxb3 44. Ke6 g5 45. Kxf6 g4 46. Kg5 h4 47. Kxh4 g3 48. Kxg3 Kc4 49. Kf4 Kd5 50. Kf5 Kd6 51. Kf6 Kd7 52. g4 Ke8 53. Kg7 1-0

My justification behind trading the dark-squared bishop was to have the d5 square for my knight. However, it pretty clearly backfired quickly as my opponent just made the same trade as soon as it was possible. Then we were back to a fairly symmetrical position. I'm assuming the evaluation came from the d5 square for my knight, but otherwise, I don't see how to make use of this advantage. By playing out some alternative moves with the engine, my opponent's dark-squared bishop makes it to d4 and they get their own great piece.
What was the correct plan here for White to keep this advantage?

First things first, I don't believe thinking in terms of computer evaluation is useful at all for humans. We don't look at a position and go "Well, I guess that's about a +0.54".
Instead, I'd focus on the key elements of the position. By move 15, Black has a weak pawn on d6 that will probably stay weak for the entire game, while the d5 square is a great outpost for the White pieces. This reasonning leads us to what went wrong. Instead of keeping control of the semi-open file and weak square, you went on an attack on g7. That's okay, but you should have consolidated your position first. Moves like Rad1 and b3 would have been useful.
By move 21 your position has transformed. You're a pawn up but your pieces are poorly coordinated and Black controls the newly open files. Most endgames you will get into will be drawn with correct play and if anyone has a chance to create an attack, it's definitely Black.


Why do some strong players play 5... Be4 in Caro Kann, Tal Variation? [FEN ""]
1. e4 c6 2. d4 d5 3. e5 Bf5 4. h4 { B12 Caro-Kann Defense: Advance Variation, Tal Variation } h6 5. g4 Be4 6. f3 Bh7  7. e6 Nf6

What is the point of the intermediate move 5...Be4 before retreating by ...Bh7? It was played by very strong players, including Ding Liren (against MVL) and Hikaru Nakamura (against Mikhail Antipov).
If the point is to provoke f3, it seems to me that White is not unhappy to play f3 and control e4, as Black might play 6... Nf6 next, which is indeed a good move in these positons.
If the point is to disallow Nf3 in positions when White pushes e6 and Black takes with exf, it does not achieve that, as Black wasted one tempo on the bishop retreat Bf5-e4-h7 and White can also waste a tempo by playing f2-f3-f4 and then Nf3.
It does weaken g3, which Black could try to exploit with 7...Qd6, but after exf+ Kxf7 White can once again push f4 without feeling bad about wasting a tempo.

White probably intends to play e6 anyway, to launch an attack against the light squares. Whether Black takes this Pawn or allows exf7, White will want to play Nf3-e5 as part of his followup, and if f3 has been provoked, he will need to play f3-f4, losing another tempo and obstructing his dark Bishop.


Is Bobby Fischer hanging a knight? So I've been looking at the "Game of the Century" between Bobby Fischer and Donald Byrne. There's something I can't get over.

In move 18, that queen is tempting, but there's also a knight on c3 that is not immediately protected.

[Title "That knight on c3 appears to be hanging"]
[fen "r3r1k1/pp3pbp/1qp1b1p1/2B5/2BP4/Q1n2N2/P4PPP/3R1K1R w - - 0 1"]

Is there a reason, which I don't see, why White shouldn't just take the knight here? It seems to me that this takes the wind out of the sails of most of Black's attacks. It appears Black has no good way to recover, as Black still has to move his queen or lose it and the knight. And there's suddenly not a lot of good spaces to move it to either.

I would not normally answer this question since the other answer points out the basis for the first move of the variation, but only the first move. It left out why white is so lost in that variation, and why Byrne did not play it.

At the end of both lines below, there are written notes explaining the resulting position.

 [Event "New York Rosenwald-03"]
 [Site "New York"]
 [Date "1956.10.17"]
 [Round "8"]
 [White "Byrne, Donald"]
 [Black "Fischer, Robert James"]
 [Result "0-1"]
 [ECO "D97"]
 [PlyCount "82"]
 [EventDate "1956.10.07"]
 [EventType "tourn"]
 [EventRounds "11"]
 [EventCountry "USA"]
 [FEN ""]

 1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. d4 O-O 5. Bf4 d5 6. Qb3 dxc4 7. Qxc4 c6 8. e4 Nbd7 9. Rd1 Nb6 10. Qc5 Bg4 11. Bg5 Na4 12. Qa3 Nxc3 13. bxc3 Nxe4 14. Bxe7 Qb6 15. Bc4 Nxc3 16. Bc5 Rfe8+ 17. Kf1 Be6 18. Bxb6 (18. Qxc3 Qxc5 19. dxc5 (19. Rc1 Bxc4+ 20. Qxc4 Qf5 {And in this position, it is particularly hard to get the white king out because g3 is impossible due to Qxf3 (and if it moves or becomes defended, then Qh3 sealing in the Rh1), and again white is down a pawn with the worse minor piece, d4 is weak, and white is behind in development with a weak king. That the queens did not come off exacerbate that issue.}) 19... Bxc3 20. Bxe6 Rxe6 {And white is lost because he is down a pawn, the black bishop is much better than the white knight, both a2 and especially c5 are weak, and white is behind in development and has to deal with getting the Rh1 out. One more thing that would probably come into play also is that with the dark-squared bishop, f2 is particularly vulnerable too.}) 18... Bxc4+ 19. Kg1 Ne2+ 20. Kf1 Nxd4+ 21. Kg1 Ne2+ 22. Kf1 Nc3+ 23. Kg1 axb6 24. Qb4 Ra4 25. Qxb6 Nxd1 26. h3 Rxa2 27. Kh2 Nxf2 28. Re1 Rxe1 29. Qd8+ Bf8 30. Nxe1 Bd5 31. Nf3 Ne4 32. Qb8 b5 33. h4 h5 34. Ne5 Kg7 35. Kg1 Bc5+ 36. Kf1 Ng3+ 37. Ke1 Bb4+ 38. Kd1 Bb3+ 39. Kc1 Ne2+ 40. Kb1 Nc3+ 41. Kc1 Rc2# 0-1


What other games or chess variants are useful to improve your chess skills? I know about Chess960, and you can play that online at lichess.org. Furthermore, I like playing Go as well. But are there any good variants and other ways to train that you use, and you know to work well?

