# Question
Title: Hardware used in AlphaZero vs Stockfish match
I understand that AlphaZero has to use a different kind of hardware than regular Stockfish. I would expect that the hardware has a large effect on engine strength. That's why I wonder whether there have been any attempts made to provide comparable hardware to both. Also what would "comparable" mean here?

Specifically I read that people complain about:

* Stockfish being given only 1 GB of cache, and
* the time limit of 1 min/move (How would this disadvantage Stockfish?)

# Answer
> That's why I wonder whether there have been any attempts made to provide comparable hardware to both.

This is Google you're talking about! So the answer is obviously "No".

From the original paper hardware used for initialising and training -

> Training proceeded for 700,000 steps (mini-batches of size 4,096) starting from randomly initialised parameters, using 5,000 first-generation TPUs (15) to generate self-play games and 64 second-generation TPUs to train the neural networks

and hardware used for the games -

> AlphaZero and the previous AlphaGo Zero used a single machine with 4 TPUs Stockfish and Elmo played at their strongest skill level using 64 threads and a hash size of 1GB.

So, AlphaZero used special hardware developed by Google. It used specialized Tensor Processor Units (TPUs) rather than general Central Processing Units (CPUs) as are available commercially.

This is how Wikipedia describes the second generation TPUs they used -

> The second generation TPU was announced in May 2017. Google stated the first generation TPU design was memory bandwidth limited, and using 16 GB of High Bandwidth Memory in the second generation design increased bandwidth to 600 GB/s and performance to 45 TFLOPS. The TPUs are then arranged into 4-chip 180 TFLOPS modules

They used 4 TPUs for the games, so a processing power of 180 TFLOPS. Note TFLOPS = 1000 billion floating point operations per second.

For comparison Intel's latest most powerful chip is the Core i9 Extreme Edition processor which clocks in at 1 TFLOP. A top of the line I7 that you would find in a gaming machine would typically be about 100 GFLOPs (i.e. one tenth of a TFLOP).

I think it's fair to say that AlphaZero was using an 800 pound gorilla of a hardware configuration compared to Stockfishes mouse.
> 25 votes

# Answer
I think it's best if I elaborate on your second point with an example move in the game 1 between AlphaZero and Stockfish which also served to satisfy my curiosity today.

> the time limit of 1 min/move (How would this disadvantage Stockfish?)

Stockfish's performance is dependent upon both the time limit *and* the hardware configuration, so just think of when someone doubles the CPU threads, then Stockfish needs less time (not necessarily half) to find the solution than it would with the first configuration.

On the first report that was posted on Chess.com someone claimed that Stockfish was not playing optimally because he couldn't reproduce the same results using the same Stockfish on his computer. He said that on the position below (game 1 - move 11) Stockfish played Kg1-h1 (moved its king) which made no sense at all. On the other hand, stockfish on his computer showed a more developing move like Be3 (move the dark square bishop), lets look at the position:

Yes, it was a passive move and it seems that Stockfish should have played a more developing move. But he was wrong. Why? Because he ran Stockfish for 15 seconds, and if he had run it for an hour he would have gotten Kg1-h1 as the best move in that position. Stockfish changes it's decision when it analyses all the possible moves in more depth. Here's what I originally said in my reply:

I ran the latest stockfish on the position (at move 11):

* At first, It gives b4 as the optimal move when the engine is running for about a minute. After that, it decides Be3 is better.
* But after 5 minutes on my hardware that runs on 1,400k nodes/s it will decide to go with Kh1 as the optimal move.
* In the paper, it is said that stockfish calculates 70,000k positions per second and is run for 1 minute per move, that's about 50 times my hardware, so I'll let mine run for 50 minutes... Kg1-h1 is still the choice for Stockfish.

## Time limit is the key

In the above case, it probably didn't matter much if Stockfish ran for twice the time because the decision would have been the same, but on the next move it **definitely would**:

In this position, Stockfish chose to move the pawn on the left side (**a4-a5**). Let's say I have a computer that runs the Stockfish engine at a speed of 1,400k nodes per second, that's about 50 times lower than the Stockfish in the real game (In the paper, it says 70,000k n/s). So I can simulate the game if I run it for 50 minutes at each move. Okay.

I ran Stockfish analysis on the above position and I got the following results:

* Stockfish started out suggesting some moves, but after 6 minutes on my computer (corresponds to **7.2 seconds** on the Stockfish in the real game) **it preferred a4-a5 just as the game went**.

That's good, but I kept it running for a complete 50 minutes in order to reach the computations of the Stockfish in the game that was allowed 1 minute:

The sad truth is that I believe Stockfish lost all its games because of the time limit. Stockfish gets a more in-depth search and evaluation as the time passes and in the game it wasn't allowed to use an opening book which makes it consider many moves in shallow depths. Note that in the actual game *a4-a5* was played which shows that (assuming it could evaluate 70 million positions per second) the Stockfish in the game didn't spend more than 21.6 seconds on the move. Otherwise, it would have changed its decision to those three other moves in the actual game. The reason for this is still unclear to me since my Stockfish was also consuming less memory (about ~130MB of RAM compared to the 1GB mentioned in the original paper, assuming all of it goes to hash tables).

---

## Conclusion

The hardware that ran Stockfish, as I pointed out, was at the very best 18 times faster than mine (Update: on a single core) based on the move I analyzed. I'm not sure if AlphaZero could really make use of such hardware to train its networks in 4 hours, I can only assume it's too low for a game like chess. Besides, AlphaZero spent those hours on learning which also includes building solid openings (and as the paper points out, preferences over certain openings). On the other hand, Stockfish was handicapped on openings, and it did not evaluate 70 million positions per second for 60 seconds on each move.

As a final note, all the things I said were based on my assumptions. Of course, the outcome of AlphaZero and the games were super interesting to me. However, I would have loved to see a game where the Stockfish play was just like what I get on my computer, too. That is, more time and an opening book allowed. It's also easy to get the outputs of Stockfish analysis on every move, and I wish they release it in order to show how well it performed.
> 15 votes

# Answer
One of the original authors of Stockfish answers the specific complaints you mentioned here:

> Meanwhile Chess.com also received a lengthy comment from one of the original Stockfish authors, Tord Romstad, which we'll give in full:
>
> > The match results by themselves are not particularly meaningful because of the rather strange choice of time controls and Stockfish parameter settings: The games were played at a fixed time of 1 minute/move, which means that Stockfish has no use of its time management heuristics (lot of effort has been put into making Stockfish identify critical points in the game and decide when to spend some extra time on a move; at a fixed time per move, the strength will suffer significantly). The version of Stockfish used is one year old, was playing with far more search threads than has ever received any significant amount of testing, and had way too small hash tables for the number of threads. I believe the percentage of draws would have been much higher in a match with more normal conditions.
> >
> > On the other hand, there is no doubt that AlphaZero could have played better if more work had been put into the project (although the "4 hours of learning" mentioned in the paper is highly misleading when you take into account the massive hardware resources used during those 4 hours). But in any case, Stockfish vs AlphaZero is very much a comparison of apples to orangutans. One is a conventional chess program running on ordinary computers, the other uses fundamentally different techniques and is running on custom designed hardware that is not available for purchase (and would be way out of the budget of ordinary users if it were).
> >
> > From another perspective, the apples vs orangutans angle is the most exciting thing about this: We now have two extremely different (both on the hardware and the software side) man-made entities that both display super-human chess playing abilities. That's much more interesting than yet another chess program that does the same thing as existing chess programs, just a little better. Furthermore, the adaptability of the AlphaZero approach to new domains opens exciting possibilities for the future.
> >
> > For chess players using computer chess programs as a tool, this breakthrough is unlikely to have a great impact, at least in the short term, because of the lack of suitable hardware for affordable prices.
> >
> > For chess engine programmers -- and for programmers in many other interesting domains -- the emergence of machine learning techniques that require massive hardware resources in order to be effective is a little disheartening. In a few years, it is quite possible that an AlphaZero like chess program can be made to run on ordinary computers, but the hardware resources required to *create* them will still be way beyond the budget of hobbyists or average sized companies. It is possible that an open source project with a large distributed network of computers run by volunteers could work, but the days of hundreds of unique chess engines, each with their own individual quirks and personalities, will be gone.

Source: https://www.chess.com/news/view/alphazero-reactions-from-top-gms-stockfish-author
> 9 votes

# Answer
Running on comparable hardware would be required if Google's end goal was to build a superior chess engine, but this exercise wasn't really about chess. Chess is just a convenient way to demonstrate the AI's ability to learn complicated tasks from scratch. If it can perform well against some vaguely reasonable configuration of Stockfish, it's checked the box.

I predict the Google team will not spend much more effort on chess; instead, they will move on to other problems that AI has never been able to accomplish.
> 6 votes

# Answer
Visit Talkchess Forum to know more, there is where you will find some 3000 programmers. This was all a scam. Alpha played on 30 times bigger hardware than SF, 4TPUs vs 64 cores. 4TPUs is around 1000 cores or even more. Alpha had simulated opening book, trained on countless top GM winning games. SF had very little hash. TC was fixed at 1 minute per move, which is again detrimental to SF, which has advanced time management. TPUs lack the SMP inefficiencies with more cores, so the hardware advantage was even bigger. Etc, etc., so basically, this was just a huge publicity stunt on the part of Google. Currently, Alpha is around 2800 on single core, so 400 elos below SF, and will not advanced much in the future, as, from now on, it will need advanced evaluation it will not be able to discover. Concerning the 4-hours issue, well, LOL, this was 48 hours ago, so now Alpha is at 5000 elo? Come on.
> 3 votes

# Answer
Stockfish is constrained to CPUs so it will never be able to scale to the level that GPUs are able.

Gor matrix calculations GPUs scale with the n, while CPUs scale with n3, these tensor cores are further optimized so it's likely even better performance as you scale.
> 0 votes

# Answer
First paragraph more detail, second short and simple answer third paragraph my opinions on the situation

With AlphaZero the hardware has 0 effect on the strength of its play. It may take longer but not because it’s thinking. It’s a neural network, which means you feed it info in a vector (a single column table) it does simple math thru a giant tensor (a 3 or more dimensional table) then it spits out the answer. Stockfish needs time to be good because it checks possible positions to see if a move is beneficial, so the longer it looks at the problem the more position/moves it can check.

