# Question
Title: Is attempting to capture the king advisable in this position?
This position occurred in a game of quantum chess recently:

**Is trying to take the king with the queen worth the risk?**

My reasoning for this is:

1. If the bishop is on a2, white can take the king and win the game.
2. If the bishop is on f7, the queen cannot capture the king, the rook on b1 is safe, and black is able to move the rook on f5 out of danger.

What line would follow if the king capture fails? Would it be more beneficial to ignore the possible check and take the rook on f5? What would the best line be from there?

---

**Confused?**

You can check out the rules for Quantum Chess, or read the post written by creator Chris Cantwell.

# Answer
Interesting!

Based on probability lets say we the bishop being in a2 is equally probable as being in f7 (principle of superposition, quantum chess rules).

Taking queen with king is blocked if bishop is in f7, which means there is no move occurring in all possible boards. As it is said in the question, rook is moved out of danger. Probability that this occurs is 0.5 and the loss in the game is black becomes stronger than now as the rook is out of danger.

If the bishop is in a2, moving the queen is allowed. White wins, as question states. Probability is again 0.5 and there is no loss for white.

If the rook is taken instead of moving the queen, again black loses the rook irrespective of where the positioned bishop is. This has a probability of 1. In this situation if bishop is in a2, king is in open check and has to move to g1 or h1, either ways white is way too stronger as it has now 0.5 probability for check mate in consequent step. If the bishop is in f7, king is not in open check and black can play at 50% chance rook b7 as queen can't take rook has 50% and in third move rook takes queen 50% giving 0.125 probability for black to gain hand.

On conclusion moving queen has 0.5 probability to win the game and 0.5 probability to lose the strong hold and give black more power.

Whereas taking rook has 0.5 probability to win in next move, and less probability that black gains more power.

This is by the way a crude analysis, for just two more consequent steps, as it is quantum chess, anything can happen as the total number of boards increases $2^n$ times for n steps.
> 2 votes

# Answer
If this was a normal game and the white bishop was on f7, white would have, among other options, a mate in 7 starting with Ba2+. This also collapses the bishops into one so he doesn't have to worry about which of the bishops is real. So you might think that white could simply do this.

But it's not quite that simple. Since this is quantum chess, black could play Rf^g7, which has a 50% chance of blocking the check, attacking the queen, and getting the rook out of danger. White could respond with Bxb1, and now black is in a quandary - if he plays Rxa7 and it works, that proves that his rook is on g7 and not on f5 and white can play Bxh7 and win the game, and if it doesn't work, that proves his rook is on f5 and not on g7 and white can play Qxh7 winning the game. (If I understand the measurement rules correctly, white will know which of these has happened.) So, black can't capture the queen. If he simply moves his king, white can simplify with Qxg7 followed by Bxf5 with an endgame up a bishop and a pawn (in which black will likely clone his king on the dark squares to prevent the white king from safely advancing... and with potential multiple kings it prevents any sort of meaningful opposition... hmm, maybe simplification isn't as good as I thought. But even without simplification, white has won one of the rooks, which is huge.)

If after Ba2+ Rf^g7 Bxb1, black tries something similar to the series of quantum checks I describe later, by starting with R^d2+ Kg3 R^h3+, it doesn't work because of the pin. White can disarm the attack by trying Bxh7, which has a 3/4 possibility of winning outright, and if it doesn't it still measures and fixes the position of black's rook on f5. Black can play R^g7 again, but the position is not the same, and after Bxf5 black loses half a rook and has no quantum checks available.

But black also has the option of Rb^g7. This potentially attacks the white queen, and now white must retreat the queen or correctly guess the location of the rook. But if white guesses wrong, it's a disaster and he loses the queen. So if white wanted to guess, he should have just done so right away, when it didn't involve losing his queen.

So, maybe Ba2 isn't the way to go for white. Let's look at the seemingly simple gxf5. It wins a rook. Black seems to be toast - but, he has some tricks. He can start with R^f1 which may or may not be check, and either taking it or ignoring it gives white a 50% chance at an immediate loss. So, white must respect the threat, and retreats with Kg3. Black can then put a quarter-rook on h3 with R^h3. White responds with Kxh3, and black puts 1/8 rook on h1 with R^h1. White retreats again with Kg3, and black plays R^g5, placing 1/16 of a rook on g5. Now white's king has nowhere that is completely safe. White can try B^g4 to create additional interference - now, black has only a 1/32 chance of Rxg3 winning. But 1/32 is way better than nothing. While black may have better moves, he can force this after gxf5, meaning black has *at least* a 1/32 chance of winning after gxf5.

Black could also attempt to attack the queen instead of the king. After gxf5 R^b7 Qc5 R1^b5 Qf8, black can attempt Rg7, entangling with the f7 bishop. White can now attempt Qg8 with a 3/4 chance of winning, but there's a 1/4 chance that the g7 rook is real, resulting in Rxg8 Bxg8 (we know it's the a2 bishop because of the entanglement) Kxg8 and now you have a 3 pawn vs 2 endgame. In normal chess this would likely win for white, but here it's a tossup. So that line overall has about a 7/8 chance of winning for white. But this line isn't forced.
> 2 votes

---
Tags: analysis, chess-variants
---


# Question
Title: Time/PLY to let engine run for opening analysis
For critical positions in your opening repertoire:

1. How many PLY do you recommend to let the engine run on a single move (referring to a roughly equal position, about +0.15-0.2)
2. How much time does it takes to reach this (obviously depends on various factors, just trying to gauge the reality of other chess players today, non-super users)?

# Answer
> 2 votes
> 1. How many PLY do you recommend to let the engine run on a single move

This will depend on many factors such as the actual position, how you use the engine for opening analysis, etc

If the engine gives a decent advantage (let's say +-2 or so), there is usually not much point in having it calculate down to mate. Other than that opening analysis with an engine is tricky and should certainly not be automated. Engines are useful for pointing out tactical mistakes in openings and can be useful in evaluating midgame/endgame positions that result from some opening lines.

However at least currently you cannot expect engines to give you the absolute best line from say move 5 in any opening. In many openings engines give an evaluation of +0.6 or so even though experience shows that positions are perfectly playable for both sides.

Also human interaction is needed to evaluate how playable the position is for a human: e.g. you might have an equal position where you are required to find 10 only moves or so; this is not what you want to get into.

> 2. How long does it take you time-wise to reach this?

Depends on position, computing power and perhaps other factors.

# Answer
> 1 votes
There is no definite answer.

1. That really depend on how seriously you think you are. Serious player would let a machine run for a whole day for just a single position. Casual players would just run it for about a minute. If your position is quite and equal, you might get the similar moves, so extra computing power would be useless.
2. Again, that could be a minute or that could be a day.

Please note running the machine for hours is generally waste of time if you don't know what you're doing. Serious players don't analyze every position deeply, they know when to do it and when not to do it.