I believe that studying Shogi added 50 points to my chess game.  They are related games and thus share some related concepts.  I believe Shogi showed me things about chess I had not understood before.


Fastest way to parse a bitboard I am making a chess engine, and for now I’m working on the move generation. I’m using bitboards, and so for example my magic bit boards file for a knight on d4 is

00000000
00000000
00101000
01000100
000N0000
01000100
00101000
00000000
Which is represented by some unsigned long long integer.

I need this in a format where I can store the moves in a move list, and also make the move. E.g. {10,12,17,21,33,37,42,44}
What would be the fastest way to get the indices of the “1” bits in the bitboard during runtime? Currently I isolate the least significant 1 bit with x &= -x, and then XOR the position until I get 0. But is there a faster way to do this?

I found some well hidden pages in the Chess Programming Wiki.
The first one basically introduces your solution:
https://www.chessprogramming.org/Bitboard_Serialization#Single_Bits
However, the next chapter states that most applications are interested in the index of the square rather than its bitboard representation:
https://www.chessprogramming.org/Bitboard_Serialization#Square_Index_Serialization
This is done using a bitscan routine. There is another page dedicated to them:
https://www.chessprogramming.org/BitScan
It shouldn't be a surprise that the fastest method is to use processor specific instructions:
https://www.chessprogramming.org/BitScan#bsfbsr
If this is not possible, there are many other algorithms described there, which you can choose from.
There is also a Java dedicated version of this page, which describes API methods, which may be intrinsified by the VM:
https://www.chessprogramming.org/Java-Bitscan


Modus in the reykjavik open 2015 Is it correct that the reykjavik open 2015 is a KO tournament ?
If the game is a draw, does black achieve the next round ?

No, according to the tournament page; it is a Swiss.


Chess development strategy for U16 players with the aim of producing future masters on a national scale I have a vision of producing future chess stars in a country and I am looking for tips and advice on how to go about it. What would be the best approach or programme to adopt in achieving this dream by working with under 16 players (4 - 16 year olds). I would be interested in areas of study, approach strategies, and any other information that might be vital to chess development on a national scale.

I'm not sure there's one best way. The best way depends on the country: current chess level, number of chess players, the country's economy, etc.

That said, assuming we're talking your country specifically i.e. Botswana, or more generally a developing country where chess isn't very widespread, the first thing I'd look into is the funding provided by FIDE's Planning and Development Comission (PDC). As of 2019 they offer up to 20,000 USD that can be used for purchasing chess equipment, organizing tournaments, etc.

In fact, as you can see on PDC's website, Botswana's funding request for 2019 has been approved. So you should check with your national federation and see how they plan to use the money.

Now if we're talking about a hypothetical situation where you can decide how the money would be used (e.g. for 2020), I'd suggest:

allocate a small part (say 20%) of the funding to improve the situation for existing players (including adults): purchase chess sets, organize free or cheap tournaments, organizer an arbiter  seminar, organize classes for intermediate/advanced players, or even provide coaching to players likely to play in the Olympiad. Note I'm not suggesting you do all of these, as $4000 isn't that much, just what you need the most.
allocate the bulk of it (say 80%) to the long term vision: for example, train chess instructors -- think Developmental Instructors in FIDE parlance, that is, people who can teach the rules and the basic of chess to beginners, not FIDE Senior Trainers -- and then provide cheap or free classes to children on weekends or after school.

Ideally you would institute chess classes in schools across the country (like in Armenia), but of course that's very hard to pull off. Still, you can use the Armenian case as an example. You want to convince parents and school teachers that spending time on chess is beneficial for kids, that it's associated with good outcomes. Example article.

You want to focus on elementary school children. It may sound harsh, but if your goal is to produce masters, starting at high school is a bit late.


How would you evaluate this king and pawn endgame for white, and what's the best book to study King and pawn endgames? I would  like to learn more tricks and ideas behind these complicated endgames. For example, here is a game I played where I got into one (I was playing white).

[fen ""]
[Startply "83"]

1. e4  e6 2. d4  d5 3. Nd2  Nc6 4. Ngf3  Bb4 5. c3  Ba5 6. exd5  exd5 7. Bd3  Nf6 8. O-O  O-O 9. Nb3  Bb6 10. Bg5  Qd6 11. Re1  h6 12. Bh4  Bd7 13. Bc2  Bg4 14. Qd3  Bxf3 15. Qxf3  Rae8 16. Qf5  Ne4 17. f3  g6 18. Qh3  Nf6 19. Bg3  Qd7 20. Qxh6  Ne7 21. Qg5  Nh7 22. Qd2  c6 23. Bf4  Nf5 24. a4  Ng7 25. a5  Bc7 26. Bxc7  Qxc7 27. Nc5  Ne6 28. Nxe6  Rxe6 29. Rxe6  fxe6 30. Bxg6  Qg7 31. Bxh7+  Kxh7 32. Re1  Qg6 33. Re2  Rxf3 34. Qc2  Qxc2 35. Rxc2  Re3 36. Kf2  Re4 37. Re2  Rf4+ 38. Kg3  Rf6 39. b4  b6 40. axb6  axb6 41. Rf2  Rxf2 42. Kxf2  Kg6 43. Kf3  Kf5 44. h4  e5 45. g4+  Kf6 46. Ke3  e4 47. Kf4  Kg6 48. Ke3  Kf6 49. Kd2  Kg6 50. c4  Kf6 51. b5  cxb5 52. g5+  Ke6 53. c5  bxc5 54. dxc5  d4 55. g6  e3+ 56. Kd1  b4 57. c6  b3 58. c7  Kd7 59. c8=Q+  Kxc8 60. g7  Kc7 61. g8=Q  b2 62. Qc4+  Kb6 63. Kc2   1-0

Was this king and pawn truly won for white or did my opponent miss something? How could I have played better in the endgame?

There were a lot of inaccuracies by both players, I don't think you were ever losing, but you certainly threw away the win occasionally. I think three concepts might be helpful to you:

A protected passed pawn is very strong in a pawn endgame because it forces the enemy king to keep an eye on it at all times. Therefore allowing 46…e4 was a big mistake that turned an easy win into a draw. Instead take on e5, play h5 and h6 and then round up the black pawns.
Two connected passers are even stronger, because basically that's a dynamic duo of protected passers: The enemy king can never take the more backward one, because the other one will queen. And whenever possible, they will advance. See again move 46. If you take on e5 and black retakes with his king, you can fearlessly advance because as soon as the black king returns to g6 to attack the h6-pawn, you just protect it with g5.
The king is often curiously helpless against two pawns that aren't even connected and just one square apart: That's why 50.c4 was another big mistake. If black takes this pawn, there is no way for you to get at either the e- or the c-pawn. So 50…dxc4 51.Ke3 c3 and you cannot take on e4 because the c-pawn will queen. (Edit: Dag points out that after dxc4 b5 might still win for white, so maybe it wasn't a mistake, but the concept is still useful. Instead of dxc4, b5 should draw for black.)