There isn’t really a comparable hardware setup. Because they have different needs, Stockfish needs to analyze more positions while AlphaZero just needs to make a move. And people are upset because AlphaZero's computer is technically much more powerful and they think they should be equal in that regard. But, AlphaZero doesn’t need that supercomputer after training.

In my opinion it doesn’t matter what they give to either side, unless Stockfish has an unreasonable amount of time it will probably tie a few more games but in general a similar effect will happen. This is why I think this, Stockfish initially evaluates with pieces and their values while, Alpha played (probably) millions of games to realize what is important strategically. Which is why Alpha sacs a lot more than Stockfish would ever, but gains huge positional advantages.
> -2 votes

---
Tags: engines, stockfish, computer-chess, hardware, alphazero
---


title: chess24 castling rules

text:
# Question
Title: chess24 castling rules
Can someone explain to me, why on chess24.com white cannot castle in the situation in the picture? King never moved, neither did either of the rooks. When the queen was moved to `d2` castling was not allowed queenside either. When I take the moves from the game and import to lichess, castling is allowed there. What am I missing?

# Answer
After clicking on the king, the rook is outlined in green, as shown in your both your own image, and mine below.

If you click the rook after clicking the king, castling will occur, shown in the image below:
> 4 votes

# Answer
It seems to be a bug. Lost 2 games today because I could not castle

Edit They changed the way you castle. You have to click on the rook now.
> 3 votes

---
Tags: rules, castling
---


# Question
Title: What is the average length of a game of chess?
I hope this is an appropriate question for this site as I've been wanting a reputable answer. Of course the length of games can vary wildly, but what is the expected number of moves until either a checkmate or trivial draw position is reached? Preferably the answer will be backed by some evidence and is not just "40 moves" like every other internet source.

# Answer
**EDIT:** I opened Mega Database 2012 and found there were 515539 games ranging from the 1400s to 2011. As I couldn't find an efficient way to parse the data, I just used the median move value (I hope it's normally distributed. It's probably not though as the largest number of moves was 277... oh well). The median value was 37 moves, but I'm sure that it's a right-skewed distribution given the max value. If I had to hazard a guess to the average value, I'd put it slightly greater than 40 :)

In addition, keep in mind that these are all *recorded* games. This means that their origin can be from tournaments, matches, or even online competitions. Indeed, the 277 move game was played in a tournament on the Internet Chess Club.

---

Oddly enough, I found that the average length of a game (played by humans) is roughly 40 moves. Based on the statistics provided by the Chessgames database (685,801) games, the average number of moves is 40.04. Chessgames tends to only include player games of a high caliber, so this doesn't really take into account amateur tournaments. As these games are played by humans, few of them tend to end in checkmate but rather a draw by mutual agreement or a resignation in a lost position.

This may not be the best source, but I've played in over 320 tournaments in my life and many of these games are imported into my personal database. The average number of moves per game is around 38.

I do not have access to my Mega Database 2012 (a database provided by Chessbase) at the moment, but I will post the average number of moves of approximately 5 million historical games when I open it.
> 42 votes

# Answer
I did this graph based on 731,000 games played on the free internet chess server by players with rating above 2000 during the last 13 years with **non-blitz time controls**. The **average length is 79 half moves**, the **median is 70** and the **mode is 51.** There are also a lot of very short games due to people resigning early.

**Update:** As it turns out, the above curve can be very well approximated by a log-normal distribution. That is the logarithm of the games lengths are normally distributed. We can then consider the expected game length remaining given how many moves have already been played, which may be interesting for chess engines. It looks like this:

If you want to use it for figuring out how to use your time(\*), the function can be very well approximated by the following expression. (Again remember, that the result is in half moves.).

`59.3 + (72830 - 2330 k)/(2644 + k (10 + k))`

(\*)Though you would probably want to take other factors into consideration as well.
> 44 votes

# Answer
We can make a small analysis from a theoretical point of view:

* Let us call 'n' the number of pieces on the board.
* In a match between players of similar strength, it is expected to find ~n/2 pieces for each side.
* When it is White's turn to move, they have 64-n/2 available squares, n/2 are occupied by rival pieces. That is, fc=(n/2)/ (64-n/2) is the fraction of moves that result in a piece capture
* The same number applies for Black.
* n=32 --\> fc~1/3, at the end of the opening, with pieces fully developed
* n=22 --\> fc~1/5, middle-game
* n=16 --\> fc~1/7, end-game

So, on average, we can expect that each player loses 1 piece every 5 moves approximately. It takes ~8\*5=40 moves to reach a population of 8 pieces vs 8 pieces. After 40 moves, with both "armies" reduced to its half, there is a reasonable expectation that one of them has already lost its king, and so the match is ended.
> 6 votes

# Answer
The average length of chess games depends highly on the reflection time schedule since decisive errors happen very often under time pressure. Cf. https://ingram-braun.net/public/research/parlour-games/article/statistics-length-chessbase/
> 3 votes

# Answer
Sahovski Informator publishes approximately 700 of the Best or Most Interesting games of the preceding several months, played by Grandmasters around the world. I have found the average number of moves in several volumes to converge at between 43 and 44 moves per game. This is, of course, for Grandmasters in tournaments or matches, so they are not giving up easily. Also, interestingly, the number of moves is slowly increasing as time goes forward, indicating perhaps that fewer mistakes are being made, so that games are taking longer.
Also, there is a small variation in length based on the openings - e4-e5; d4-d5; d4-nf6; e4-c5 etc, but it doesn't seem significant.
> 2 votes

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Tags: statistics, database, game-length
---


title: Hitting the clock without moving

text:
# Question
Title: Hitting the clock without moving
In an official blitz game, what happens if a player hits a chess clock without making a move? I believe that making an illegal move in a blitz game is an automatic loss. But does this count as an illegal move because my opponent didn't really make a move?

# Answer
> 12 votes
You can only make an illegal move by making a move. Pressing the clock without moving is not making a move. So the arbiter can't use that rule to make a decision.

There is FIDE rule 6.13 (chapter 6 is about the clock): "If an irregularity occurs and/or the pieces have to be restored to a previous position, the arbiter shall use his best judgement to determine the times to be shown on the clocks. He shall also, if necessary, adjust the clock’s move counter."

So the arbiter can use his best judgement to reinstate the correct clock times. This is of course unfortunate (it's hard to stay concentrated for the players, especially the innocent player), but the arbiter can't just invent rules.

If this happens regularly (the player is doing this on purpose), there is always article 12.8: "Persistent refusal by a player to comply with the Laws of Chess shall be penalised by loss of the game. The arbiter shall decide the score of the opponent."

# Answer
> 11 votes
The rules changed in 2017 to make this an illegal move. Article 7.5 of FIDE Laws of Chess talk about illegal moves, and now Article 7.5.3 mentions this exact case:

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

# Answer
> 3 votes
Per E.I.01B. Appendices - B.3/c

> An illegal move is completed once the opponent’s clock has been started. The opponent is entitled to claim a win before he has made his own move. However, if the opponent cannot checkmate the player’s king by any possible series of legal moves, then the claimant is entitled to claim a draw before he has made his own move. Once the opponent has made his own move, an illegal move cannot be corrected unless mutually agreed without intervention of an arbiter.

# Answer
> 3 votes
There have been recent (1/1/2018) changes to FIDE's rules that relate to this question.

Previously, in blitz/rapid a player making an illegal move would instantly lose the game.

However, January 1, 2018 revisions to FIDE Laws of Chess acted "to equalize the rules for classical chess on the one hand, and rapid and blitz on the other, with regard to the penalty for making an illegal move."

> Before, in both rapid or blitz an "illegal move" (which includes moving with two hands, or not making a move and pressing the clock) would instantly lose the game in case the arbiter intervened or the opponent stopped the clock. Now, in the first instance it will lead to a time penalty and only if a player does it again, he or she loses—just like in classical chess.

Source for quotes on 1/1/2018 change: Peter Doggers, "New FIDE Laws Of Chess For Blitz, Rapid Still Not Perfect," Chess.com, January 3, 2018.

# Answer
> 2 votes
You are correct in saying that in blitz, an illegal move loses the game. In this case, an illegal move is made because your opponent did not move. Hence, if you correctly stop the clock and make a claim to the tournament director, you win the game.

I feel that this would have to be intentional though. I'm not sure what would happen if your opponent accidentally brushed the clock or something. I suppose the decision would be left up to the arbiter.

---
Tags: rules, illegal-move, chess-clocks
---


# Question
Title: confused about a move played by a grandmaster
In this site :

https://www.365chess.com/game.php?gid=2941895

I saw a game between two chess professional players :

**Efimenko, Zahar (2566) vs. Kaliuzhny, Andrey (2213)**

```
[fen ""]
1. e4 d6 2. d4 Nf6 3. Nc3 g6 4. Be3 Bg7 5. Nf3 c6 6. h3 O-O 7. Qd2 b5 8. Bd3 Nbd7 9. O-O e5 10. dxe5 Nxe5 11. Nxe5 dxe5 12. Bc5 Re8 13. a4 Nd7 14. Be3 b4 15. Ne2 a5 16. c3 Rb8 17. cxb4 Rxb4 18. Qc2 Nf8 19. Rfd1 Ne6 20. Qxc6 Bd7 21. Qc2 Qb8 22. Bc4 Rxb2 23. Qc3 Rc8 24. Rxd7 Rxe2 25. Rad1 Bf6 26. Qd3 Rb2 27. Rxf7 Rxc4 28. Rxf6 Qe8 1-0

```

In move 12 , efimenko which is white played **Bc5** which I could not understand :

So I have two questions

1) why he did not play 12 . **Bh6** , instead of Bc5 , to get rid of the dark square bishop on **Bg7**

which protects the king ? and 2) what is the reason of playing **Bc5** ?

I am really confused and I do not understand . Help

# Answer
We can note a few things about the position before Bc5 was played on move 12. First of all, white's dark squared bishop is both his good bishop (due to the fixed pawn on e4) and an active contributor in the position (dissuading black from playing c5 and taking more space in the center/queenside). Moreover, black's dark squared bishop is his bad bishop and is currently blocked in by the pawn on e5. There is not any foreseeable attack on the black king because the knight and light squared bishop are hemmed in by the e4 pawn (and the c6 pawn), there are no open diagonals or files on the kingside, and black has more defenders around his king than white has attackers.