---
Tags: engines, software
---


title: Midgame zugzwang?

text:
# Question
Title: Midgame zugzwang?
I'm aware that sometimes in the endgame, one player is able to create a fortress and is fine with just shuffling their pieces to a draw.

However, in the midgame, with nearly all the pieces still on the board, is it ever advisable to NOT attack or just shuffle your pieces around? What I envision is perhaps a highly closed position where you would need to sac multiple pieces just to create an opening. In this situation, is it preferable to draw?

# Answer
There is the famous Immortal Zugzwang Game, Saemisch vs. Nimzowitsch, where White ended up in a near-zugzwang situation in the middlegame. In the final position, White, even being a Knight ahead, couldn't move a single piece without severe consequences:

```
6k1/3q2p1/p2bp2p/3p1r2/1p1Pp3/3bQ1PP/PP1B1rB1/1N2R1RK w - - 0 1

```
> 13 votes

# Answer
I think you partially answered the question yourself. I can think of 3 scenarios.

1. In very closed positions like this game of Nakamaura against Rybka neither side may be able to improve the position, forcing players to shuffle pieces around. You might even think of slightly more open position, such as a position with blocked pawn chains and one open file, where all entrance squares for the heavy pieces on that file are covered/defended.
2. Some opening lines can end in a position where a player is forced to accept draw by threefold repetition or worsen his position.
3. Also in very symmetric/drawish positions it might be difficult to achieve anything without making concessions.
> 4 votes

# Answer
Another famous example is http://www.chessgames.com/perl/chessgame?gid=1012683.

```

[fen ""]
[White "Alekhine"]
[Black "Nimzowitsch"]
[StartPly "50"]
1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. Bd2 Ne7 6. Nb5 Bd2 7. Qd2 O-O 8. c3 b6 9. f4 Ba6 10. Nf3 Qd7 11. a4 Nbc6 12. b4 cxb4 13. cxb4 Bb7 14. Nd6 f5 15. a5 Nc8 16. Nb7 Qb7 17. a6 Qf7 18. Bb5 N8e7 19. O-O h6 20. Rfc1 Rfc8 21. Rc2 Qe8 22. Rac1 Rab8 23. Qe3 Rc7 24. Rc3 Qd7 25. R1c2 Kf8 26. Qc1 Rbc8 27. Ba4 b5 28. Bb5 Ke8 29. Ba4 Kd8 30. h4

```
> 2 votes

---
Tags: strategy, zugzwang
---


title: Simple Openings for Beginners?

text:
# Question
Title: Simple Openings for Beginners?
I'm a beginner and I don't know any openings - what are the best openings for beginners?

# Answer
I'm going to ignore the "simple" openings and recommend to you good openings for beginners.

It is pretty common for chess instructors to recommend `1 e4` openings to beginners because they tend to be more dynamic and therefore helps beginners improve in their tactical ability.

My following recommendations are in the spirit of fostering tactical and attacking ability.

* Against `1e4 e5`, I recommend the **Italian Game** because you will often get the **Fried Liver Attack** which will help your tactical ability as well as win you many games.
* Against `1e4 c5`, you could play the **open sicilian** though it has a lot of theory if you choose to stick to it. I recommend the **Smith Morra Gambit** which may not be completely sound, but it will give you great attacking chances.

As Black, you will face `1e4` or `1d4` most often.

* `e5` has a lot of theory and white can play many things, so I would recommend either the **caro kann or french defense**.
* Against d4, the **King's Indian Defense or the Benoni**. Those two openings are pretty much the only way for black ensure a dynamic and tactical game against d4. You could try the Dutch defense, but I find it less tactical and difficult for beginners to play with.
> 2 votes

# Answer
There are easy openings, then there are the ones you're going to see. Your question implies you are a near-beginner. Even so, by now, you have seen:

1. The Ruy Lopez. This is probably THE kingside opening to learn. You'll need it on both sides of the board.
2. The Queen's Gambit. This is THE queenside opening. Again, you'll need it on both sides of the board.
3. The Sicilian. Selected by Black in response to e4. You don't have to play it but you better be ready for it.
4. The Fried Liver Attack. You'll see it in blitz. Be ready. As black you'll learn to hate the f7 pawn. He's a weakling.

That being said, don't try to memorize tons of moves. This is a waste of time. I recommend you get familiar with the first few moves and major variations and learn what the variations are about. Thereafter, stick with good opening practices such as developing pieces and castling. Because as sure as I type this, you're going to see someone play something weird on move 3 and you're going to have to deal with it.
> 1 votes

---
Tags: opening, beginner
---


# Question
Title: How does strategy change in the infinite variant of chess?
I've recently become interested in infinite chess (this presentation from Joel David Hamkins \[updated presentation based on the link provided by JDH in comments; significantly more comprehensive than what was originally linked to\] talks a bit about it and some of the interesting mathematical questions). You can find another discussion of the mathematical properties of infinite chess here.

My question is, has this variant been much explored by chess players (as opposed to mathematicians, not that they aren't also chess players)? Are there resources that explain the strategy for infinite chess? Do the principles that guide standard chess play change drastically for the infinite variant, or are they merely extended?

# Answer
Thank you for the question, and for linking to some of my work on infinite chess. You can find additional material on infinite chess on my blog at http://jdh.hamkins.org/tag/infinite-chess/. There are numerous talks, including slides, with infinite chess movies, as well as more detailed research papers and more. I'd be happy to discuss any aspect of that---please go ahead and ask focussed questions about infinite chess.

But in regards to your question, I would agree that most people working on infinite chess are more mathematicians than chess players, and furthermore the central issues seem to be mathematical in nature. Certainly I am more a mathematician than a chess player, although I enjoy a lot of chess (you can play me on ICC, username: JDH).

You ask specifically whether infinite chess has been explored by chess players, as opposed to mathematicians, and the answer to this is yes. My co-author on several of the infinite chess papers, for example, is C. D. A. Evans, US National master, also philosophy PhD candidate at the City University of New York, but not a mathematician. Also, Noam Elkies, professor at Harvard, is also an accomplished chess player who is also a mathematician, and has written on infinite chess.

In my research practice with Cory Evans, I can report that his chess intuition and analysis was invaluable in shooting down and finding flaws in numerous proposed chess positions. But also, it seemed to be an essentially mathematical activity to come up with the various infinite chess positions that illustrate the various high game values and so on. So it was a true collaboration between two fields.
> 5 votes

# Answer
All the normal rules of chess strategy must be completely void. Consider some of the most important ones:

* Material advantage helps to win. Mainly because with more material it's easier to queen a pawn (not available in infinite chess) and because it makes it easier to checkmate the other king. But checkmate is much harder anyway (no board edge to help), and in infinite chess you may have a billion extra knights that are of no use to help defend your king because they're a trillion squares over to the left. In general material will still be useful, but I doubt a queen is going to be much better than a rook.
* The center. In chess, pieces want to be placed where they influence the most squares, and that's usually the center. In infinite chess, there is no center and no square is inherintly better than any other.
* Development. There is no starting position, and no concept of a square that's better than the original square, so no development.
* Pawn structure is an artifact of having two rows of 8 pawns at the start, and a center. Without any of that, all the knowledge we have about pawn structure goes out the window. A pawn may advance a billion squares without ever meeting another pawn, or be blocked by a trillion of them.