Opening classification and transpositions Positions in an opening can often be reached in a variety of (meaningful) ways, i.e. by transpositions.

When classifying chess games (e.g. in databases or books) by , are there rules or other guidelines which of these transpositions to pick?

Your question has two different nuances, that is, how to classify an opening and how to classify a game.

The Encyclopedia of Chess Openings' only aim is to classify the first moves of a chess game, it does not concern itself with how the game develops nor further transpositions. Even if a widely known position is reached after an unorthodox choice of moves, the ECO will classify the opening according to these first moves. A comprehensive list can be found both in 365Chess and Wikipedia, the first provides easy access to the variation in question and the second provides the name and some contextualization for the variation.

While the ECO has not an analogous encyclopedia for complete games, the widespread and common way of treating them in the literature is to find the last instance of a known tabiya and consider the game under its umbrella. This ignores the concrete opening, which is often useful since the game may be a relevant addition to the theory on that position, and thus the particular move order leading to it is irrelevant.


Amount of search per decision: GMs versus AlphaZero and Stockfish In Demis Hassabis' presentation at the the Kinds of Intelligence Symposium in January 2018, grandmasters are compared to AlphaZero and Stockfish along an interesting metric: how many moves are searched per decision made? It is claimed that ``human grandmasters'' considers 10 of moves per decision they make, AlphaZero tens of thousands, and Stockfish tens of millions. Is there any scientific evidence regarding the number of moves per grandmaster or human in general? 10 seems to me a very arbitrary number. Where does it come from?

PS. I didn't know that grandmasters can be non-humans as well!

Edit. I missed this answer but my question is not about what make a grandmaster special? Or how many moves can foresee a grandmaster? I understand that any number would depend on the position. My question is I guess more precise: is there any scientific evidence, experiment, or study that tried to measure the average number of moves a human can consider during a certain amount of time?

My attempt was to read Alexander Kotov's book "Think like a grandmaster". Kotov asks this simple question: How many candidate moves a grandmaster examine? Kotov does not give any precise answer: ``they are unusual cases where there can be five or six, where in the next they are actually seven'' but his book dates back from the seventies (1971 for the English translation) and I was wondering if someone tried to test this more scientifically, by estimating an average number.

I assume you're wondering about the speed of calculating moves. I'm not sure how you would go about figuring out the max #moves a GM can calculate (I guess the experiment runs until they fall asleep?).

I'm an FM and I can calculate a couple of moves per second (1-3), assuming the calculation is trivial enough. For more complicated positions where I need to analyze in the middle of my calculations, the speed significantly slows down to how long I need to analyze. This depends entirely on the complexity of the position. GMs are probably slightly faster than me on average. I'm not sure where the "10 moves per decision" figure came from.

From what I understand of AlphaZero, it uses a very strong intuitive (generated from playing itself thousands of times) combined with Monte Carlo Tree Search. This search plays out random simulations of games, starting from where AlphaZero is calculating, and then the move that ends up scoring the highest is chosen.

Stockfish uses the typical minimax with alpha-beta search algorithm, combined with other algorithms which increase efficiency (esp. iterative deepening). It doesn't calculate to the end of the game in each branch, but instead goes up to a certain point and evaluates the resulting position based off its evaluation heuristics.

As for the speed of moves/second between AlphaZero and Stockfish, it comes down to how fast (on average) they can evaluate one position/node. The overall way they traverse the calculation tree is irrelevant when talking about raw calculation speed. Calculation speed comes down to two things:

The speed of the computer the Engine is running on.
The algorithm used to evaluate a position.

Assuming Stock and AlphaZero are given equal computers, then on average I would assume AlphaZero is faster (I don't have any official sources for this though). This is because it evaluates based off a very fined tuned intuition which it learned by playing itself over and over. Meanwhile, Stockfish uses evaluation heuristics thought up by humans. They're very good heuristics, but still only human made.

On ChessBase, Stockfish evaluates over 1 million nodes/positions per second. I don't know what AlphaZero's speed is, but when they eventually publish the engine you could check it out then.


What are the pairing regulations for a single-elimination (knockout) tournament? Here are the pairings for the 2017 FIDE World Cup. The above pairings are for 128-player knockouts. I can't get the way the pairings were generated. I want to be able to generate pairings using the same criteria for knockouts with different numbers of players.

Are there any FIDE published rules for single-elimination tournaments, such as the World Cup? If not, what are the criteria they use for such pairings?

As it stands, there are no knockout, single-elimination or pairing tags. I couldn't find appropriate tags, so feel free to re-tag this question.

The participants were seeded by their FIDE rating: the highest rated player (Magnus Carlsen, 2822) got #1; Wesley So, rated 2810, got #2, all the way down to Oluwafemi Balogun (2255), seed #128.

In the first round, the player with number x plays against the opponent with number 129 - x. So 1 vs. 128, 2 vs. 127, and so on.

In the second round, assuming the stronger player (with the lower number) advances, the player with number x plays against the opponent with number 65 - x. So 1 vs. 64 (this actually happened) and 9 vs. 56 (but this became 9 vs. 73 since 73 beat 56).

The 'target sum' for the third round is 33, for the fourth round 17, and so on until the final where #1 is supposed to play against #2.

This all is a standard seeding mechanism used in many sports (sometimes with slight variations); actually, in most cases, only the top n% (25% is common) of the players is seeded and the rest are paired randomly. This tournament was 'completely' seeded, which is relatively rare.


What was the role of the second in top level matches? What was the role, the duties, etc. of the second (e.g. GM Ray Keene was Korchnoi’s second in the 1978 World Championship match vs. Karpov), and is this figure still present in contemporary top level chess?