Therefore to answer your first question, Bh6 doesn't make sense in this position. Yes it weakens black's kingside dark squares, but white has no way to ever take advantage of that. You are also willingly trading a good and active bishop with a bad, blocked bishop.

As to why Bc5 was played... that one's a little bit harder. It's basically a high quality passing move assuming black plays perfectly. Bc5 forces Re8, a move that black does not want to play (moving a rook from a closed file to another closed file), so black will have to spend another move later if he wants to activate the rook. But on the other side, the bishop on c5 can be attacked by Nd7, which is arguably not a demotion of the knight. So the bishop will have to return to e3 eventually, effectively trading tempi with black. Maybe white figured that "forcing" black to play Nd7 wouldn't ultimately be useful for black.

Personally, I would be playing 12. a4 and just getting on with it, as I agree it's unclear what white truly gains from this maneuver (especially because we later see that Nf6-d7-f8-e6 is a useful maneuver for black to make).
> 3 votes

# Answer
When I have a question about a GM move, I will look at the board and try to find out why. In this case, I have no idea other than he wants to push a pawn to `a4` but he can't afford the `b4` response. So `Bc5` kicks the `f8` rook with tempo, allowing `a4` for free. But we see black pushes `b4` anyway after using a simple tactic. I prefer `Rfe1` because the pawn on e4 might need some help someday. It's a stock move for me.

So I asked Stockfish. For quite a while it suggested `Bc5` too. Then it switched to Rfd1. The scores it assigned were within a few centipawns of `Bc5`. We see this move starts eyeing ownership of an open file and lines up on the black Queen. We can see simple tactics start happening. After (say) Qe2, then `Bxb5` is possible because of the discovered attack on the Q.

Now that I know this, I can choose other moves and see the response. This will tell me what GM Efimenko was seeing.

(What I can see as I examine moves is that Black wants to play `Be6` and we need to be ready for `Qd7` or `Qc8` threatening the pawn on `h3`. `Be6` is such a nice developing move it is happening regardless of the variations Stockfish is flashing at me.)

My move (`12. Rfe1`) yields a 25 centipawn loss, and the next 4 moves for White are passive pawn moves and rook shuffles. I surmise that while not bad, this move cedes initiative.

How about `12. b4` to stop that `b5` pawn? This move breaks the Queenside open, both bishops to slice into that area, and the rook on `f1` can slide over too. But after `12... a6` Black doesn't have too many problems. Stockfish says this move is also loses about 25 centipawns. I think it gives White a more active game than `12. Rfe1` and if that's the sort of thing you like, it could be ok. One nice thing about this exercise is that I normally would not have considered `b4` at all. And now I found a not-terrible move on my own.

For my last try, I see a lot of the variations White's knight on `c3` gets kicked or is moved to `e2` and black's Be6 move cannot be stopped. What if we accept that and move the Knight first? After `12. Ne2` Stockfish does indeed start a queenside attack, losing maybe 10 centipawns from the preferred move. Stockfish attacks the backward and weak `c` pawn with `Qc3` which cannot be defended adequately. Black drops the pawn on `a7` but White cannot hold onto it. Rolicking and dynamic.

```

[fen "r1bq1rk1/p4pbp/2p2np1/1p2p3/4P3/2NBB2P/PPPQ1PP1/R4RK1 w - - 0 1"]

1. Ne2 Be6 2.Qc3 Rc8 3.Bxa7 c5 4.Bxc5 Nd7 5.b4 Nxc5 6.bxc5 Qe7 7.Bxb5 Rxc5 8.Qb4 Rb8 9.a4 Qc7 10.Rfd1 Rxc2

```

Wow, that really is a lot of "engine" moves. Black has some monster rooks and queen for the pawn.

I probably would have been lame and defended the `c6` pawn. For example, my b-player response might have been `1... Qc7` to defend `a7` and `c6`... While not a bad move, it gives 10 centipawns away (+46 after my move) but avoids the razor-sharp engine moves (as if I could find them).

My next b-player move is the fugly `Bb7`. I would actually not play that because it turns a good bishop into a big pawn. But it does connect the rook and queen. Stockfish thinks it is better than my queen move. This move encourages White to weaken his Kingside with 'f3' to blunt the new pressure against the pawn on `e4`. In a way, this move refutes `12. Ne2`. In retrospect, `Ne2` does indeed remove a defender of `e4`... Who knew, lol!
> 2 votes

# Answer
White wants to play a2-a4 to open lines on the queenside and expose the weak black pawns to attack.

After the immediate 12. a4, play might continue ... b4 13. Ne2 a5 14. c3?! Ba6. Black has counterplay against e4, and is doing well after 15. Bxa6 Qxd2 16. Bxd2 Nxe4. So here White has to delay or omit c2-c3.

After the game continuation, ... Ba6 is not playable, and Black's position is more passive. White has a pleasant initiative.
> 0 votes

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Tags: analysis
---


# Question
Title: I know my mistakes but how would I learn from them?
Learning from your mistakes is the whole point of analyzing your own games is it not? By learning from your mistakes you are able to improve but my question is once I know I played a inaccurate or bad move what can I do about it? Maybe give examples to help me understand?

# Answer
> 10 votes
1. Identify an error - you've done that.
2. Identify a better move - have you done that?
3. Find a memorable difference between 1 & 2.

Step 3 most often involves finding some sort of principle that the better move adheres to. "Exchange when ahead in material" for example. But this is an over simplification. There are different types of errors and they require different responses.

Some errors occur because we are tired or didn't have a good breakfast before the game. Others because we didn't see some tactic and only practicing tactics or chess problems will make significant inroads there.

Sometimes you make an error in the opening. When that happens; find example games where the correct move occurred. Play few a couple of them, find one you like, then memorise it. The whole thing. It's easier than you think and it really helps with opening study.

Strategic errors do seem to require reducing to principles. "I thought exchanging bishop for knight was ok but later I wasn't able to fight my opponents control on the light squares." This situation is difficult. Was the error the exchange or was it the way you played afterwards? Only studying strategy will allow you to judge. Once you make a judgement, trust in it, come up with a way to express why the move is better, some sort of principle that it exemplifies "bishops are stronger than knights if the center is open." And then see how you do.

# Answer
> 4 votes
Well, for a start, you can see what not to play in a given position. Instead, you have to figure out what was the best move and what was the idea behind that move (or perhaps there are several good moves with different motives).

It's not different from any other aspect of life - once you do something wrong, you should remember why it was wrong when you find yourself in a similar situation, so you don't do it again.

But analyzing your game is not just about pinpointing your mistakes - there are often many possible good moves you can play in some position, so try to find them all and try to understand what impact would they have on the game if you played them. While you analyze, after each move you can ask questions like:

* Was this move good?
* What advantages/weaknesses this move produced?
* Perhaps you didn't do a mistake, but was there a better move?
* Or is there some move that is objectively a bit better than what you played, but it doesn't suit your playstyle?
* Or the other way around, perhaps you played a best move and gotten yourself into a problem later on, while instead you could play a move that is a bit worse but it better fits in with your style and you would feel more comfortable with it?
* Was the idea behind the move justified, or you managed to pull off your plan only because your opponent made a mistake?
* Was there any other correct move you could play and what would be advantages of it?

These are just some examples to give you the idea what to think of during analysis. Of course, use some chess engine to help you evaluate the position. Like I said, it's not just about finding mistakes, it's also about finding some other possible solutions and ideas, and also about exposing yourself to some position that could have occured.

The more you are exposed to different positions and you learn what are good and bad moves/motives in it, the better player you will be. Once you learn a lot of possible motives, a lot of good and bad sides of some position, you can apply that knowledge in some other similar situations that will occur in your future games, because those motives and good/bad sides are often shared between similar positions. Also, many patterns are shared even between completely different positions.

The main point is, and that includes learning from mistakes, knowing that you played a bad move and knowing which move would be correct, but it also includes all the other mentioned aspects of understanding the position, analyzing games will ultimately lead to using less time to find more in your future matches.

Now i did a bit of a blunder here and wrote all this text before checking what answers are already available on this site. I will analyze my mistake and perhaps next time I won't write what has already been written somewhere, but in the meantime I hope you can find at least some useful information in this answer. For some other ideas for analysis, try to find some existing questions like this one: How do I analyze my game after playing?.

# Answer
> 2 votes
1. Journal your thoughts
2. What patterns did you miss
3. Invent mental triggers to not miss them again

My only potential contribution beyond what @dsclose said is to maybe expound on his 'step 3'. Also, since I'm \< 1300 USCF, take my thoughts with a grain of salt! :P

---

1. Journal your thoughts

* What patterns did you notice?
    * What moves were you considering?
    * Were you looking really deep in a few areas? Were you looking at all the board?
    * Did you stop calculating the moment you didn't keep forced tempo?
    * Were you having time pressure that changed your thinking?
    * Did you simply feel like you need to be aggressive more?
    * Were you afraid of looking dumb in front of your friends?
    * Did you calculate a move, and then forget (two calculated moves later) that by moving your piece, you left a weakness that undermined your calculated goal?
    * Anything/Everything you were actually thinking!!
2. What patterns did you miss

* I currently believe pattern recognition is %80 of chess. So this post follows that opinion and focuses on pattern recognition the most
    * Look for "pre-patterns." Abstract or concrete patterns that you think correlate to your mistake
    * These are patterns that you can use as triggers later on. That way your pattern recognition catches future similarities *before* your mistakes actually repeat
    * Make up names for the abstract/concrete patterns if you want
    * Use a computer to explore a million lines sometimes
    * made up examples:
    * Did you miss that a piece defending two at once?
    * Did you not take seriously the million ways your king was open to check?
    * Where there "lineups" (pieces in the same line -- even if interposed by other pieces). Maybe that's a more abstract pattern than "pin" that you need to memorize.
    * Was there a knight at one end of the board that *suddenly* was causing forks on the other end? I made up a name called "hop scotch" for that pattern. I tend to be particularly weak in seeing how powerful a knight is, so I prioritize more time looking at 3-4 knight moves first to see if I need to take the knight more seriously. Again, it all depends on what patterns you feel like you are blind to
    * Maybe you suffer from pawn blindness more. Look for pawn patterns. For example: "pawn tension" has three possible outcomes: 1) capture 2) do nothing 3) pawns passing each other. Maybe in your calculations, you forgot that he can simply push his pawn pass yours and not recapture. Maybe that lead to your downfall. In that case, focus on learning very specific pawn patterns and how to react from them.
3. Invent triggers.