And so on, and so on.

I think a study of the strategy of infinite chess would have to start with an analysis of which basic mates are possible (queen, rook and king vs king probably mates, two rooks don't, I guess? Definitely a lone queen and king doesn't, needs an edge).

If you have a lot of pieces, you'd think you'd want to move part of them towards the enemy king, keeping some at home to defend the king. But for queens, rooks and bishops, distances are deceptive -- if the lines and diagonals are clear, they can get to wherever they can possibly get in two moves. Pawns, kings and knights are unimaginably useless in comparison.

I wonder if anything is known about games of infinite chess with more than a few pieces.
> 5 votes

# Answer
I think this is a valid 2-Rook mate on an infinite board. You use one rook as the wall and the other rook to cooperate with K to give KR vs K mate conventionally.

```
[FEN "2R5/3k4/8/8/8/8/8/4R2K w - - 0 1"]

1. Ree8 Kd6 2. Kg2 Kd5 3. Kf3 Kd4 4. Re7 Kd5 5. Kf4 Kd6 6. Rcc7 Kd5
7. Red7+ Ke6 8. Rb7 Kf6 9. Rb6# 1-0

```
> 4 votes

# Answer
There are games of infinite chess being played on chess playing websites which helps lend clarity to this question, and requires the existing answers to be amended and/or revised.

Contrary to some statements in the existing answers, much of the game playing strategy in classical chess is still valid in infinite chess. In particular (1) winning a game depends heavily on achieving control of the squares between White's and Black's pieces, (2) pieces should be developed quickly, by placing them in the ideal square once, and without wasting tempo by moving the same piece more than once, (3) do not bring out strong pieces too early, as they can easily be threatened while the opponent develops his pieces, and strong pieces themselves cannot attack without themselves being threatened, (4) do not sacrifice pieces without a clear and tangible benefit such as achieving a positional advantage, and (5) don't capture pawns or attack if you haven't completed development.

What is new in infinite chess, is that flank attacks need to be considered (attacking the opponent from behind) and defending from such attacks. Also new patterns to achieve checkmate must be devised as trapping the king at an edge or corner is not possible.

Finally, as stated in one of the answers, the central issue of infinite chess being "mathematical in nature" is an opinion. People who have developed the skills to consistently win games deserves equal if not more attention than the ancillary mathematics. Magnus Carlsen is more famous and prominent than the mathematicians who study chess, just as players who excel in winning in infinite chess have developed a more exceptional talent than people who investigate the ancillary concepts and math.
> 0 votes

---
Tags: strategy, theory, chess-variants
---


# Question
Title: Opening theory overlooking simple moves?
What is the most obvious move, (or simple sequence of moves) long overlooked by opening theory in the last 50 years or so, completely changing the evaluation of a well-known position?

EDIT: Well, I mean those cases in which "an unknown amateur from Siberia wrote to the famous chess magazine that White is losing, because after the simple 12...Nxc3, White cannot take back, because of the discovered check..." Are those just urban legends, or they did actually happen? I am curious...

# Answer
> 4 votes
Joe Gallagher says of 22... Kf8 in *Starting out: the king's indian*:

> Vaisser relates how for many years this move was thought to lose because of some erroneous analysis.

Of 25...Qf8 he writes:

> This came as a great shock for Vaisser. According to theory at the time Black was supposed to play 25...Ra6 and lose

```
[FEN ""]
[White "Vaisser"]
[Black "Bauer"]
[Startply "50"]

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. f4 O-O 6. Nf3 c5 7. d5 e6 8. Be2 exd5 9. cxd5 Re8 10. e5 dxe5 11. fxe5 Ng4 12. Bg5 Qb6 13. O-O Nxe5 14. Nxe5 Bxe5 15. Bc4 Bf5 16. Nb5 a6 17. d6 axb5 18. Bxf7+ Kxf7 19. Rxf5+ gxf5 20. Qh5+ Kf8 21. Bh6+ Bg7 22. Bxg7+ Kxg7 23. Qxe8 c4+ 24. Kh1 Qxd6 25. Re1 Qf8 (25...Ra6 26. Re7+ Kh6 27. Qf8+ Kg5 28. Qg8+) 26. Qe5+ Kg8 27. Qd5+ Kh8 28. Qe5+ 1/2-1/2

```

# Answer
> 3 votes
I doubt very much that you can find anything that is both obvious (to the human eye) and new and strong, but a good candidate for the most drastically re-evaluated simple move might be 3..Nf6 against the Lopez.

# Answer
> 2 votes
There are thousands of small evaluation changes, but there's only a few complete turnarounds busting main lines considered good for decades. Two examples come to my mind. First is correspondence game Voss-Zhak 2010, 30.Re6 winning, refuting the old main line of moscow gambit. Also 22.Kf1 from Giri-Shirov 2014 (found earlier in correspondence games) made old main line Sveshnikov almost lost for black. Both these recent games changed theory evaluations seriously.

---
Tags: opening, theory
---


# Question
Title: Why is exposing my queen for capture better in this position (According to computer analysis)?
In one my of my game, the following position appeared (me white):

Computer analysis says that I should have played `Nf3` (exposing my queen being captured by the bishop). In the proposed scenario by the computer, the opponent will play `h3` (capturing my knight) and so I can capture his bishop with my queen.

But another scenario could occur, the opponent will capture my queen with the bishop and I can then play `Nf7` (something like the fried liver) and the opponent moves his queen and I can capture the rook (Or he can capture my queen and I capture the bishop with the rook but in this case he can then move his queen to prevent the somewhat-similar-to fried liver attack). But In such case, I think the opponent is in a better situation: He got my queen and I got a pawn and a rook (or a pawn and a bishop), He can no more castle but he has much more material so he can do well.

So why does the computer says that this is a better move? I tried `h3` to attach the opponent bishops but computer says this is not a good move!

An explanation for why such an analysis is valid is highly appreciated

# Answer
Your description of the computer's suggestions doesn't quite match the position, but if you mean the computer suggests Nxe5, that is correct, as Bxd1 leads to a variation of Legal's Mate.

1. Nxe5 Bxd1
2. Bxf7+ Ke7
3. Nd5#

If, instead,

1. Nxe5 dxe5
2. Qxg4

and white has won a pawn, and has a big lead in development.
> 15 votes

---
Tags: analysis, tactics, knights, queens, pins
---


# Question
Title: Why is `a5` a better move in this position?
I was playing with a friend and we come to the following position (me white):

My friend played `b5` but computer analysis says that this is a mistake and he should have played `a5`. Now, I don't see why is that better?