What was the role, the duties, etc. of the second (e.g. GM Ray Keene
was Korchnoi’s second in the 1978 World Championship match vs. Karpov)

What it most definitely was NOT was writing a book of the match ready to rush into print the moment the match finished as Keene did.
The way it was supposed to work was that after the time control was reached at move 40 one of the players would seal a move. The players would then go back to their respective hotels with their seconds and perhaps discus a few lines. The principal would then have a meal and go to bed. The seconds would then stay up all night analyzing the position and coming up with a list of variations for the principal to look at and learn when he got up the next morning.
On nights when there was a new game starting the next morning it was the job of the seconds to prepare opening lines based on the opponent's repertoire for the principal to look at the next morning.
Sometimes, in the build up before a world championship match, a player would hire a strong player for a secret match to try out ideas in a realistic match atmosphere. Botvinnik famously did this as did Anand.

is this figure still present in contemporary top level chess?

Very much so.
Today the main job of the second to do the dogsbody work of opening preparation for the principal. Part of this may be preparing the player to play against a particular opponent's repertoire. Jan Gustaffson has famously helped Carlsen with opening prep as this is his main area of expertise as a chess player.
The other more interesting part is to come up with new ideas in opening lines. This requires creativity and computer skills with engines because they play a big role. This doesn't automatically require GM level chess ability. Nakamura has famously employed the same sub-2200 player, Kris Littlejohn, since 2008 simply because Littlejohn comes up with many creative opening ideas, is very good at investigating them with engines and gets along well with Nakamura on a personal level.
There is more on the Nakamura-Littlejohn relationship in this Chessbase India Facebook video and this episode of Ben Johnson's Perpetual Chess Podcast.
There is more interesting information about seconds in this post.


How can a Stonewall Attack player respond to 1. ... f5? In Chess Psycholoyg: The Will to Win, William Stewart recommends playing the Stonewall Attack as white. This recommendation is one of a set of openings that are very similar and are therefore suitable for player's who don't want to memorise a lot of opening theory. (The other openings are the French Defence against 1. e4, and the Schallopp Variation of the Slav Defence against 1. d4.)

For the Stonewall Attack, Stewart describes the classical structure (1. d4 d5 2. e3 Nf6 3. Bd3 c6 4. f4 Nbd7 5. Nbd2 e6 6. Ngf3 Bd6 7. 0-0 0-0 8. Ne5 ...), how to play against 2. ... c5 (e.g. 1. d4 d5 2. e3 c5 3. c3 Nc6 4. dxc5 e5 5. b4 a5 5. Bb5), how to play against an early 2. ... Bf5 or 3. ... Bf5 (e.g. 1. d4 d5 2. e3 Bf5 3. c4 ...), and he recommends adapting to the King's Indian Defence with a Zukertort set-up (e.g. 1. d4 Nf6 2. e3 g6 3. Nf2 Bg7 4. b3 d6 5. Bb2 0-0 6. Be2 Nbd7 ...).

What is missing, since the book is not intended as an opening handbook, is what to play after 1. d4 f5. Is it best to continue the normal Stonewall set-up or is it better to deviate, like in the case of the King's Indian Defence? (The best response may even be a totally different anti-Dutch approach, but that's a different question.)

The game 1/2‒1/2(40) Dietze, Sebastian (2129) – Lorenz, Mark (2250) / Regionalliga NW 0506 (7.1), Bayern 2006, gave me a hint on how to proceed:

[FEN ""]

1. d4 f5
2. f4 Nf6 3. e3 b6 4. Nf3 Bb7 5. c3 e6
6. Bd3 Be7 7. O-O O-O  8. Nbd2 d5 9. b3 Ne4

After ... f5 I believe its necessary to stop that pawn with 2 f4; ... Nf6 was the best continuation according with an opening report, and following the same kind of white moves e3 / c3 / Bd3 to form a wall of pawns and positon the bishop to attack on diagonal b1–h7.

Dietze played 6 Bc4 which I saw as a move different of what you have shown us, therefore I preferred Bd3 and worked out the continuation with the help of a chess engine.

I see a balanced position, similar as the positions you have shown us and with a potential advance in the queen side.


Program to solve positions Are there any programs out there that take a completely won position and compute the minimum checkmate depth (say if it is around 50 moves)?

You need to use mate search function of a chess engine.

Some engines have this function, for example, Houdini 4: http://www.cruxis.com/chess/manual/index.html?game_play.htm

You can activate it using UCI parameters, or more easily, using a Fritz GUI on Windows as it has a mate search button, which makes life easier.


How is time measured when a player is late? When watching The Queen's Gambit I noticed that some players were late to their game. How is time measured in this case?
It is simple when the player playing black is late, because the one playing white would have done their move and switched the clock.
If the player playing white is late - is their clock switched on at the moment the game starts and is let to run?

Play starts when the arbiter announces the start of play, usually by saying "Start white's clock". A good arbiter will then walk round the tournament room making sure that all clocks have been started. If both players have yet to arrive at a table then the arbiter will start white's clock. If a black player has not started white's clock then the arbiter will do so and make a mental note to check back and make sure the black player doesn't stop them again as this could lead to the round finishing late.
If a player with the white pieces arrives late, therefore, then when they arrive they will have lost the time from the start of the round when the clocks were started. If the black player was on time then this will be when the black player started the clock. Otherwise it will be when the arbiter started the clock.
If a player with the black pieces arrives late then when they arrive they will have lost the amount of time since clocks were started minus the amount of time white used for the first move.
If the default time is, say, 30 minutes, then the arbiter will go round the room looking for empty seats with a clock with 30 minutes gone. This works for absent white players and for most black players. The exception is when David Howell is white and has taken 10 minutes for his first move.


Reply for C11 French/Steinitz after `5. Nf3 c5` When playing C11 French/Steinitz, 6. dxc5 Bxc5 is chosen. Even in Shredder, it's most played in C11 French/Steinitz. What should White best reply after 6. dxc5 Bxc5??

[FEN ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. e5 Nfd7 5. Nf3 c5 6. dxc5 Bxc5

Best Regard,
Ahmad

The plan for white is to secure the e5 square. Black's freeing maneuver will be to play f6, and the resulting position will have a backwards pawn on e6. Therefore, white's plan will be to place his bishop on f4 and move his knight to e5, perhaps with support along the e-file from a rook or queen.

A possible variation could continue as follows:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. e5 Nfd7 5. Nf3 c5 6. dxc5 Bxc5 7. Bd3 Nc6 8. Bf4 f6 9. exf6 Nxf6 10. O-O O-O 11. Ne5 Bd7 12. Qe2

Keep in mind that this isn't the only way of playing the Steinitz. White more commonly plays 5. f4, bolstering his center pawn on e5 before continuing to develop with Nf3. Also, 6...Nc6 is considered a more accurate move for black, leaving the option of capturing on c5 for a later move and saving a tempo to attack the e5 square.