* Don't stop once you know "the answer"
    * Don't stop once you know "the generalized answer"
    * You must *actually* change your thinking.
    * Be creative
    * They will be specific triggers to whatever you personally need to learn
    * Ideas:
        + memorize a checklist that you recite before each game. This checklist will be the top, current problems you're working on
        + Make yourself do breathing exercises 10 minutes in (if that's a theme of when you make mistakes most often)
        + Do more chess puzzles (repetition creates stronger pathways "triggers" in your brain)
        + eat more vegetables and do yoga (if your problem is foggy thinking in general)
        + Prioritize patterns. For example, I may have 'felt' like a king was at risk of being exposed, but I ignored it and considered other things (to my regret). So my 'trigger' is this: when I think a king might be exposed, stop *everything* else no matter how good they seem.

---
Tags: analysis, learning
---


# Question
Title: Did any authors ever try to adopt Hans Kmoch's pawn structure terminology?
In response to an earlier question, I mentioned the 1959 book *Pawn Power in Chess* by IM Hans Kmoch. One of the book's most well-known aspects it that it introduced a glut of less-than-useful terminology that is rather more encumbering than enlightening. For instance, Kmoch introduces terms like *dispersion*, *distortion*, *interspan*, *leucopenia*, *melanpenia*, *pincer lever*, *quartgrip*, *telestop* and more that never really caught on. (A further sampling can be found here.)

Ultimately, Kmoch just ends up trying to be too exhaustive, giving names even to things that don't really need them, as far as understanding pawn play is concerned. In the long run, needless to say, this quirky jargon didn't really catch on in the chess literature. But I don't know that it didn't have some impact in the short term. So my question:

> Did any chess books appear, perhaps not too long after the publication of *Pawn Power in Chess*, that did try to adopt some of Kmoch's unusual (and now largely ignored) terminology?

---

By the way, it seems that the Austrian-born Kmoch isn't entirely responsible for this litany of unnecessary terms. An acknowledgement at the beginning of the book reads:

> We wish to express our gratitude to Dr. Walter Meiden of the Department of Romance Languages of the Ohio State University for his careful reading of the English manuscript and for his numerous suggestions both as to subject matter and to style.

You may also know Meiden from *Chess Master vs. Chess Amateur* by Euwe and Meiden.

# Answer
This doesn't quite answer my question, but I find it interesting nonetheless, and think it's worth mentioning. While Kmoch's overload of terminology can serve more to get in the way of a person's understanding than to aid it, one sort of chess player has a very different kind of "understanding" and can actually benefit from Kmoch's taxonomy: chess engines.

Sure enough, the Chess Programming Wiki has an entry on Kmoch, as well as pointers from there to other entries on particular terms from *Pawn Power in Chess*. So that's one place where Kmoch's terms and underlying ideas live on today. (While Kmoch makes no mention of computer chess in his work, it's worth noting that Claude Shannon's pioneering work on the subject had already appeared about a decade before Kmoch's book, so the concept itself was definitely in the air in 1959.)

In any case, my question still stands, as I am after other books written for human players.
> 4 votes

# Answer
I was asking myself who else tried to use Kmoch's terminology; I never find in my books other authors using most of his terms (only some of them).

I am probably the only guy who thinks that the terminology is useful. We all are used to works like "candidates", "Luft", "Zugzwang", "passed pawns", "pawn chain". We could also say that these terms are not completely necessary, as we could always describe what zugzwang or a passed pawn is. Since we are used to these terms, we are happy to use them. We are able to save time when we can use specific terms (instead of explaining them all the time).

The problem is not Kmoch's neologisms, but the fact that he proposed all these terms in one single work. If these terms would be proposed by several authors during decades and slowly adopted by other chess author, we would today use terms like "sneakers" (an unfree pawn or fake that may become a passer through a sacrificial combination) or "wedge" (two converging chains reaching into enemy territory) without thinking about them as neologisms.

New terms are often used in specialized areas, for example in science, to facilitate communication. If you take a dictionary with biological or medical terms, you will probably perceive them as unnecessary - until you begin to work with biology or medicine.
> 7 votes

---
Tags: history, books, pawns, terminology
---


# Question
Title: How to change text color in Arena Chess?
I am trying to create a dark color scheme for **Arena** but the problem is that the text inside the analysis pane – the area below the chessboard – is hard to read. How can I change the color of this text?  I am using Arena 3.5.1 on Windows 7.

# Answer
> 2 votes
It seems that in **Arena** some colors are controlled by the operating system. I went to **Control Panel\Appearance and Personalization\Personalization**, clicked on **Window Color** and in the **Window Color and Appearance** I changed the color of the item **Window** to green in order to make it easier to see the color changes in **Arena**.

And this is the result.

As you can see, some text remained black, like:

* RAM display (next to the Appearance Settings button)
* players' rating
* numbers inside the **Permanent Statistics** pane
* last player move (to the right of opening name)
* the **Demo** button

I don't know how to change the color of these elements.

---
Tags: arena
---


# Question
Title: Do the official rules of chess forbid promoting a pawn to a piece of the opposite color?
Not that it would be everyone's first choice, but it is possible to concoct positions where having an extra piece block your opponent's moves and thus gives you an advantage (think blocking an escape route for a checked king...)

# Answer
Yes.

FIDE Laws of Chess, rule `3.7e`:

> When a pawn reaches the rank furthest from its starting position it must be exchanged as part of the same move on the same square for a new queen, rook, bishop or knight of the same colour.

The Wikipedia article on promotion contains some information about the history of the rule, which previously implicitly allowed promotion to a piece of the opposite color.
> 24 votes

# Answer
While today's official rules do forbid promoting a pawn to a piece of the opposite color, it has not always been the case. I would like to contribute to this topic with a tale in the field of chess humor that stars an alien learning chess. The tail exploits loopholes in the rules and features not only promoting to an opposite-colored piece but also **promoting to a king**:

Elementary, my dear Watson (scroll down to "Yuri Dorogov’s story")
> 4 votes

---
Tags: rules, pawn-promotion, loopholes
---


# Question
Title: What is the thought process of a GM playing bullet?
I have read other posts (e.g. this) with descriptions of the thought process when playing long time controls, but I'm wondering what kind of information a GM processes during games with very short time controls.

# Answer
> 3 votes
Well, of course in very short time controls one cannot assess all the details prescribed in the answers of that good post. Grandmasters rely mostly on their vast experience, as much as it happens in other fields. But we can say that pattern recognition for tactics and mate threats play a major role. And they also learn to polish their intuition. They can efficiently and quickly prune the decision tree (even if they are wrong, they have the process automated) and they learn to recognize the critical points in which they should take some more time evaluating a position. They will have time saved for that critical moment, if it appears.

# Answer
> 2 votes
They look at lots of master games and repeat those same patterns, avoiding blunders.

In the opening, every move is used to get a piece out.

In the middle game, piece maneuvering occurs.

In the end game, they move their kings and rooks to the strongest positions.

There's no shortcut to getting good.

---
Tags: strategy, tactics, positional-play, super-grandmaster, bullet-chess
---


# Question
Title: Why didn't the White queen take the Black rook here?
I was seeing this match on chess.com.

```
[FEN ""]
[StartPly "18"]

1. e4 e5
2. Nf3 Nc6
3. Bc4 h6
4. O-O d6
5. d3 Bg4
6. c3 a6
7. Nbd2 Nf6
8. Qb3 Qe7
9. Qxb7 Nd8
10. Qb3 Be6
11. Qa4+ Bd7
12. Qc2 g6
13. Nb3 Bg7
14. d4

```

The White queen had a chance to take the Black rook, but the White queen came back, why?

# Answer
> 4 votes
I think it's just a blunder from White; the white queen is not at risk of being trapped, nor is it needed for defense. Qxa8 would have definitely been the best move.

Note that the player's ratings aren't that high (no idea how they compare to FIDE ratings though).

---
Tags: rooks, queens
---


title: Python and UCI engine

text:
# Question
Title: Python and UCI engine
I'm working with Stockfish in Python 3.

And when I do something like this:

I get just "bestmove e2e4". How can I retrieve full information?

Like this:

# Answer
> 1 votes
Seems to be working just fine:

```
>>> from subprocess import Popen, PIPE
>>> p = Popen( 'stockfish', stdout=PIPE, stdin=PIPE)
>>> p.stdin.write('uci\n')
>>> p.stdin.write('go depth 10\n')
>>> print p.communicate()[0]
Stockfish 09-06-13 64bit by Tord Romstad, Marco Costalba and Joona Kiiski
id name Stockfish 09-06-13 64bit
id author Tord Romstad, Marco Costalba and Joona Kiiski

option name Use Debug Log type check default false
option name Use 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 (Middle Game) type spin default 100 min 0 max 200
option name Mobility (Endgame) type spin default 100 min 0 max 200
option name Passed Pawns (Middle Game) 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 7 min 4 max 12
option name Max Threads per Split Point type spin default 5 min 4 max 8
option name Threads type spin default 8 min 1 max 64
option name Use Sleeping Threads type check default true
option name Hash type spin default 32 min 1 max 8192
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 200 min 0 max 30000
option name Emergency Move Time type spin default 70 min 0 max 5000
option name Minimum Thinking Time type spin default 20 min 0 max 5000
option name Slow Mover type spin default 100 min 10 max 1000
option name UCI_Chess960 type check default false
option name UCI_AnalyseMode type check default false
uciok
info depth 1 seldepth 1 score cp 76 nodes 28 nps 28000 time 1 multipv 1 pv b1c3
info depth 2 seldepth 2 score cp 12 nodes 166 nps 166000 time 1 multipv 1 pv b1c3 b8c6
info depth 3 seldepth 3 score cp 72 nodes 300 nps 300000 time 1 multipv 1 pv b1c3 e7e5 g1f3
info depth 4 seldepth 4 score cp 12 nodes 692 nps 346000 time 2 multipv 1 pv b1c3 g8f6 g1f3 b8c6
info depth 5 seldepth 5 score cp 64 nodes 1311 nps 655500 time 2 multipv 1 pv b1c3 g8f6 g1f3 b8c6 e2e4
info depth 6 seldepth 7 score cp 12 nodes 4288 nps 857600 time 5 multipv 1 pv b1c3 g8f6 g1f3 b8c6 e2e4 d7d5
info depth 7 seldepth 7 score cp 28 nodes 5522 nps 920333 time 6 multipv 1 pv b1c3 g8f6 g1f3 b8c6 d2d4 d7d5 e2e3
info depth 8 seldepth 8 score cp 12 nodes 9003 nps 1286142 time 7 multipv 1 pv b1c3 g8f6 g1f3 b8c6 d2d4 d7d5 e2e3 e7e6
info depth 9 seldepth 13 score cp 48 nodes 21652 nps 1273647 time 17 multipv 1 pv b1c3 g8f6 g1f3 b8c6 e2e3 d7d5 f1b5 c8d7 e1g1 a7a6 b5c6 d7c6
info depth 10 seldepth 16 score cp 52 nodes 34328 nps 1373120 time 25 multipv 1 pv b1c3 g8f6 g1f3 b8c6 e2e4 e7e5 d2d4 e5d4 f3d4 d7d5 e4d5 f6d5 d4c6 b7c6
info nodes 34328 time 25
bestmove b1c3 ponder g8f6

>>>

```

Don't forget to send `uci` command after loading the engine, so it can initialize all internal stuff and get ready. This is required by UCI protocol.