Can anyone help me please understand why?

# Answer
First, you need to see that in the original position, Black has already a close to winning advantage. Especially the pin on f3 is nasty; it's hard for White to defend the knight now that the bishop is 'offside' and Black can easily attack it with another piece (Qf6).

Both moves (a5 and b5) share the same idea: gaining space on the queenside, with tempo. The move a5 doesn't attack anything but threatens to trap the bishop. The move b5 has a deep tactical refutation involving a (temporary) queen sacrifice:

```
[FEN "r2qkbnr/pp3pp1/2pp3p/4p3/B2nP1b1/2NP1N2/PPP2PPP/R1BQ1RK1 b - - 0 1"]

1... b5 2. Nxd4!! Bxd1 3. Nxc6 bxa4 4. Nxd8 Bxc2 5. Nc6 Bxd3 6. Rd1 Ba6 7. Nd5

```

and White has more than enough compensation for the pawn; center control, space advantage, advantage in development and a better pawn structure. (Immediate tactics on c7 look promising but aren't.)

Black is better off trying to hold on to the queen, but he'll have trouble protecting his king from the dangerous bishop-knight battery:

```
[FEN "r2qkbnr/pp3pp1/2pp3p/4p3/B2nP1b1/2NP1N2/PPP2PPP/R1BQ1RK1 b - - 0 1"]

1... b5 2. Nxd4!! Bxd1 3. Nxc6 Qh4 4. Bxb5 a6 5. Ba4 Bxc2 6. Bxc2 Be7 7. Ba4 Kf8 8. Nd5

```

This is an unbalanced position with chances for both sides; in any case, much less than Black started out with.
> 5 votes

# Answer
After 1...a5, Black has a good attack and can win the exchange. After 1...b5, White doesn't have to retreat, but can create a material imbalance.

```
[FEN "r2qkbnr/pp3pp1/2pp3p/4p3/B2nP1b1/2NP1N2/PPP2PPP/R1BQ1RK1 b kq - 0 1"]

1...a5 (1...b5 2. Nxd4 Bxd1 3. Nxc6 Qh4 4. Bxb5 Bh5 5. Nd5 Kd7 6. Nxa7+ Kd8 7. Nc6+ Kc8 8. Nb6+ Kb7 9. Nxa8 Kxa8) 2. a3 {Forced. This gives the bishop an escape square} b5 3. Bb3 Qf6 {Adding pressure to the pinned f3-knight} 4. Ne2 {An attempt to break the pin and bring a defender to g3} Nxf3+ 5. gxf3 Bh3 6. f4 {Forced} (6. Re1 Qxf3 {This leads to mate}) Bxf1 7. Qxf1

```
> 3 votes

---
Tags: opening, analysis, tactics, middlegame, bishops
---


title: Recording games on the Play Magnus app

text:
# Question
Title: Recording games on the Play Magnus app
I've downloaded the Play Magnus app, and want to record the games (the PGN) I play. There is an option like 'Export game as PGN'(something like that) which allows me to copy the PGN to the clipboard while the game is in progress, but I don't seem to be able to save the PGN of the completed game since a different screen comes up. Can someone help me figure out how to copy the PGN of the **completed game?**

# Answer
Unless I'm misinterpreting the question, this should be possible:

As soon as the game ends (e.g. "You defeated Magnus!" appears at the bottom, if you win for instance), **don't click the arrow at the bottom** (this is what I assume is the different screen that comes up) but instead **click the list icon in the top right corner**. Click "Export game as PGN-File" and the completed game should be copied to the clipboard.
> 3 votes

---
Tags: pgn
---


# Question
Title: Where can I play this 2v2 chess variant online?
There is this chess variant in India and we call it 'Supply'. Its a 2 vs 2 game with 2 boards and 2 players of a team take alternate colors. The standard rules of chess apply, but with one twist. If your team member captures a piece on his board he can give it to you and since you are your teammate's opponent's color, you can introduce that piece on your board and continue playing, while introducing the piece on your board. There are few rules like no checking and no pawn promotion by putting it on the last rank. The first team to get checkmated loses. This mod of chess is really fun. I don't know if people play this outside India, and what it is called. I would like to play it online with my friends. Do you know any place online where I can play this variant?

# Answer
In America, we call this variant Bughouse, although most players allow place mate. Most online chess playing sites do have this variant. Lichess, chess.com, chessclub, freechess, and chess.net.

Another variant is crazyhouse. Here when you capture a piece, it changes color and becomes one of your drop pieces. Unfortunately this also allow place mate.
> 8 votes

---
Tags: chess-variants, online-chess
---


# Question
Title: Pawn promotion to queen of the other color
A Black pawn reached the end of board and Black himself picked it up and placed a White queen on the board. He removed his hand from the piece.

I am not concerned with 'the spirit of the game' but want to know **technically** if this counts as any other break in concentration during a game, and thus a move played to Black's (extreme) disadvantage?

# Answer
Promoting to a piece of the opposite color is an illegal move. Because of the touch move rule, Black must make a different legal move with that pawn, such as promoting to a Black queen. As a penalty for making an illegal move, two minutes are added to White's clock.
> 9 votes

# Answer
The FIDE Laws of Chess state:

> 3.7 e. When a player, having the move, plays a pawn to the rank furthest from its starting position,he must exchange that pawn as part of the same move for a new queen rook, bishop or knight of the same colour on the intended square of arrival.

Thus it is not "a move played to black's (extreme) disadvantage". It is, as dfan says, says an illegal move but only if black has pressed the clock and completed the move. If he has not pressed the clock and the mistake is seen then he must complete a legal move by replacing the white queen with a black piece and pressing the clock. In that case he will suffer no penalty whatsoever and the only disadvantage that perhaps he feels a little foolish for his mistake.

If it is Black's first illegal move of the game the white queen will be replaced by a black queen and the only disadvantage black will suffer is that his opponent will get an extra 2 minutes on the clock. If it is his second illegal move he will lose the game.
> 6 votes

# Answer
That is very interesting, as after over 45 years of playing chess I was watching a 5 minute speed game and in time pressure, the White player promoted a pawn, but to a Black queen instead of a White one and quickly pressed the clock. The opponent grabbed the Black queen and ran it straight down the file to the opposite side and delivered a bank rank mate with the illegal queen. The first player, the promoter of the pawn, was confused and still did not realize what he had done. The other player, always a cheater of all sorts, claimed the queen was his and refused to give up since he lost on time.

We did not have the rules at that time, so I claimed the Queen belonged to the player who promoted despite being the wrong color because the clock had already been pressed. However, the rule is very clear. The other two problems are that it was a speed game and that USA rules sometimes differ from FIDE rules.
> 2 votes

---
Tags: rules, pawn-promotion, illegal-move
---


title: Why is e6 "forced" in this position?

text:
# Question
Title: Why is e6 "forced" in this position?
Larry Christiansen has played and analysed his four games against Chessmaster.