Trying to locate a historical game in which the win involves sacrificing two rooks I can't remember whether White won or Black won, but I've been wondering for years where I saw this game. I remember toward the end, only heavy pieces and pawns were left, and the winner sacrificed two rooks so that only his queen faced his opponent's queen and rooks. I think resignation occurred before the checkmate, but the checkmate that was imminent was delivered by the queen supported by pawns.

Does anyone know this game or at least one like it? For a while I thought it was a Capablanca game, but I perused my book of his games and couldn't find it.

Could it be this game?

[FEN ""]
[Event "Living Chess Exhibition"]
[Site "Los Angeles, CA USA"]
[Date "1933"]
[Result "1-0"]
[White "Jose Raul Capablanca"]
[Black "Herman Steiner"]

1. e4 {From "Viaje al Reino del Ajedrez " de Y. Averbach et
al} e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Bb4 5. O-O O-O 6. d3 d6
7. Bg5 Bxc3 8. bxc3 Ne7 9. Nh4 c6 10. Bc4 Be6 11. Bxf6 gxf6
12. Bxe6 fxe6 13. Qg4+ Kf7 14. f4 Rg8 15. Qh5 Kg7 16. fxe5
dxe5 17. Rxf6 Kxf6 18. Rf1+ Nf5 19. Nxf5 exf5 20. Rxf5+ Ke7
21. Qf7+ Kd6 22. Rf6+ Kc5 23. Qb7 Qb6 24. Rxc6+ Qxc6 25. Qb4#
1-0

According to the comments on chessgames.com, this might have been a prearranged game.


Does permanent loss of castling rights reset three fold repetition? Threefold repetition requires that the same "potential for moves". For example, if an en passant move could be played in one position but not another, it does not count as the same position.

With respect to threefold repetition, would the positions be considered the same if:

In the first position, the king cannot castle because it is in check, pieces are blocking, or for some other reason, but it could castle otherwise.
In the second position, the king cannot castle because it has already moved.

According to the FIDE Laws of Chess:

  9.2.2 Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Thus positions are not the same if:

  9.2.2.1   at the start of the sequence a pawn could have been captured en passant
  9.2.2.2   a king had castling rights with a rook that has not been moved, but forfeited these after moving. The castling rights are lost
  only after the king or rook is moved.

Hence the answer to

  With respect to threefold repetition, would the positions be
  considered the same if:

  In the first position, the king cannot castle because it is in check,
  pieces are blocking, or for some other reason, but it could castle
  otherwise

Although castling is temporarily prevented the king still has castling rights. They are not lost if castling is temporarily prevented by check or blocking pieces. They are only lost if the king or rook moves.

With regard to:

  With respect to threefold repetition, would the positions be
  considered the same if:

  In the second position, the king cannot castle because it has already
  moved.

The rules are clear. If the king has lost castling rights since the the first position then the positions are not the same and a draw cannot be claimed.

  Does permanent loss of castling rights reset three fold repetition?

Yes. That's what the rule says.


Most recent "best in world" player who would be defeated by a CM Of the chess players who could reasonably be considered the best in the world in at least one year in history, how far back would you have to go before one of them would lose to a 2020 Candidate Master (or FM or IM) in a classical game? How would historical figures such as Steinitz or McDonnell or Ruy López fare against the different ranks of titled players?
(Going back far enough, mileage on rules like castling or stalemate may vary. If you think it makes a difference which player's version of rules is used then give the answer both ways.)

McDonnell was never best in the world, and I doubt he would have been stronger than 2200 FIDE, a candidate master would be an even match. Out of the best players in the world, both Philidor and Labourdonnais would both be capable of being defeated by a CM, with regularity. It is difficult to compare strengths of the players from the past, because they would be possibly strong GM level in tactical calculation, but weak in openings and modern strategy. But I would estimate a regular 2200 FIDE CM could beat them on occasion


Are the board positions of the 4 players of each country determined by Elo rating in chess olympiads? Are the board positions of the 4 players of each country determined by Elo rating in chess olympiads? Or is this something arbitrarily decided by the countries?

By board positions I mean, 1st seed/board, 2nd seed/board, 3rd seed/board and 4th seed/board.
I do remember seeing some players with higher Elo ratings sitting on lower boards, hence I am wondering what the regulations are.

Look for fixed board order in the FIDE handbook's Regulations for the Chess Olympiad. The essence is that the board order cannot be changed between rounds for the purpose of getting a strategic advantage.


Getting rid of a chess addiction How do I get rid of achess addiction? Both winning and losing just make me play more, and in the end, after many hours of play, I feel miserable.

You are probably referring to online chess and I know this problem, because I've suffered from online chess adiction at least a year or so.
It helped me to realise that those imaginary rating points online are not worth anything and that playing at fast time controls does not improve your chess (too much bullet might even harm it).

Therefore, I suggest, you approach chess a bit more seriously over the board, so you have successes you can be proud of. This means that you don't need the kick of online chess anymore, or at least that was the case for me.

Try finding something that makes you happy when you do it. For me, it is, at least sometimes, to be productive in any kind of way (choose an area of your liking) or to simply relax or hang out with friends. Generally speaking, playing lots of online chess is one of the LEAST PRODUCTIVE things you can do and nothing that will propel your skill in any area. Hanging out with your friends for instance, is a much better way of spending your time.
I mean, I could go on about this, but those are my initial thoughts. If you have any specific questions about how I got rid of my online chess addiction, you may as well shoot me a message.


What chess book or teaching approach is this from my childhood? When I was little (mid-late 90's) my mom taught me to play chess.  She had a book, which looked pretty old at the time (perhaps from the 70s but I could be off by a decade or more).  The book outlined the approach she used to teach me.
As the first step, she taught me only about the pawns.  We played entire games with ONLY the pawns.  Each player had eight pawns set up on their second row (the same positions as in normal chess), and the pawns moved exactly as in chess, including capturing en passant when legal.  The object of this game was to either get a pawn to the other side of the board, or to capture all the opponent's pieces.  This was a great game and a great introduction and was very easy to learn and remember.
My trouble is, I don't recall what the next step was.  It may have been to introduce rooks and play the same game but with rooks added.  That rings a bell, but I'm not sure.
I'm now teaching my 7-year-old son to play chess, and I'd love to be able to use the same approach I learned with as I know it was successful although I don't remember the rest of the details of the gradual approach.  (My mother passed away a couple years ago so isn't available to ask about it.)
Does anyone recognize this approach?  Does it have a name?  Is there a book (either a well known book or an obscure one) that uses this method as the first step toward teaching chess to a beginner?  (The book may have been giving an approach specifically for teaching children, or just a general method of teaching chess, I'm not sure.)