# Answer
> 2 votes
To get evaluation score for each legal move, you can do:

* Set MultiPV to a high number, like in your answer
* Play the moves, then invoke SF on each of the resulting FEN. For example, in the starting position you could start 20 SF instances, one for each possible move. This is the approach adopted by commercial companies, such as Chessable.

The first approach works but it's slow and not exactly scalable.

PS: Asking for Python code is off-topic here. We can guide you but we won't write code for you.

---
Tags: uci, python
---


# Question
Title: Is it possible to improve by playing mostly blitz?
Can you improve significantly in chess by playing mostly blitz (say, 3 0) games? Or will you eventually reach a wall where the only way to advance is by sitting down for lengthy periods analyzing board positions?

The way I see it, blitz is good because:

* Lots of in-game experience
* Board vision
* Quick tactics practice

What's say chessexchange?

# Answer
Blitz is good for working out the kinks in an opening repertoire and reinforcing themes that you already know, but it won't help if you want to learn new tactics or ideas.

Blitz is too fast to be conducive to figuring out new plans, especially 3 0.

There are some upsides to blitz, though. First and foremost, blitz is fun! If you have 20 minutes, a few blitz games are probably going to be more enjoyable than digging up an old master game and slogging through that. If you go over blitz games afterwards, you'll definitely learn more about your openings as well.

In terms of reinforcing themes and working on tactics, if you make an honest effort during the game to look for the best move and work out the complications (as opposed to just making speculative sacrifices), then yes, it can be useful.

So to summarize, nothing quite compares to going over games between two grandmasters, but blitz isn't terrible. Make sure that when you do end up playing slow games you settle down and think long enough on every move.
> 13 votes

# Answer
Mostly I agree with what everyone else has said. Blitz is great for practicing something you have already, or to just "try it out quickly," but it's not a good way to learn.

In fact, I find that if you play enough blitz you will eventually start getting worse at chess. Your ability to really think through moves diminishes.

So, I would say, treat it like spice. A little here and there is really good, but it should not be your main course.
> 10 votes

# Answer
Most likely, "you eventually reach a wall where the only way to advance is by sitting down for lengthy periods analyzing board positions." This would result from what the economists call the "law of diminishing returns."

But playing blitz should enable you to improve your game for a long time BEFORE you reach that point. That's because it will teach you to think quickly, and think tactically, thereby sharpening your skills in both areas.

Especially if you are a slow, non-tactical player.
> 6 votes

# Answer
In my experience, Blitz will *not* help improve the game significantly.

1. It is fun.
2. It improves slightly to see all the hidden dangers (sacrifices/hidden bishops/etc) as soon as you see the position.
3. It does not guarantee in-game experience because you mostly exploit the mistakes of your opponents under time-pressure and not the positional-game.
4. It is addictive and will be a distraction when you play long regular games and needs to tame/shift your mind to the actual game.
5. Related to 4. It will not help you improve your positional tactical play which requires time and effort to learn.
6. Blitz will ruin your patience and that is one of the important tactics you develop playing chess which will help you elsewhere in life or in other games (poker).

.000000001% Exception: You might be different and can see it differently and can help you.
> 4 votes

# Answer
No, blitz will not help your serious game. You do not have time to analyze in depth, which is the basic necessity to play serious games well. It may be good for trying different opening ideas and sharpening your tactical vision, but not for much else. Most strong players will agree on this. Botvinnik said he played a blitz game once, on a train, and Fischer said blitz kills ideas. Good players can play blitz well, but only after they've spent years honing their skills on slow chess. It does not work in reverse. And yes, analyzing your slow games is the best way to progress.
> 1 votes

# Answer
Blitz will evict overanalysis from your mind. It will teach you to play good moves.

To play great moves, calculation is required. But there's no time in blitz.

Blitz will teach you where to look. Standard will teach you what to do.
> 1 votes

---
Tags: learning, blitz, online, online-blitz
---


# Question
Title: What was the youngest age at which a prodigy could be considered to have been a master?
There is a photo of Reshevsky playing at a very young age (like 8) against many adult players but there were no ratings in those days. I assume that a modern GM who got the title at 12 must have been close to master strength at 8 but I am not sure this is true. I wonder in fact if there is some limitation of the human brain that prevents a certain level of play before a certain age in the same way that no child can run a 4 minute mile, etc.

# Answer
> 4 votes
Let's just say a master is someone who crosses the 2200 USCF mark to get a rough idea. In that case, Abhimanyu Mishra and Liran Zhou both crossed the 2200 barrier around 9 years and 3 months. Christopher Yoo did the same thing in just under 10 years. Note that these chess players did not necessarily reach 2200 strength at those ages, it is likely they were weaker than 2200 but from stochasticity, achieved the crossing. Also note that USCF is the federation associated with United States and 2200 USCF corresponds to something like 2100 FIDE.

---
Tags: rating, children
---


title: Who is better here? [hard]

text:
# Question
Title: Who is better here? [hard]
Who is better in this position? White or black? Hard one!

# Answer
This is indeed an interesting position. I am assuming it is black to move because the highlighted knight move should be the last one, and also because otherwise black would lose their queen for no good reason.

It seems that **white manages to get some compensation by forcing black to exchange their queen for a rook**. However, the evaluation still favors black by a bit less than -2. Anyway, the ending looks very difficult to convert.

This analysis is according to Stockfish 9 at depth 22:

```
[FEN "r2q2k1/pp3Npp/1np1b3/2Q5/3r4/2N5/PP4PP/4RRK1 b Qq - 0 1"]
[Startply "0"]

1... Bxf7 2. Re7 Bc4 3. Qg5 g6 4. Qe5 Qxe7 5. Qxe7 Rd7 6. Qe1 Bxf1 7. Kxf1 Nd5

```
> 2 votes

---
Tags: online-chess
---


title: Slav - Theory Heavy Book

text:
# Question
Title: Slav - Theory Heavy Book
I have come to the realization that studying opening theory is far and away my favorite aspect of chess.

That being said I am looking for a comprehensive theory heavy book on the Slav. I would like one that deals with pawn structure formations, middle game plans, and potentially end games that occur frequently. I would also like one that deals with the subtleties of move order as sometimes that is glossed over in books that are rushed to be published. Any help would be greatly appreciated.

Looking for something aimed at the 2000+ level

# Answer
> 5 votes
http://www.amazon.com/Grandmaster-Repertoire-17-Classical-Slav/dp/1907982388

Grandmaster Repertoire 17 by Avrukh is probably what you're looking for. It is extremely dense and detailed. It will require a lot of work to get all the information that you need, but there are a lot of rewards there as well.

If you have not studied that Slav before, I would recommend:

http://www.amazon.com/Slav-Move-Everyman-Chess/dp/185744678X/ref=sr\_1\_2?s=books&ie=UTF8&qid=1347014456&sr=1-2&keywords=slav+defence

Slav: Move by Move by Lakdawala as it gives a great overview of the plans and ideas of the opening and provides puzzles and quizzes throughout the games to test your understanding.

The Slav is a great opening and I wish you luck in your studies!

# Answer
> 1 votes
The Encyclopaedia of Chess Openings,

https://en.wikipedia.org/wiki/Encyclopaedia\_of\_Chess\_Openings

was (is?) one of the earliest comprehensive theory books when I studied chess in my early days. It seems that these books are still published and updated:

http://www.chessinformant.org/eco-encyclopedia-of-chess-openings

However the analyses in the book might not fully cover all the aspects you are asking for. The included analyses might take you in the right direction though..

# Answer
> 0 votes
Another complete, theory heavy and high quality work on the Slav Defence is "The Complete Slav" by GM Konstantin Sakaev. This series consists of two books, Volume I and Volume II, published in 2012 and 2013 respectively.

---
Tags: opening, theory, books, slav-defense
---


# Question
Title: What is the minimum age to play chess in the senior category?
A senior chess tournament for selection of nationals is happening in our state. I would like to play. What age do I have to be to play in the different senior categories?

# Answer
> 2 votes
FIDE has 2 senior age categories - over 50 and over 65. Most national federations will follow FIDE's lead.

Note that over 50 means that you will be at least 50 years old on the 31st December of that year. So, for over 50 tournaments this year you need to have been born in 1968 or earlier. The reason FIDE do it this way is that they publish your year of birth but not your exact date of birth (for privacy reasons). This information allows organizers to establish whether or not you are eligible.

---
Tags: senior-chess
---


# Question
Title: Android Stockfish communication works differently than on PC?
How is number of threads to use written on **Android** versions of **Stockfish**? Whole communication works but somehow I still can't change number of threads. I even have working code for PC version of Stockfish where changing number of threads works.

This is what I do:

```
SendLine("setoption name Threads value " + threads.ToString());

```

And this is what I get as a reply from Stockfish...

> "Unknown command: setoption name Threads value 3"

When I send the same line with multiPV, Stockfish does everything as expected, sending desired number of PVs.

Is there something to consider when changing number of threads? Something that must be done prior to sending this command? Or is another command expected?

**EDIT:** I checked that when I "later" send meaningless line *'setoption name abc value true'* it returns different text "No such option: abc". While the engine is silent when sending number of threads "later". So I expect it actually works after some time, so my question is, what must be done before sending command to change number of threads? **As on the very initialisation it doesn't work for me.**

# Answer
I'm not sure what exactly happened, but looking through the source code, it appears your first token (`setoption`) is corrupted or not read properly.