At the 8th move, he shows a different possible continuation and says that `e6` (shown below) is forced for black. I don't see why black would be any worse if another move is played, so why is this forced? For instance, is `g6` not possible?

---

```
[FEN ""]
1. Nf3 c5 2. e3 Nc6 3. c4 Nf6 4. d4 d5 5. cxd5 Nxd5 6. e4 Nf6 7. d5 Nxe4 8. dxc6 Qxd1+ 9. Kxd1 Nxf2+ 10. Ke1 Nxh1 11. Bb5 b6 12. c7+ Bd7 13. Ba6 e6

```

# Answer
White has some nasty threats involving the loose a8-rook and c7 pawn. After 13...g6:

```
[FEN ""]
[StartPly "26"]

1. Nf3 c5 2. e3 Nc6 3. c4 Nf6 4. d4 d5 5. cxd5 Nxd5 6. e4 Nf6 7. d5 Nxe4 8. dxc6 Qxd1+ 9. Kxd1 Nxf2+ 10. Ke1 Nxh1 11. Bb5 b6 12. c7+ Bd7 13. Ba6 g6 14. Bb7 Rc8 {Saving material} 15. Bf4 {Defending the passed pawn} Bg7 {Carrying on with the planned fianchetto} 16. Bxc8 Bxc8 17. Nc3 {White will be able to take the trapped h1 knight soon or even play Ra1-d1-d8#}

```

However, playing 13...e6 allows the black king to attack the c7 pawn, preventing white cramping down like this.

---

N.B. Not checked by an engine. These are just my first impressions.
> 3 votes

---
Tags: theory, tactics
---


# Question
Title: Misplaying (?) the Guicco Pianissimo; is 14. d4 correct?
I recently lost an OTB game against a strong player (USCF) as white in the Guicco Pianissimo and have a few questions about it, especially 14. d4!?. Feedback/criticism are appreciated greatly.

Thanks everyone

```
[FEN ""]
[Event "Local Tournament"]
[Site "?"]
[Date "????.??.??"]
[Round "4"]
[White "Me"]
[Black "Opponent"]
[Result "0-1"]
[WhiteElo "1800"]
[BlackElo "2300"]
[ECO ""]

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.d3 { I generally enjoy playing these positions for white. } 4...Bc5 5.O-O d6 6.c3 a6 7.a4 Ba7 8.Nbd2 O-O 9.b4!? { Do I really have enough time to play this expansive move here? Perhaps it's better to continue by focusing on development. } ( 9.Bb3 { Followed by Nc4 and Be3 is probably the best way to get the dark-squared bishop into the game. } ) 9...Ne7 10.Bb3 Ng6 11.Nc4 b5! { With my pawn on b4, it seems like this advance blocks my position much more severely than it would otherwise. } 12.axb5 axb5 13.Ne3 { Here, I'm not entirely sure if e3 is the best square. } ( 13.Na5 { this move creates some queenside threats, but I'm worried that the knight will become out of play. } ) 13...Nf4 { A nice outpost, since I can't really play } 14.d4!? { Open the position straight away, or wait? I felt that I almost had no strategic ideas left besides playing this move, but perhaps I should attempt to improve my position beforehand. } ( 14.Qc2 Bb7 { I didn't like this method, because I felt paralyzed by the pressure on the e4 square. } ) ( 14.Re1 { Perhaps I should continue preparatory moves like Re1, Qc2/Qd2 and Bb2, anticipating the opening of the position. } ) 14...Qe8 ( 14...Nxe4 15.Qc2 { Doesn't work due to } 15...Nxc3! { So, how would I have actually been able to proceed after 14... Nxe4? } ) 15.dxe5? { I feel that relieving this tension is a mistake. Re1 looks interesting, keeping a lot of tactical ideas alive in the center. } ( 15.Re1 Nxe4 16.Qc2 Bb7 17.Nf5 { Looks like a respectable position. } ) ( 15.Nd5 N4xd5 16.Bxd5 Nxd5 17.exd5 { Also looks interesting, with black's misplaced queen and undeveloped c8-bishop. } ) 15...dxe5 16.Nd5?? { Now here I'm missing a tactic that I should not miss. Being exhausted isn't a perfect excuse, but I was quite physically exhausted during this game. At this point, I also realize that playing Bb2 far in advance would have eliminated these tactics on the a-file. } ( 16.Nd5 ) ( 16.Bb2 { Might still hold an equal battle } 16...Nxe4? 17.Bd5 Nxd5 18.Qxd5 { Forking } ) 16...N4xd5 17.exd5 Bxf2+! 18.Rxf2 Rxa1 19.Ra2 { I don't know what else I can do here besides try to trade the strong rook. } 19...Rxa2 20.Bxa2 Bg4 21.h3 Bh5 22.g4 Bg6 23.d6 cxd6 24.Qxd6 Qd8 ( 24...Qa8 { Makes things easier. } ) 25.Qxd8 Rxd8 26.Kf2 Ne4+ 27.Ke3 Nxc3 28.Bb3 Rd3+ { And the bishop falls. } ( 28...Rd3+ 29.Kf2 Ne4+ )  0-1

```

# Answer
> 1 votes
I haven't played the Italian game in some time, but my thoughts are in the replayer below:

```
[FEN ""]

  1. e4             e5
  2. Nf3            Nc6
  3. Bc4            Nf6
  4. d3 {You said you like these kinds of positions. Given that the first game of yours I analysed started with 1.d4, it may be advisable to stick to a smaller opening repertoire, e.g. always starting with 1.e4. Either way, I think you played the opening fine}             Bc5
  5. O-O {5.Be3 is common in the Italian game, hoping for 5...Bxe3 6.fxe3, strengthening the centre and giving an open file for the rook. But it is a bit double edged, as sometimes black can play Ng4}            d6
  6. c3             a6
  7. a4 {7.d4 is the key advance that you have prepared for, so I'm not sure why you didn't play it} (7.d4 exd4 8.cxd4 Bb6)            Ba7
  8. Nbd2 {The queenside bishop and knight are the worse pieces in the game for you. If you had played 7.d4, then the c3 square may have been available for the knight and the bishop could come to e3 or g5}          O-O
  9. b4             Ne7
 10. Bb3 {It might be an unconventional square for the bishop in the Italian game, but you shouldn't be moving the same 2 pieces over-and-over again. I don't know what your Bb3 and Nc4 plans aimed to achieve} (10.Bb2)            Ng6
 11. Nc4            b5
 12. axb5           axb5
 13. Ne3 {13.Ne3 isn't such a bad move, as long as either Bb2 or Nc2 are played to defend the a1 rook. 13.Na5 doesn't achieve much as the c6 square can't be occupied}           Nf4
 14. d4             Qe8
 15. dxe5           dxe5
 16. Nd5            N4xd5
 17. exd5           Bxf2+
 18. Rxf2           Rxa1
 19. Ra2            Rxa2
 20. Bxa2           Bg4
 21. h3             Bh5
 22. g4             Bg6
 23. d6 {This loses a pawn. I would try 23. Qe2} cxd6 (23...cxd6 24.Nh4 Qc6 25.Nxg6 hxg6 26.Bb2 Qe4 27.Bc1 Ra8 28.Bb3)
 24. Qxd6 {This loses 2 pawns. Preferable is 24. Nh4} Qd8 (24...Qa8 25.Nxe5 Rd8 26.Qb6 Rd1+ 27.Kf2 Rxc1 28.Kg3 Rxc3+ 29.Kh4 Rc2 30.Nxg6 hxg6)
 25. Qxd8           Rxd8
 26. Kf2 {I don't know why you advanced the king into check. I would have tried to activate the dark square bishop with 26.Bg5}           Ne4+
 27. Ke3            Nxc3
 28. Bb3            Rd3+
 0-1