You can make it up yourself as you go along. You already know that chess is better learned with as few pieces on the board as possible, which puts you way ahead of the people who want to teach newcomers with all 32 units.
At the first meeting of a 10- or 12-week class, I teach the kids a game with eight white pawns and the black queen. If a pawn reaches the 8th rank (unlike chess, it doesn't have to survive the 'promotion'), the pawns win. If the queen gobbles all the pawns or blocks the last pawn remaining, the queen wins.
Some kids never get past that, but they get to enjoy the play time instead of struggling with chess, and the great thing about it is that it's an equalizer. I lose some of those games, and unlike chess, when I talk about why I'm making this move or that, the kids understand.


What is the bishop pair worth? It depends on the position but with all things being equal how much material value would you say the bishop pair is valued at?

There is a well known article called The Evaluation of Material Imbalances
by GM Larry Kaufman, first published in 1999 in Chess Life, winner of the 'Best Instruction' award from the Chess Journalists of America, that has the bishop pair valued at half a pawn.

A quote from the article (linked above):

  "The bishop pair has an average value of half a pawn (more when the opponent has no minor pieces to exchange for one of the bishops), enough to regard it as part of the material evaluation of the position, and enough to overwhelm most positional considerations. Moreover, this substantial bishop pair value holds up in all situations tested, regardless of what else is on the board. This large a bishop pair value is surprising because in the opening grandmasters will often give up the bishop pair to double the opponent's pawns or to gain a mild lead in development, factors which are generally not worth half a pawn..."

That same article values the other pieces like so:
King = 4 (endgame)
Queen = 9.75
Rook = 5
Bishop = 3.25
Knight = 3.25
Pawn = 1

Whether you wish to rely on such figures is up to you. Personally I think you would be better off exploring why the bishop pair is considered an advantage, and when. The best explanation I've seen is in Ludek Pachman's Complete Chess Strategy Vol 1.. Some of the points he raises:

  "In open positions their effectiveness is an extremely important factor."
  "...the opportunity of purposeful simplification."
  "The side with the two bishops can bring his king to the centre more easily under their protection"
  "...helps by preventing the enemy king from using the otherwise weak squares of a certain colour."


how to make long-range plans? I am intermediate Chess player, I can make common plans, but when it comes to create long plans, I can't plan. Can I please get some help? Thanks

Taking into account your earlier version of this question (with number of moves to think ahead, etc), I think you might be a bit confused about the terms. Basically chess is played using two methods:

tactics/calculation
positional play/strategy

Tactics/calculation

... is when you actually calculate concrete variations, i.e. something like: if I make this move, my opponent does this, to which I reply with this move, etc. When playing chess, in most positions you don't need to calculate very deep: perhaps 3 moves or less, or not at all. This is because most positions are rather quiet and you have a number of equally good moves available. Trying to calculate deep here would quickly exhaust your memory (e.g. if at each move you have say 3 possible moves to consider, then you already have 27 variations if you calculate 3 (half)-moves deep). Of course there are also positions where you need to calculate deep (say 10 moves), but if it is some forced line with few alternative candidate moves, it is not all that hard to do so.

Anyway, there are situation, where pure calculation does not help and you need another method to come up with moves, which brings us to...

Positional play/strategy

.. this is based more on intuition, experience, general principles and is much harder to train than tactics/calculation. To start with, you should familiarize yourself with common positional motifs. Don't need to learn all of them at once, but start with some easy important ones like "piece activity", "open file/file control", "king safety", "isolated pawns", "good pieces/bad pieces".

When playing a game of chess, try to take into account these factors, e.g. think what pieces are badly placed, check whether you can occupy an open file, etc. This will lead naturally to meaningful plans. If you run out of plans, learn a new positional motif and see whether this helps.

In the opening/middle-game, the plan is often determined by the pawn structure and you can read about it in: the wikipedia article

The tricky part comes, when you have several positional motifs available and need to decide for one or the other. For instance, is it a good idea to go for a pawn storm, if this neglects my king's safety?

In order to train such positional ideas, ideally, you have a stronger player look over your games and point out strategical mistakes (or compliment you on your strategical play). Another option is to read or watch annotated games and see what plans they develop in different types of positions. Learning this plan making will take time and many games in order to gain experience on what works and what does not. But don't worry, for most beginner games, tactics/calculation is much more important than long term strategy.


Why do chess engines sometimes miss good moves (or take forever to spot)? It is not the first time that I found a greatly superior move than the chess engine did, it even takes them a while to understand these moves after you make them.

For example, the move 15 ... Bf2 in the game below:

[fen ""]
[StartFlipped "1"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Ng4 5. h3 h5 6. hxg4 hxg4 7. Bxc6
gxf3 8. Qxf3 Qh4 9. Qh3 Qxh3 10. gxh3 dxc6 11. Re1 Bxh3 12. f3 Bc5+ 13. Kh2
Bf1+ 14. Kg3 Rh3+ 15. Kg4 Bf2 16. Rxf1 Rg3+ 17. Kf5 Rxf3+ 18. Kg4 Rg3+ 19.
Kf5 f6 20. d3 Kf7 0-1

The move remains unnoticed by the engine for a while, it is not until I move that it starts to see the rest of the iceberg.

I know it all depends on how much time you give them to analyze though, but it is unacceptable that sometimes humans manage to find these moves in less time than computers.

Why do chess engines fail to spot good moves in some positions? (I once read something about a 'horizon effect', maybe this is related?)
Are there other notable examples? (e.g this famous puzzle, it takes a while for computers to solve)

These questions contain useful information to partially explain some factors that might be causing this anomaly: What algorithms and heuristics are popular in computer chess?, When playing a Computer opponent what situations should I create to give myself a better chance of winning?, Computer evaluations: How trustworthy are they?

Notes: The trap is known as the Fishing Pole, I am aware I missed a mate in 3 (and a mate in 7) :(, the time limit per move was days (correspondence chess) but it took me like 5-10 minutes to finish calculating everything.

Why do chess engines fail to spot good moves in some positions?

The reason are called forward pruning techniques (see http://chessprogramming.wikispaces.com/Pruning)
with ProbCut in first line.