Have you modified the code yourself? If so, please revert all your changes. Please double and triple check the source code where you compile Stockfish.

> As on the very initialisation it doesn't work for me.

You don't need to initialise anything to make SF work. The common `uci` is absolutely useless (look in the source code to convince yourself). There is nothing you should need to do to initalize the engine.

I believe the problem was in how you compiled the engine. There's not enough information here for me to give you a complete answer.
> 1 votes

# Answer
Stockfish **ignores** any **first command** I send to him. Don't know why. Probably I do something wrong when I initialize I/O redirection. This works perfectly to me.

```
stockfish.SendLine("Hello Stockfish!");
stockfish.SendLine("setoption name Threads value " + threads.ToString());

```

Just posting this answer as setting up number of threads as first command is quite logical thing to do. Stockfish replying "Unknown command: setoption name Threads value 3" is pretty misleading, taking into account that rest of communication works.
> 0 votes

---
Tags: engines, stockfish, programming
---


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

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

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

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

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

# Answer
> 17 votes
The Site ratings at *slow time controls* **can** be quite reliable for servers where strong players congregate (ICC, FICS to name a few) as the ratings VERY closely reflect your true playing strength if you've played enough games. For very standardized rating systems such as USCF and FIDE/ELO, you will notice that the different rating classes tend to point to the **types of mistakes** those players are still making. NM Dan Heisman's Improving Chess Thinker does an excellent job discussing the types of errors players make across the rating classes.

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

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

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

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

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

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

The spikes are always fun to look at :

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

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

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

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

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

# Answer
> 5 votes
For a very accurate rank of a player's quality, you can use the excellent tool provided by www.chess-db.com. It lets you upload your games and after some minutes it outputs the quality of both players in percentage compared with the best moves of a strong engine.

This is the page to upload a PGN file: http://chess-db.com/public/game\_upload.jsp

And this is an example of the results: http://chess-db.com/public/game.jsp?id=Pablo%20Bento.Shredder%20Android.107755008

# Answer
> 2 votes
chess.com CAPS. Compare CAPS score from chess.com (requires subscription), to table found in a graphic on this: https://www.chess.com/article/view/better-than-ratings-chess-com-s-new-caps-system . Also of interest: https://www.chess.com/article/view/who-was-the-best-world-chess-champion-in-history

Note of caution: Caps scores for anyone particular game are volatile; best to make some average of CAPS scores over a batch of games. Right now, to my knowledge, CAPS can, by extension, predict an Elo rating from a set of moves. Another note: CAPS scores exist in a vacuum without respect to the time controls. I play better chess at slower time controls than I do in a 1-minute bullet game. CAPS will see this difference in play strength and accordingly assign a lower rating to the bullet games. This does not mean that I am not the same person who played the slower time control games!

# Answer
> 1 votes
What you're asking does not exist by my knowledge. However, this is my idea:

You'll need samples with the following features, (1) Chess position, (2) Move made in the position, (3) Rating of the player that made the move.

Let's say you have 1 billion samples. You can train a computer algorithm on these samples that can predict for each move in a position the quality of the move with respect to a rating. All ratings for all moves can be averaged out to get the approximate rating of the player and in effect the quality of his game.

This is a rough idea that can be further polished.

# Answer
> 0 votes
Here are a few ideas on what parameters to measure. Number of blunders per game. How often you have an equal or better position after 10 moves, 15 moves, 20 moves. How often you succeed on using your opponent's blunders. How often you draw or win objectively drawn endgames. How often you succeed to find forced mating combinations. How often you successfully defend objectively lost endgames. How often you lose on time.

---
Tags: analysis, rating, elo, evaluation, performance
---


# Question
Title: Is there any database of every position ever played in a recorded game?
Is there any database of every position ever played in a recorded game? I don't ask of every possible position in chess, or "solving" chess. Only the positions that were played in a recorded game. Ideally, i would like to find for a position how many times it has been recorded to have been played and who won.

# Answer
> 4 votes
> Is there any database of every position ever played in a recorded game

No database is perfect. I would say no for your question.

Sounds like you're looking for the most complete database? I propose:

* Purchase Chessbase Mega Database (many games already!)
* Data mine www.chessgames.com and https://www.365chess.com (you may need a script)
* Download all TWIC games
* Download lichess games
* Download FICS games
* Download MillionBase database

Perform an union operation on all those games.

---
Tags: database
---


# Question
Title: Theory: Things NOT to do in a concrete opening
My sources of opening theory are mostly focuses on things to do in it, and some ideas about why.

What are good sources about things to avoid, and ideas that can't be developed in an opening?

# Answer
This site has some material. Things like don't block your center pawns with your pieces, and don't play into fool's mates, etc.

Then there is a series of beginner-ish books from Pandolfini: Chess Openings: Traps And Zaps

also, Win in the Opening: Opening Mistakes and How to Punish Them by Yakov Neishtadt
> 2 votes

# Answer
Perhaps Taming Wild Chess Openings, written by IM Watson and FM Schiller, is interesting for you. The book contains a collection of bad, dubious and tricky openings. The authors show how to react and, if possible, refute them.
> 0 votes

# Answer
Just look at a bunch of master games (300 or so; maybe 100 per day) and you'll recognize the patterns.

I'd say just look at the first 15 moves and no more. Take no longer than five minutes a game.

When you're really good, you'll be able to take one minute per game. Remember, you're only looking at the first fifteen moves. The patterns are always the same.
> -4 votes

---
Tags: opening, theory
---


title: Which chess rules cover Internet play?

text:
# Question
Title: Which chess rules cover Internet play?
From FIDE Laws of Chess:

> FIDE Laws of Chess cover over-the-board play.

So, which rules cover Internet chess play?

# Answer
> 1 votes
Each individual site will have their own rules, although many of them will be the same.

I haven't played online in years, so I can't list specifics, but I know the rating systems are different from site to site.

# Answer
> 0 votes
I think FIDE Online Arena rules, but I cannot find them in a written form.

---
Tags: online-chess, computer-chess
---


# Question
Title: Database program for statistics about mistakes
I wonder if there is an application that will help with statistics for my own games. Of course - there are applications (eg. Scid, Chessbase) that allow to make some statistics out of database - but it mostly applies to openings. What I would like is to: \- import my games into the app \- run some kind of analysis (with more or less filters) \- get nicely presented statistical output by category

Sample scenario would be - I put all my standard games from 2016, and I want them to be scanned. After that I get report like: \- 40% lost because of tactical blunders \- 90% of draws were when playing black \- in 20% of won games I've reached endgame

It could be in some way done manually - so I could actually annotate the game with simple tags like: 'pawn endgame', 'slav opening' or 'tactical blunder' and put comments of my own or after I've analysed the game with the coach.

My question is - does this kind of application even exist?

# Answer
I've built a web tool (https://www.chessinsights.org/) that you can use to upload your games, filter them, and find mistakes you made. The tool is free and open-source.

I'm currently working hard on adding features. If there's something you really want added, just let me know, and I can work on it.
> 3 votes

# Answer
I do not know of an application that exists, unfortunately. If there was one, people could probably find out and fix their mistakes far quicker than they do now.

The problem is programming an computer to recognize "tactical blunders" or "positional mistakes". It's hard to define in logical terms. Telling a computer to calculate using a point system for pieces and a set of rules is one thing, but teaching it to recognize rather vague concepts is another.
> 2 votes

# Answer
Lichess has something called chess insights which looks a lot like what you want. As pointed out by others, you won't get statistics for something like "lost because of tactical blunders" because it is subjective and difficult to assess computationally.

However there are some useful metrics such as *How often you take advantage of your opponent blunders.*
> 2 votes

---
Tags: analysis, statistics, database
---


# Question
Title: Multiple teams from the same country in Swiss system
Doesn't it create bias for the country?

**Disclaimer**: I realize that benefits of having more teams from the same country far outweigh possible drawbacks, just trying to reason how possibly "unfair" can this be for the other teams, and / if this can be improved.

Imagine last decisive round where two teams from the same country are paired between each other. Will it be a fair match? Does it make sense to avoid such pairings?

# Answer
> 3 votes
There is a tradeoff between making the pairings that "should" be made according to the strict pairing rules, and attempting to prevent collusion. Imagine this scenario:

```
Russia 1: 8.5
Russia 2: 8
India:    8
Peru:     7.5

```

Which is more unfair: to have Russia 1 play Russia 2 and have a possible prearranged result, or to *prevent* Russia 1 and Russia 2 from competing, causing Russia 2 to play a team with a lower score instead of the strong Russia 1 team?

There are several ways to handle this. You could switch the pairings only when it does not cause a team to be moved up or down a pairing group. You could switch the pairings in any round except the last two. Or you could not switch them, and watch closely for signs that the players aren't playing seriously.

---
Tags: swiss-pairing
---


# Question
Title: Is this the correct flow of a chess game?
I am trying to program a chess game as a challenge to myself, however, I am unsure if I have all the moves correct to play a legal game (not any advanced moves, that would be a challenge for another day).

I have created a flowchart/pictorial and text version to depict the flow of the game and the available moves.

The area with a blue background is the main game loop. The area in dark purple are all the possible chess moves.

if there is any part that doesn't make sense or needs clarification please don't hesitate to ask and I will try my best to reword it.