```

**Summary**

1. You didn't misplay the opening other than not playing the d4 break
2. I'm guessing that you have quite a wide repertoire seeing as you pay both 1.e4 and 1.d4. This is fine, but you may want to focus on just one
3. You moved the same pieces (queenside knight and light square bishop) rather than developing the dark square bishop
4. Towards the end there were multiple tactical blunders such as 26. Kf2, rather than 26. Bg5. The game would have still been tough, but those tactics partly stem from never developing the dark square bishop

---
Tags: analysis
---


# Question
Title: Maximum DTC and maximum DTZ in the endgame KRPKRP
What is the maximum DTC and the maximum DTZ in the endgame KRPKRP (rook+pawn against rook+pawn) ?

# Answer
> 3 votes
According to longest checkmates in chess, the longest DTM (depth-to-*mate*) for KRP vs KRP is **112 moves**, starting from this position with white to move:

```
[FEN "8/7P/1K5R/8/1r1k4/8/4p3/8 w - - 0 1"]

```

The analysis ignores the 50 move rule.

Additionally, according to the Syzygy tablebases., the maximum KRP-KRP DTZ is 122 ply.

```
[Title "DTZ 122 Ply"]
[FEN "8/8/8/1P3p2/8/8/2R2r2/k1K5 b - - 0 1"]

```

---
Tags: tablebases, rook-endgame
---


# Question
Title: Slav Defense/Loss to 1800 player: how to improve?
This is a recent OTB tournament game I lost to a player of the same strength as me (1800). My feeling is that I played poor positional chess and continuously failed to capitalize on his suspect play. Any comments/critiques on strategy or tactics are greatly appreciated.

Thanks Everyone

```
[Event "Local Tournament"]
[Site "?"]
[Date "????.??.??"]
[Round "3"]
[White "Me"]
[Black "Opponent"]
[Result "0-1"]
[WhiteElo "1800"]
[BlackElo "1800"]
[ECO ""]
[FEN ""]
[CurrentPosition "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.d4 d5 2.c4 c6 3.Nc3 { My idea with the Nc3/e3 move order is to discourage dxc4 lines... } 3...dxc4 4.a4?! { I feel like this move was played because I wanted to enter my comfort zone. This is a psychological mistake, I think I should've taken the center immediately, right?! } ( 4.e4 b5 5.a4 b4 6.Na2 Nf6 7.e5 Nd5 8.Bxc4 { Looks reasonably strong for white. } ) 4...Nf6 5.Nf3?! { I'm doing it again. Why not just play 5.e4? I would be taking away black's chance to develop ideally with ...Bf5. } 5...Bf5 { Much to my opponents satisfaction, we've now reached a main line. For some reason, I felt more comfortable reaching this main line (that I in fact don't know extremely well) than I did playing 4.e4 or 5.e4. } 6.e3 { My feeling is that 6.Nh4 leads to more interesting play, but I know 6.e3 is theory. } 6...e6 7.Bxc4 Bb4 8.O-O h6?! { Now I believe black is wasting tempo, and I should poised to punish his play. My opinion is that spending a move on h6 to give an extra square for the bishop isn't worth the time. } 9.Qb3!? { I'm thinking that I will have play on the b-file by driving away the bishop on b4. } ( 9.Ne5 { Perhaps this is another viable choice? The knight seems more active on e5 and this is a typical idea in the slav. } ) 9...a5 { I was expecting 9...Qe7, which also defends b7. } ( 9...Qe7 10.Bd2 { And bring the rooks to the center. What's white's plan in this position? I'm not sure it's clear to me. } ) 10.Na2 Na6 { I thought I could easily win a pawn with 11.Bxa6, but I got taken aback by the rook coming to b6. } 11.Bd2? ( 11.Bxa6 Rxa6 12.Nxb4 Rb6 13.Bd2 Qd6 ( 13...Qe7 14.Nxc6 { Here I thought white would be a little better, but 13...Qd6 was the move that concerned me. } ) 14.Ne5! { This is the move that I failed to see. White is simply winning. } ) 11...Nd5! { Here, I realized that I allowed black to fully equalize. } 12.Bxb4 { Trading my bad pieces for his good ones seemed like my best chance here. } ( 12.Bxd5 { Runs into } 12...Qxd5! { And I still think black is equal. } ) 12...Naxb4 13.Nxb4 Nxb4 14.e4? { This is a very bad decision in my opinion. It's both a positional and psychological mistake. I'm trying to complicate matters here and create some sort of winning chances that aren't even here. My idea is to take on e6. } 14...Bxe4 15.Bxe6 O-O { This is the move that I failed to consider. Now I'm simply left with an isolated pawn and not enough control over the d5-square. } ( 15...fxe6 16.Qxe6+ Qe7 17.Qxe7+ Kxe7 18.Rfe1 $16 ) ( 15...Qe7 16.Rfe1 fxe6 ( 16...Qxe6 17.Qxe6+ fxe6 18.Rxe4 $14 ) ( 16...Bxf3 17.Bxf7+ $18 ) 17.Rxe4 $16 ) 16.Bg4 Qd5 ( 16...Bxf3 17.Bxf3 Qxd4 { I figured my best chance was to meet this with } 18.Rfd1 Qf6 19.Rd7 { And try to create counterplay. } ) 17.Qxd5 { I'm honestly not sure if avoiding an exchange gives me any better chances in this type of isolated pawn position. I didn't want to give him extra tempi though. } 17...Bxd5 18.Ne5 { Now I want to eliminate his bishop at all costs. } 18...Rad8 19.Rfd1 { Fighting in slightly worse positions seems like one of the hardest tasks in chess. Now I have to spend my time trying to find ways to liquidate my weak d-pawn at all costs. } 19...Rfe8 20.Ra3 { Finding it hard to develop this rook on the first rank, I lifted it. I don't know what else there even is here. } 20...Be6?! { Why would he play this? I was happy to liquidate his powerful light squared bishop. } 21.Bxe6 Rxe6 22.f4 Red6? ( 22...f6 { I think he can just play this and invade my 2nd rank with an easy game. } ) 23.Nc4!? { I thought that trading my d-pawn for the a-pawn was my best chance. } 23...Rxd4 24.Rxd4 Rxd4 25.Nxa5 b6 26.Nb3 Rd3 { No he's threatening Nc2, and it seems that I'm forced to place my knight on a1. } 27.Na1 Rxa3 { I was thinking that he might try to keep chances with his rook on the board, but maybe this gives me time for regrouping. } 28.bxa3 Nd5 29.g3 Kf8 30.Nb3 Ke7 31.Kf2 Kd6 32.a5 { Undoubling my pawns seems like it has to be the only try. } 32...bxa5 33.Nxa5 Nb6 34.Ke3 Kd5 35.Kd3 c5 36.Nb7 { Perhaps instead I should be advancing with 36. g4 or 36. f5 in order to restrict his chances of creating breakthroughs on the kingside. } 36...c4+ 37.Kc3 Na4+ 38.Kc2 f5 39.Na5 { I didn't know what else there was. } 39...g5 40.Nb7 gxf4 41.gxf4 { Now he has created a path on e4 for his king to win a pawn. At this point, I stopped recording moves because my time was very low. I still feel like I can draw this somehow, but I ended up losing the game. The a-pawn and c-pawn were traded, and black won my f-pawn. Then I for some reason didn't use my knight actively in defense of the f-pawn, and let it advance too far, losing the game. It's hard to play so many moves in a slightly worse position without cracking at some eventual point. I feel like there were many missed opportunities by both sides to punish the other. If it matters for anything, my opponent was young (maybe 10-12 years old), and we had 90 minutes for the game. }  0-1