The move 15...Bf2 is pruned on shallow deeps because it includes the sacrifice 16.Rxf1 without regaining something concrete with evidence immediately after.
The matenet is also hard to see, because it includes some further 'silent' move
as for example 17...Ke7, and yes also engines, not only humans have difficulties to see distant silent moves as they are often pruned.

In this concrete case you even cannot say, that engines fail to spot good moves,
because also the continuation 15...Rh3h1 is a very good move and leads to an absolutely won position.

Last but not least you have to remember, that an engine's strength is always measured in terms of elo-strengh and not in the ability to find the absolute shortest way to win.
It does not matter, if a engine wins in 8 moves or in 25 moves.
Seeking to much for the shortest win, would mean a waste time, because most time there does not exist such a secret good move at all. And waste of time would hurt the engines ELO-Rating.


What is the technique to win and endgame R vs B + B? [title "R vs B+B"]
[fen "8/4rpkp/6p1/8/8/4BBP1/5PKP/8 w - - 0 1"]

The engine says that this endgame is winning for white(+2.5). Is there a technique that could be used to win this for white. I understand that the ideal position for black to draw this game would be to have 0 pawns on the board which would then with the best play be a draw. If there was a passed pawn in this for white the escorting of the pawn to the final rank would be achieved with the bishop maneuvers. However, in this case, the pawns are on the same side of the board. Are the engines missing some sort of fortress position or is there a winning technique?

As a complement to previous answers, notice that although this endgame should be a theoretical win for the bishops, it is not as straightforward a technical task as one might think.

Even at the highest level, in a World Championship Match, Black has been able to save his skin. The stakes were very high, since this rapid game was played during the tiebreak when the players were still tied.

 [FEN ""]
 [Event "Carlsen - Karjakin World Championship Match"]
 [Site "New York, NY USA"]
 [Date "2016.11.30"]
 [EventDate "2016.11.11"]
 [Round "13.2"]
 [Result "1/2-1/2"]
 [White "Magnus Carlsen"]
 [Black "Sergey Karjakin"]
 [ECO "C50"]
 [WhiteElo "?"]
 [BlackElo "?"]
 [PlyCount "167"]

 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.O-O Nf6 5.d3 O-O 6.a4 a6 7.c3 d6
 8.Re1 Ba7 9.h3 Ne7 10.d4 Ng6 11.Nbd2 c6 12.Bf1 a5 13.dxe5 dxe5
 14.Qc2 Be6 15.Nc4 Qc7 16.b4 axb4 17.cxb4 b5 18.Ne3 bxa4
 19.Rxa4 Bxe3 20.Bxe3 Rxa4 21.Qxa4 Nxe4 22.Rc1 Bd5 23.b5 cxb5
 24.Qxe4 Qxc1 25.Qxd5 Qc7 26.Qxb5 Rb8 27.Qd5 Rd8 28.Qb3 Rb8
 29.Qa2 h6 30.Qd5 Qe7 31.Qe4 Qf6 32.g3 Rc8 33.Bd3 Qc6 34.Qf5
 Re8 35.Be4 Qe6 36.Qh5 Ne7 37.Qxe5 Qxe5 38.Nxe5 Ng6 39.Bxg6
 Rxe5 40.Bd3 f6 41.Kg2 Kh8 42.Kf3 Rd5 43.Bg6 Ra5 44.Ke4 Rb5
 45.h4 Re5+ 46.Kd4 Ra5 47.Kc4 Re5 48.Bd4 Ra5 49.Bc5 Kg8 50.Kd5
 Rb5 51.Kd6 Ra5 52.Be3 Re5 53.Bf4 Ra5 54.Bd3 Ra7 55.Ke6 Rb7
 56.Kf5 Rd7 57.Bc2 Rb7 58.Kg6 Rb2 59.Bf5 Rxf2 60.Be6+ Kh8
 61.Bd6 Re2 62.Bg4 Re8 63.Bf5 Kg8 64.Bc2 Re3 65.Bb1 Kh8 66.Kf7
 Rb3 67.Be4 Re3 68.Bf5 Rc3 69.g4 Rc6 70.Bf8 Rc7+ 71.Kg6 Kg8
 72.Bb4 Rb7 73.Bd6 Kh8 74.Bf8 Kg8 75.Ba3 Kh8 76.Be6 Rb6 77.Kf7
 Rb7+ 78.Be7 h5 79.gxh5 f5 80.Bxf5 Rxe7+ 81.Kxe7 Kg8 82.Bd3 Kh8
 83.Kf8 g5 84.hxg6 1/2-1/2

White pieces were played by a grandmaster who is considered as one of the very best endgame players in History.


Chess engine with API I am looking for a chess engine which provides a normal API which I can use with some high level programming language like C# or python. I went through the list of leaders (Houdini, Komodo, Stockfish and Rybka) and was not able to find any signs that these engines provides API (which surprised me and suggested that I am missing something).

To be less vague, here is what I need from this API:

be able to load specific game into the engine
be able to evaluate position of the game
be able to make a move

So, does anyone knows an engine which provides a clear API to it's functions?

As others have said, UCI is the API you want.  The full specifications of the protocol is here (the zip file extracts to a text file): http://download.shredderchess.com/div/uci.zip

It's actually very straight forward and simple, a UCI engine must respond to and reply in plain text through stdin, stdout and stderr.  In fact, you should be able to launch the executable binary of any UCI engine on your platform and issue the UCI commands manually.

UCI facilitates instructions from a GUI or other engine to tell the specific engine to do whatever it is that you want it to do, including analyse a specific PGN file (the loading of it is through the GUI or similar front-end, the raw moves are then fed to the engine in extended algebraic form, such as e4 becoming e2e4).  The second and third points of your requirements are standard with UCI, but it is up to each engine developer to support them (given how lean those requirements are, that should be most of them).