# Game Loop (start move)

### is in checkmate?

* yes
    + lose game
* no
    + threefold repetition?
        - yes
            * stalemate
        - no
            * pawn moved in past 75 moves?
                + yes
                    - stalemate
                + no
                    - has captured in past 75 moves?
                        * yes
                            + stalemate
                        * no
                            + Get all available pieces for current player
                                - iterate all pieces
                                    * check pawn moves
                                    * check knight moves
                                    * check bishop moves
                                    * check castle moves
                                    * check queen moves
                                    * check king moves
                                        + change player

# Chess Moves

## Pawn Move

### was last move a pawn?

* yes
    + was it a double move?
        - yes
            * choice
                + capture en passant
                + other choice
        - no
            * other choice
* no
    + is first move?
        - yes
            * check diagonals for enemy?
                + yes
                    - choice
                        * would kill enemy put in check?
                            + yes
                                - check other pieces to move
                            + no
                                - kill enemy
                                    * is on opposite side of board?
                                        + yes
                                            - promote
                        * other choice
                + no
                    - forward 1 empty?
                        * yes
                            + forward 2 empty?
                                - yes
                                    * choice
                                        + would forward 1 put in check?
                                            - no
                                                * forward 1
                                                    + is on opposite side of board?
                                                        - yes
                                                            * promote
                                            - yes
                                                * other move
                                        + would forward 2 put in check?
                                            - no
                                                * forward 2
                                                    + is on opposite side of board?
                                                        - yes
                                                            * promote
                                            - yes
                                                * other move
                                - no
                                    * would forward 1 put in check?
                                        + forward 1
                                            - is on opposite side of board?
                                                * yes
                                                    + promote
                        * no
                            + check other pieces to move
        - no
            * check diagonals for enemy?
                + yes
                    - choice
                        * would kill put in check?
                            + yes
                                - other choice
                            + no
                                - kill enemy
                                    * is on opposite side of board?
                                        + yes
                                            - promote
                        * other choice
                + no
                    - forward 1 empty?
                        * yes
                            + forward 1
                                - is on opposite side of board?
                                    * yes
                                        + promote
                        * no
                            + check other pieces to move

                            ## Knight Move

### forward 2 left 1 empty?

### forward 2 right 1 empty?

### right 2 up 1 empty?

### right 2 down 1 empty?

* would move/kill put in check?
    + yes
        - if checked all moves check next piece
    + no
        - move to available spot

        ### back 2 left 1 empty?

### back 2 right 1 empty?

### left 2 up down 1 empty?

### left 2 down 1 empty?

## Bishop Move

### check all diagonal spaces stopping if there is a piece in its way

* does move put in check?
    + yes
        - check other moves else check other pieces
    + no
        - move to available spot

        ## Queen Move

same as bishop except all cardinal and intercardinal directions.

## Castle Move

### choice

* check all cardinal spaces stopping if there is a piece in its way
    + does move put in check?
        - yes
            * check other moves else check other choice
        - no
            * move to available spot
* has moved?
    + yes
        - check other pieces
    + no
        - has king moved?
            * yes
                + check other pieces
            * no
                + is queenside castle?
                    - yes
                        * is in check?
                            + yes
                                - check other pieces
                            + no
                                - king 1 to queenside castle in check?
                                    * yes
                                        + check other pieces
                                    * no
                                        + king 2 to queenside castle in check?
                                            - yes
                                                * check other pieces
                                            - no
                                                * is adjacent spot towards king free?
                                                    + yes
                                                        - would put in check?
                                                            * yes
                                                                + check other pieces
                                                            * no
                                                                + move king 2 towards queenside castle, jump castle over king
                                                    + no
                                                        - check other pieces
                    - no
                        * is in check?
                            + yes
                                - check other pieces
                            + no
                                - king 1 to kingside castle in check?
                                    * yes
                                        + check other pieces
                                    * no
                                        + king 2 to kingsidecastle in check?
                                            - yes
                                                * check other pieces
                                            - no
                                                * move king 2 towards kingside castle, jump castle over king

                                                ## King Move

### choice

* has moved?
    + yes
        - can castle? (Note: for the sake of non duplication see arrow)
    + no
        - check other pieces
* check all 1 move in cardinal and intercardinal spaces
    + does move put in check?
        - yes
            * check other moves else check other choice
        - no
            * move to available spot

# Answer
> 2 votes
I don't think it's going to work. Consider this fragment:

You don't "kill enemy" just because your pawn can do the capture. What if your pawn capture exposes your queen behind? What if your pawn capture leads to back-rank mate?

Furthermore, you're not making yourself clear how to choose between moves. Your flowchart implies your program would be making legal pawn moves before considering anything else. This won't work.

You'll have to do searching, something like alpha-beta/nega-max. Your flowchart is way too simple for a reasonable chess engine, if that's your goal.

There won't be any "challenge" from your flowchart. I estimate the program would play no better than a random player. However, if your aim is just to make something that can play a legal chess game; your flowchart is reasonable. It's also a nice mini-project for practising programming.

---
Tags: engines, programming
---


title: How does White crumble Black's center?

text:
# Question
Title: How does White crumble Black's center?
Negi suggests 18.Kh1!N but it seems Black can continue to push his pawns.

```
[FEN ""]
[White ""]
[Black ""]
[Event ""]
[Site ""]
[Result "*"]
[ECO "B33"]
[Date "????.??.??"]

1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5 6. Ndb5 d6 7. Bg5 a6 8. Na3
b5 9. Bxf6 gxf6 10. Nd5 f5 11. Bd3 Be6 12. c3 Bg7 13. Nxb5 Bxd5 14. exd5 Ne7 15.
Na3 O-O (15... e4 16. Qa4+ Kf8 (16... Qd7 17. Bb5 ) ) 16. O-O e4 17. Bc2 Rc8
18. Kh1 (18. Qh5 Rc5 ) (18. f3 Qb6+ $19 ) Rc5 (18... Qb6 19. Bb3 $16 ) 19. f3 Rxd5
20. Qe2 (20. Qb1 Qb8 21. fxe4 fxe4 22. Bxe4 Rh5 {threatening ...d5} 23. Bf3 Rh6
24. Bg4 f5 {The Black center is gone, but Black doesn't stand bad either: White's
Queen and a1 rook are misplaced.} 25. Bh3 $4 Rxh3 26. gxh3 Qb7+ 27. Kg1 Rf6 $19
) Re5 21. Nc4 Re6 22. Bb3 d5 23. Rad1 Kh8 24. Ne3 Rd6 25. fxe4 fxe4

```

Does White just wait for Black to overextend?

# Answer
> 1 votes
Black's pawns might seem impressive, but they're not so easy to mobilize. Clearly, the c3-pawn stops black's d-pawn. Due to the tension by white's pawn f3 on pawn e4, black can't push his f-pawn. And if black pushes e4-e3, the pawn ends up isolated when white plays f3-f4. Therefore, it's often useful for white to keep the tension in the center and to refrain from the exchange fxe4.

In the given main line, after 20.Qe2 Re5, according to Stockfish 9, white has the time to grab the pawn on a6: 21.Bb3 d5 22.Qxa6. White can follow up with Rad1, Nc2, Qe2, f4, after which white is a healthy pawn up and black's center is blocked.

```

      [StartPly "39"]

      [FEN ""]
      1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5 6.Ndb5 d6 7.Bg5 a6 8.Na3 b5 9.Bxf6 gxf6 10.Nd5 f5 11.Bd3 Be6 12.c3 Bg7 13.Nxb5 Bxd5 14.exd5 Ne7 15.Na3 O-O 16.O-O e4 17.Bc2 Rc8 18.Kh1 Rc5 19.f3 Rxd5 20.Qe2 Re5 21.Bb3 (21.Nc4 Re6 22.Bb3 d5 23.Rad1 Kh8 24.Ne3 Rd6 25.fxe4 fxe4) d5 22.Qxa6 Re6 23.Qe2 Rh6 24.Rad1 Qb8 25.f4 Rd8 26.Nb5

```

# Answer
> 1 votes
I have no idea why @Maxwell86 was downvoted. He is correct that Blacks pawns look impressive but it is not easy to see what to do with them. The pawns are strong if they restrict Whites pieces, or if they are mobile enough to generate threats. Neither is the case here. I would regard 16..e4 as a positional blunder, because it fixes the pawn structure, and allows White to form a plan around it. This might be along the lines of Bc2-Bb3 (hold that QP), f2-f4(giving Black a protected passed pawn, but it isnt going anywhere, and White prevents Black from connecting up his Pawns with an eventual ..f4), Na3-c2-e3 (A perfect square, blockading and influencing both wings), Ra1-b1 or Qd1-d2 (protect the b-Pawn) then in due course c2-c4, Bb3-a4, b2-b4, lauching a Pawn avalanche on the Q-side.

Yes, of course Black gets to move also, but I dont see anything like this plan of campaign. White seems to me to have a big advantage because his Pawns are (or will become) mobile and Blacks will not. Whites strategy in this sort of position is always to advance on the Q-side, while Black usually looks for counterplay on the K-side, but this will not be easy with his pawns blockaded. They hardly restrict White from doing what he wishes, and they cant generate threats. It does take time for White to do everything but Blacks play is even slower. White has only one potential weakness (on g2, which the N already protects. Black will try things like Bg7-h6, Rf8-g8, Qd8-f6-g6, Ne7-g6-h4, against which White has Rf1-f2, Qd1-d2.

There is still a game ahead, but it will be the kind of game where each player forms a plan and tries to achieve their own while frustrating the oponent. My money is on White.

---
Tags: opening, 1.e4, sveshnikov
---


# Question
Title: KBN vs K checkmate on nonstandard boards
I know how to win the endgame with bishop and knight, but it is a slippery process and seems to be *just barely* a win, with the enemy king very nearly escaping. For this reason, I am curious about this endgame on other board sizes and if it will still be possible in the general case of an MxN board. Let's assume the 50 move rule doesn't apply.

Here are a few examples.

* Is there a forced win on a 10x10 board?
* Is there a forced win on a 7x7 board, with a bishop of the "wrong"' color (i.e. a bishop that can't attack the corner squares)?

# Answer
Actually, the bishop and knight mate is not as slippery as it appears. I have checked this on a tablebase program I wrote. On a 10x10 board, the side with the bishop and knight (say white) can force mate in at most 47 moves. White can even force mate on a 16x16 board, in at most 93 moves. I believe mate can be forced on an arbitrarily large even size board.

First, on an odd size board, I've confirmed that white cannot force mate if the bishop is on the wrong color. Mate can only be forced in a good corner (one that the bishop controls), so if there are no good corners, mate cannot be forced.

On the 10x10 board, the following is an optimal mate in 47. The starting position is W: Ka1, Nb1, Bc1; B: Kc2. **1.Bb2 Kb3 2.Ba3 Kc2 3.Ka2 Kd3 4.Kb3 Ke4 5.Kc4 Ke5 6.Bg9 Kf4 7.Kd5 Kf5 8.Be7 Kf4 9.Ke6 Kg4 10.Ke5 Kf3 11.Kf5 Kg2 12.Kg4 Kf2 13.Kf4 Kg2 14.Nd2 Kh1 15.Kg3 Ki2 16.Nf3 Ki1 17.Kh3 Kh1 18.Bf6 Ki1 19.Nh2 Kh1 20.Bj2 Kg1 21.Ng4 Kf1 22.Kg3 Ke2 23.Nf2 Kd2 24.Bf6 Ke3 25.Bg7 Kd2 26.Kf4 Kc2 27.Ke4 Kd2 28.Bd4 Ke1 29.Nh1 Kf1 30.Kf3 Ke1 31.Be3 Kd1 32.Ke4 Kc2 33.Kd4 Kd1 34.Kd3 Ke1 35.Ng3 Kd1 36.Bc5 Ke1 37.Bd4 Kd1 38.Bc3 Kc1 39.Nf5 Kd1 40.Ne3 Kc1 41.Kc4 Kb1 42.Kb3 Kc1 43.Be1 Kb1 44.Bd2 Ka1 45.Nc2+ Kb1 46.Na3+ Ka1 47.Bc3#**

This can be played out on apronus.com.