```

# Answer
> 6 votes
I play the Slav with both colours. If you want to improve your play, check out *The Slav Defense: move-by-move* by IM Lakdawala. My comments are in the replayer:

```
[Event "Local Tournament"]
[Site "?"]
[Date "????.??.??"]
[Round "3"]
[White "Me"]
[Black "Opponent"]
[Result "0-1"]
[WhiteElo "1800"]
[BlackElo "1800"]
[ECO ""]
[FEN ""]
[CurrentPosition "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.d4 d5 2.c4 c6 3.Nc3 (3.Nf3 {This is more popular as it prevents the Winawer counter gambit, 3...e5}) 3...dxc4 4.a4?! {I don't think this is dubious. You can play 4.e4 in Geller gambit style, but you end up in a mainline Dutch position, which is white's best try against the Slav} 4...Nf6 5.Nf3?! {Again 5.Nf3 isn't dubious. You get a mainline Dutch, which is a decent opening. If you had played 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4 then you would also have the choice of 5.Ne5 to recover the pawn, which is becoming quite popular} 5...Bf5 6.e3 (6.Nh4 {Nh4 is playable, but is most effective after black locks the bishop out of the pawn chain with ...e6}) 6...e6 7.Bxc4 Bb4 8.O-O h6?! {8...Nbd7 would have been in book, but 8...h6 doesn't weaken anything either} 9.Qb3!? (9.Qe2 {Your move misplaces the queen. She thematically belongs on e2 to support e4-e5}) 9...a5 ( 9...Qe7 10.Bd2 { This shows why the queen is misplaced on b3 instead of e2 to support e4-e5.} ) 10.Na2 Na6 11.Bd2? ( 11.Bxa6 Rxa6 12.Nxb4 Rb6 13.Bd2 Qd6 ( 13...Qe7 14.Nxc6 { Doesn't this just lose material to 14...Rxb3 15.Nxe7 Kxe7?} ) 14.Ne5! { OP said: This is the move that I failed to see. White is simply winning. } (14...Rxb4 15.Bxb4 axb4 {This looks fine to me.})) 11...Nd5! { If the queen were on e2, then a pawn fork would be in the air} 12.Bxb4 12...Naxb4 13.Nxb4 Nxb4 14.e4? { I don't see what was wrong with developing the rooks to d1 and e1 } 14...Bxe4 15.Bxe6 O-O 16.Bg4 Qd5 17.Qxd5 {In general, the player who playing against the isolani should keep queens on the board, as it scares the king away from becoming a defender} 17...Bxd5 18.Ne5 18...Rad8 19.Rfd1 { I would seriously consider giving up the pawn to play for the initiative, e.g  19.Rfe1 with an aim to penetrate to e7} 19...Rfe8 20.Ra3 { This isn't so bad, as long as the rook ends up on e3 or f3 to attack the king } 20...Be6?! { Why would he play this? Ans: Black is trading off when playing against an IQP. Now he can double rooks and win that pawn soon} 21.Bxe6 {21.Bf3, keeping pieces on the board was better} Rxe6 22.f4? {This doesn't help white at all, as it creates an extra weakness and doesn't activate the a3-rook.} Red6? {22.Red6 isn't a bad move, as it wins material} 23.Nc4!? 23...Rxd4 24.Rxd4 Rxd4 25.Nxa5 b6 26.Nb3 Rd3 { I think Black should have played 26...Rxf4. The position would be resignable for white.} 27.Na1 Rxa3 { Keeping rooks on the board would give white counterchances, so trading was good. The endgame can only be won by black } 28.bxa3 Nd5 29.g3 Kf8 30.Nb3 Ke7 31.Kf2 Kd6 32.a5 32...bxa5 33.Nxa5 Nb6 34.Ke3 Kd5 35.Kd3 c5 36.Nb7 36...c4+ 37.Kc3 Na4+ 38.Kc2 f5 39.Na5  39...g5 40.Nb7 gxf4 41.gxf4   0-1

```

**Summary:**

1. You seem to get muddled with the many choices in the Slav. You can play the mainline Dutch, Geller gambit, Nh4 or Ne5, but not all in one system. Stick to one system and learn it well
2. The queen belongs on e2, not b3, to support e4-e5
3. When playing against an isolated pawn, try to keep pieces on the board. You spent so much time worrying about black's light square bishop that you missed the chance to aim your pieces at the kingside
4. Passive defence with the rooks didn't work because of the knight on b4. This is a key outpost for Black. I would have sacrificed the pawn to gain piece activity with Ra3-d3 or f3

# Answer
> 3 votes
Your analysis is pretty much to the point. I am not a 1. d4 or Slav player, but the opening looks fine to me.

Basically you liked the (sham) sacrifice starting with 14 e4 so much that you ignored the fact that black is not forced to take (15... fxe6). This whole line basically weakened your d4 pawn which is difficult to defend afterwards.

As it is quite obvious around move 20 that you are going to lose the d4 pawn sooner or later, you should have come up with some ideas for counterplay, perhaps along the e-file, and also I would have kept more pieces on the board increasing your chances. If you are down material you need to play actively. Your position at move 26 is the very opposite of that.