Here's an example of UCI in action on the command line:

bash-3.2$ ./stockfish-5-64
Stockfish 5 64 by Tord Romstad, Marco Costalba and Joona Kiiski
uci
id name Stockfish 5 64
id author Tord Romstad, Marco Costalba and Joona Kiiski

option name Write Debug Log type check default false
option name Write Search Log type check default false
option name Search Log Filename type string default SearchLog.txt
option name Book File type string default book.bin
option name Best Book Move type check default false
option name Contempt Factor type spin default 0 min -50 max 50
option name Mobility (Midgame) type spin default 100 min 0 max 200
option name Mobility (Endgame) type spin default 100 min 0 max 200
option name Pawn Structure (Midgame) type spin default 100 min 0 max 200
option name Pawn Structure (Endgame) type spin default 100 min 0 max 200
option name Passed Pawns (Midgame) type spin default 100 min 0 max 200
option name Passed Pawns (Endgame) type spin default 100 min 0 max 200
option name Space type spin default 100 min 0 max 200
option name Aggressiveness type spin default 100 min 0 max 200
option name Cowardice type spin default 100 min 0 max 200
option name Min Split Depth type spin default 0 min 0 max 12
option name Threads type spin default 1 min 1 max 128
option name Hash type spin default 32 min 1 max 16384
option name Clear Hash type button
option name Ponder type check default true
option name OwnBook type check default false
option name MultiPV type spin default 1 min 1 max 500
option name Skill Level type spin default 20 min 0 max 20
option name Emergency Move Horizon type spin default 40 min 0 max 50
option name Emergency Base Time type spin default 60 min 0 max 30000
option name Emergency Move Time type spin default 30 min 0 max 5000
option name Minimum Thinking Time type spin default 20 min 0 max 5000
option name Slow Mover type spin default 80 min 10 max 1000
option name UCI_Chess960 type check default false
uciok
isready
readyok
quit
bash-3.2$

The commands I issued were uci, isready and quit.

To utilise the UCI commands you essentially have two main choices; you can use an existing interface (e.g. ChessX, Arena and a host of others) or you can write your own code to issue instructions to an engine or group of engines.  I believe there may already be Python wrappers for accessing UCI engines, but I'd need to double-check.  There's definitely python-chess (import chess) and pychess (import pychess), I just can't recall the extent of their functions.  I can't recall where pychess is lurking (probably github or google code), but python-chess can be installed with pip.


Has the King's Indian Defense been refuted at the Grandmaster level? I know about b4 in the bayonet and the Kramnik-Kasparov games of course.  I also know that Mr. Radjabov has been unhealthy (hope he gets better soon) lately.  Thanks in advance, your site is awesome, your work on the albin counter is a gift from heaven.

Short answer - no.

Plenty of strong grandmasters like Radjabov and Caruana still play it.

Latest games


Games that illustrate attacking themes I have recently made an agreement with a bunch of highly interested but still inexperienced players and I will become their trainer. My plan is to have 1-2 meetings per week with them to talk about some relevant strategical topics and prepare their "training plan" for the days we will not meet (by now, consisting mostly of tactics and analysis of their own games)

I could find some illustrative games for most of the strategical themes that I would like to have a look at with them, like open files, the 7th rank, minor piece comparison (good and bad bishop, active and passive knights...), as well as pawn structure. I've also chosen a list of must-know theoretical endgames for them to learn.

However, before starting with these "more subtle" strategical topics, I would to begin with a few lessons on material and attack. Material advantage and simplification are no problem, but I am struggling to find illustrative games showing different types of attack. Ideally, the games should be easy to understand from a tactical perspective (by that I mean that, despite of course there being tactical complications, the strategical ideas should still be clear behind the forced-move mess) Classical games are also preferred since modern ones often require a great understanding of a particular type of position to follow, and I would prefer to show a more global view of attacking in chess.

Could you please provide me some reference to attacking games you consider illustrative/enjoyable? Any help is appreciated, even it you only contribute with one game.  I would like to cover the following topics:

Attacking a king in the center. First game in Nimzowitsch's book is great here. Morphy also comes to the rescue. What other examples do you know?
Converting development advantage into attack against the king.
Piece power in opened-center positions.
Maneuvering the pieces into the enemy's castled position (more closed-position focused)
Bayonet attacks (opposite-side castling): Here I am pretty much served, as some opening books on the Sicilian and French made the job for me, but other examples are welcome.
Bayonet-attacks (kings castled on the same side): The best examples I found come from the King's Indian Defence. What else can I look for?

(After finding a good collection of games, I intend to show them 1-2 games per theme, and give them the rest so that they can make the analysis themselves) Thank you for your time!

When it comes to maneuvering pieces to an enemy's king in a position, the following famous game with a king walk comes to my mind. The position isn't quite closed, but it does illustrate an attacking theme of walking the king across the board to a castled king. It has been nicknamed "A Long Walk Off a Short Peer" by chessgames.com.
[Title "Nigel Short-Jan Timman, Interpolis 15th, Tiligribg Netherlands, 1991"]
[FEN ""]

1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. Nf3 g6 5. Bc4 Nb6 6. Bb3 Bg7 7. Qe2 Nc6 8. O-O O-O 9. h3 a5 10. a4 dxe5 11. dxe5 Nd4 12. Nxd4 Qxd4 13. Re1 e6 14. Nd2 Nd5 15. Nf3 Qc5 16. Qe4 Qb4 17. Bc4 Nb6 18. b3 Nxc4 19. bxc4 Re8 20. Rd1 Qc5 21. Qh4 b6 22. Be3 Qc6 23. Bh6 Bh8 24. Rd8 Bb7 25. Rad1 Bg7 26. R8d7 Rf8 27. Bxg7 Kxg7 28. R1d4 Rae8 29. Qf6+ Kg8 30. h4 h5 31. Kh2 Rc8 32. Kg3 Rce8 33. Kf4 Bc8 34. Kg5


How do delay and increment work, exactly? I am trying to program my own chess clock and would like it to be as accurate as possible. Suppose 2 players, player A and player B, are playing a 15 minute game with a 2 second delay. Suppose A is white, and the game begins, and player A spends 2.5 seconds on his first move before hitting the clock. The first 2 seconds are "absorbed" by the delay, but what happens when it is his turn again? He will get the 2 second delay, but will 15:00 change to 14:59 half a second after the delay has finished, essentially giving him a free half-second? Or does the fractional time get rounded up to the nearest second? Similarly with increment.

Nothing gets rounded internally. If you are programming a chess clock, then maintain the time according to whatever the machine precision is on your machine without rounding. Some clocks have tenth seconds on their display, but that doesn't mean that they're altering the fundamental increments of time as compared to different clocks.

If A begins and spends 2.5 seconds on his first move, then he will have exactly 14:59.5 left. Just because it displays 15:00 doesn't mean that he still has 15:00. If he spent 2.6 seconds, then he has exactly 14:59.4 left, which may display as 14:59.

Likewise with increment. He will have exactly 14:57.5 + 2 = 14:59.5 seconds on his clock, which may display as 15:00.