After 23. Nf2, we have a position just like the one shown in Andrew's answer (but upside down: W: Kg3, Bj2, Nf2; B: Ke2). If we make this board 8x8 by removing the a and b columns (and rows 9 and 10), it would be mate in 14, but here it's mate in 25. In the optimal line above, the black king never really tries to escape towards the a10 corner. Let's say he does, with **23. ... Kd2 24. Bf6 Kc2**. This move shortens the mate by one move, with the continuation **25.Kf3 Kb3 26.Ke4 Ka4 27.Kd5 Kb5 28.Bd4 Ka4 29.Kc4 Ka5 30.Kc5 Ka6 31.Kc6**.

The black king can only escape as far as a6, and is ultimately still trapped in the good a1 corner. The rest of this continuation is **31. ... Ka5 32.Nd3 Ka4 33.Kc5 Ka5 34.Nb4 Ka4 35.Kc4 Ka5 36.Be3 Ka4 37.Bb6 Ka3 38.Nd3 Ka4 39.Nb2 Ka3 40.Kc3 Ka2 41.Kc2 Ka3 42.Ba5 Ka2 43.Bb4 Ka1 44.Nd3+ Ka2 45.Nc1+ Ka1 46.Bc3#**

Here is the number of moves to force mate on every even sized board from 4 to 16. 4: 15; 6: 22; 8: 33; 10: 47; 12: 64; 14: 78; 16: 93. Note that on any size board there are a handful of positions that are drawn because black can win a piece immediately.

The following is an optimal mate in 92 on a 16x16 board. The starting position is again W: Ka1, Nb1, Bc1; B: Kc2. **1.Bb2 Kb3 2.Bi9 Ka4 3.Kb2 Kb5 4.Kc3 Kc6 5.Kd4 Kd7 6.Ke5 Ke8 7.Kf6 Kf8 8.Kg6 Kg8 9.Bg11 Kf9 10.Kh7 Ke10 11.Kg8 Kf11 12.Bi9 Ke10 13.Kh9 Kd11 14.Kg10 Ke10 15.Bg11 Kd9 16.Kf9 Kc10 17.Ke10 Kc11 18.Ke11 Kc12 19.Nd2 Kd13 20.Ne4 Ke14 21.Nf6 Kf13 22.Kf11 Ke14 23.Ke12 Kd15 24.Kd13 Ke16 25.Ke14 Kd16 26.Nd7 Kc16 27.Ne9 Kb15 28.Kd15 Kb14 29.Bf10+ Kb15 30.Nd11 Ka16 31.Nc13 Kb16 32.Kd16 Ka15 33.Kc15 Ka16 34.Kc16 Ka15 35.Na12+ Ka16 36.Nb14 Ka15 37.Nd13 Ka14 38.Nc11 Ka13 39.Bc13 Ka14 40.Kc15 Ka13 41.Kc14 Ka14 42.Bd12 Ka13 43.Na10 Ka12 44.Kc13 Kb11 45.Nb12 Ka12 46.Kc12 Ka13 47.Be11 Ka12 48.Bf12 Ka13 49.Bc15 Ka12 50.Nd11 Ka11 51.Bf12 Ka12 52.Nc13 Ka11 53.Kc11 Ka10 54.Nd11 Ka9 55.Nb10 Kb9 56.Kb11 Ka9 57.Kc10 Ka10 58.Bg13 Ka11 59.Be15 Ka10 60.Nd9 Ka9 61.Bh12 Ka10 62.Nc11+ Ka9 63.Kc9 Ka8 64.Nd9 Kb7 65.Nb8 Ka7 66.Kc8 Ka8 67.Bg11 Ka9 68.Be13+ Ka8 69.Nd7 Ka7 70.Bh10 Ka8 71.Nc9 Ka7 72.Kc7 Ka6 73.Kc6 Ka7 74.Bd6 Ka6 75.Bc5 Ka5 76.Ne8 Ka4 77.Kd5 Kb3 78.Kd4 Kc2 79.Bb4 Kb3 80.Kc5 Ka2 81.Kc4 Kb1 82.Kc3 Kc1 83.Nd6 Kd1 84.Kd3 Kc1 85.Nc4 Kd1 86.Ba5 Kc1 87.Bd2 Kb1 88.Kc3 Ka2 89.Kc2 Ka1 90.Kb3 Kb1 91.Na3+ Ka1 92.Bc3#**

It is long, but playing through it definitely helped convince me that white could force mate on an arbitrarily large board. In the first phase, the white king and bishop can corral the black king while buying tempi for the white knight to catch up. Once the black king is trapped in the bad corner (a16 in this case), it is shuffled down the a-file with very little breathing room. Although the procedure is significantly more complicated than a W maneuver, white appears to always be in complete control.
> 25 votes

# Answer
Let's start with the 7x7 question:

> Is there a forced win on a 7x7 board, with a bishop of the 'wrong' color?

This seems to be the easier of the two questions to answer. First, convince yourself that this is the only mating pattern (the Black king could also be on the dark square immediately to its left).

```
[FEN "8/8/8/8/8/4B1NK/8/7k w - - 0 1"]

```

The key point is that it is not possible for White to force this position. Black's king would have been stalemated on the previous move. Alternatively, if Black's king is moved one square to the left, the only legal move that white could have just played would be to move the bishop onto that diagonal, delivering mate. If this were the case, where was Black's king before that? It would have been on f2 (two to the left, one up). So Black was not forced to move into the corner and could have instead avoided the mate. To conclude, there is no way to force mate in the wrong corner; shortening the board doesn't change this fact.

Now the first question:

> Is there a forced win on a 10x10 board?

In this case, White *will* have a proper corner, but let's assume that White can force the Black king into the wrong corner. n the standard 8x8 board, White has to release the king from the side for a few moves in the process of driving the king to the mating corner. See Wikipedia for a complete tutorial. Here is the normal position when Black flees the edge (temporarily).

```
[FEN "8/2kN3B/4K3/8/8/8/8/8 w - - 0 1"]

```

Black usually plays Kc6, and then after Bd3!, the king has no escape. On a 10x10 board, however, Black could play Kb7, followed by Ka7, and finally, Kz6, as we will call the first file to the left "z". White has no way to get the king and knight over to help prevent the Black king from escaping the bind. So again, it's a good thing that the board is only 8x8, otherwise, the bishop and knight would never get to mate the king!

Disclaimer: I have not proven any of my assertions with tablebases
> 12 votes

# Answer
There are obviously many forced wins on any boards where M and N are at least 8 (including M or N or both infinite), so long as there is a corner of the same colour as the bishop's square.

If the pieces are all in the yellow tinted sub-board and the black king cannot escape the d10-j4-j10 triangle, the position is also won on the full board, because such positions can be (optimally) won on that sub-board without letting the black king escape the triangle. Similar goes for the green sub-board. The same applies to an MxN board.

But the won positions are by no means restricted to such positions. In the position shown, for example, White can mate in at most 33 moves against any Black defence. There is, of course, a significant percentage of similar positions.

There are not necessarily forced wins if M and or N are too small. For example, there are no checkmate positions on a 1xN board.

There are, strictly speaking, also a relatively small number of forced wins on (sufficiently large, i.e. M,N \> 2, M+N\>6) boards which include no corner of the same colour as the bishop's square but do include a corner of the opposite colour. This includes the 7x7 board with the "wrong" coloured corners you ask about. This is also possible in a "wrong" corner of any board that includes such a corner, e.g. on an 8x8 board.

```
[FEN "7k/8/7K/8/5N2/8/8/7B w - - 0 1"]

1. Ng6+ Kg8 2. Bd5#**

```

There are no wins on a board that includes no corners, i.e. where one or both sides extend indefinitely in both directions.

There are drawn positions on any size of board. This is the general case on boards that have no corner of the same colour as the bishop's square and on boards where one or both of M and N are too small and, I believe, on boards where M and N are both large. Here is one example on an 8x8 board.

```
[FEN "8/8/8/8/3K2k1/8/1B6/7N b - - 0 1"]
[startflipped ""]

1... Kf3

```

Drawn positions are the exception on the standard board (less than 10% of all positions according to the Nalimov EGTB).

But I believe that on a 10x10 board there are also draws by repetition, where the lone king cannot force the capture of a piece, but the side with the pieces also cannot force mate. I think this becomes the general case for large M and N as it obviously is for odd M and N with the "wrong" coloured bishop.

So long as the board contains a corner of the same colour as the bishop's square and M or N remains at 8 or less, but it is not *too* small, mate will still be forcible generally for finite large values of the other and (somewhat irrelevantly) in as many positions as not for an infinite value of the other.

**Edit:**

After reading DanStronger's post, I think my comments on draws by repetition on larger boards are erroneous. These were based on a 45-year-old analysis that I made when I first learned to play the ending (the details of which are now hazy). But I'm inclined to think the analysis was flawed. In that case, the percentage of draws should actually decrease as the board sizes increase.
> 2 votes

# Answer
I think the biggest distinction we can make here is how many moves it will take to mate the king. There is plenty of evidence above that proves it is possible to mate on an almost ainfinitely increasing board (assuming it stays a square and not a rectangular, as to why ai have no idea). In a tournament there is a 50 move rule to prevent needlessly long games. It is possible to mate with this scenario on a 8x8 board within the confines of 50 moves but with little room for error. The bigger the board, the more space you need to corral the King into the corner m which results in 90+ move mates.

To summarize, as long as the board is square (Length=width), then a KBN vs K mate is achievable. I cannot answer if the board is rectangular. aid someone else knows, they can answer that if they want or you could edit you question!
> 0 votes

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Tags: endgame, checkmate, knights, bishops, elementary-mates
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