27. a5 would allow you to avoid getting the doubled pawn. Black cannot try to win material with 27 ... Nc2 because of the passed pawn.

At some point around move 33 you achieved an equal position which you should not lose. It is not easy to play because black's king is more active and your knight on the rim, but if you can activate your king and get the knight to more active squares (perhaps via c4 or b3 since you got stuck shuffling the knight between b7-a5 later) there should be no danger. Having the remote a pawn vs the c pawn should slightly favor you.

# Answer
> 2 votes
You are a bit too harsh with yourself in the opening phase:

**4.a4** is not the most aggressive line, but it remains a totally reasonnable choice

**5.Nf3** is the right move. Instead, your suggested 5.e4?! fails to 5...e5! and then:

* Taking the pawn with 6.dxe5 Qxd1+ 7.Nxd1 Nxe4 or 6.dxe5 Qxd1+ 7.Kxd1 Ng4 forking f2 and e5 is great for Black.
* The creative 6.Bxc4 exd4 7.Nf3!? dxc3 8.Bxf7+ Ke7 is not enough (I think this is an old Euwe-Alekhine game)

# Answer
> 1 votes
Just one point, in the variation of move 11, you find 13...Qe7 wrong due to Nxc6, but you didn't look at this one move earlier. Instead of 12. Bd2, 12. Nxc6 retains your extra pawn.

How do I add a replayer to my post? is one of the links about using the replayer.

---
Tags: analysis, learning, strategy
---


# Question
Title: How do I get Stockfish to show notes like it does on Lichess?
I want to write a program to stop a chess game if Stockfish decides that checkmate is unavoidable for a player as a learning exercise. I downloaded Stockfish for Mac and it gives what it thinks is the best move but I can't figure out how to get it to show those more specific notes

# Answer
> 1 votes
Stockfish is an UCI chess engine, so you shouldn't mess up with the engine. You will need to write a new chess GUI.

Useful links:

# Answer
> 0 votes
You can't. Stockfish is just a chess engine and engines dont have such functionality.

Those notes are created by Lichess application not by Stockfish. Lichess manipulates engine outputs to deliver sophisticated functionality.

If you like you can develop an application of a chess engine for this kind of feature using Stockfish or any other engine. UCI protocol (which is a standard protocol for engines) can help you developing such application.

---
Tags: software, programming, stockfish, notation
---


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

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

# Answer
> 9 votes
Wikipedia has a history of the stalemate rule. Stalemate being a draw seems to have become more popular in the 15th century, in part due to Lucena

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

---
Tags: history, stalemate
---


# Question
Title: How to use engines to improve my game (weak amateur, not a top player)
Once, I played a game against an amateur player, who played really well. When I asked him where he'd learnt to play that well, he merely said that *he had used Stockfish to reach that level and had had no formal coaching.*

So I got Stockfish and Komodo, the best chess engines, I believe, along with Arena as a GUI. While I clearly see that the engines are really, really good at chess(they beat me easily), in what ways can I use them to improve my game?

To make my question concrete: **what are the ways in which a weak amateur chess player can use chess engines to improve his/her game?** So, not an expert and not a top player.

## My thoughts

I'm not sure of what the answer could be, but maybe it could include something like *using engines to develop a sound knowledge of openings?* That needn't be the answer, though, it's only my speculation.

# Answer
> 3 votes
**Endings**

Far and away the best way to use engines to improve your play and possibly the easiest is to improve your endgame.

For instance: you are learning to mate with K+B+N v K. Set up the position on the board and play against the engine. You have 50 moves to deliver checkmate. The target is 33 for best play from the worst winning start position. Try several times with the engine display switched off. If you are struggling to do this then try once or twice with engine display switched on. This is a bit like cheating but this way the computer can help you correct your mistakes. Then go back to no engine display.

Similarly, you are trying to defend K+R v K+R+P. Repeat as attacker. Again occasionally switch on the engine display to get help.

**Openings**

This is a bit more tricky and requires a lot more work on your part. You need to be able to give the engine your own opening book.

First, build or get a pgn file with the opening lines you want to practice in the format your engine requires. Second, set your opening book to be the opening book for the engine. Third, play against the computer as both black and white so you get to know your opening both from your point of view and that of your opponent so you think also about his ideas. When you are following your "book" you should know because the computer should reply instantly. When you go out of "book" it will start thinking. In your opening you might have opponent's moves that you are frightened of. Play them against the computer and see how it reacts so you can get good ideas how to play against them and not be afraid.

# Answer
> 3 votes
It's super hard to get better using chess engine. Those are only tools to help you verify if your calculation is okay. So let's say:

* You can check if you saw all the variations that may happen after your sacrifice
* You can verify if you calculated that pawn endgame correctly
* You can also analyze your games

**BUT... (!)**

Do not use engines if you want to improve. I swear. The best way, in my opinion (and not only mine) is to **analyze your game YOURSELF.**

Then, you need to draw conclusions. Then you'll know what you need to work on the most.

1. Endgames
2. Openings
3. Calculation

Some great player (don't recall who) said you can learn the most out of endgames. But it really depends how advanced you are, i.e. if you are a beginner - don't spend your time on openings too much. We would need to know more information to help you better.

# Answer
> 2 votes
1. **Sparring against the machine**. Seeing as you have an opponent willing to play at any time, then you can get a lot of practice in. Most engines have a range of settings, 'personalities', and you can set up positions against them. E.g. if you want to practice mating with KQ vs. K, then an engine is a great opponent for that
2. **Analysing your games**. Engines give detailed variations to help you improve your game. For beginner players, engines are best at telling you when you made tactical blunders
3. **Tutorials**. Many engines come complete with tutorials, videos, exercises etc.

# Answer
> 2 votes
**what are the ways in which a weak amateur chess player can use chess engines to improve his/her game?**

**Null moves**: You can (with chessbase, at least), have the engine play a null move. Let's say you are staring at a position and it is your move. You are clueless as to what to do. You force the engine to play a null move for you and look at the resulting moves the engine would like to play (i.e., you basically give the engine 2 moves in a row). In this way, you see 'threats' that you need to consider parrying, and play your parrying move instead of the null move. Rinse and repeat. After a while you learn to identify threats more quickly.

**Opening Verification of recorded games**: Load the game in and review the opening for mistakes. Simple.

**Middlegame improvement**: Replay a position from both sides in the middlegame just after the kings have castled and most of the pieces are developed. Note what plans the computer tries and what plans of yours fail. Rinse and repeat, several times.

**Endgames**: When you reach an endgame, you can replay critical positions from both sides and evaluate your play while learning how to handle such positions. Note what the computer tries and what fails for you.

---
Tags: engines
---


# Question
Title: Has anyone ever played and recorded a full game of Taikyoku Shogi?
I have googled for a little while and found pages and pages of rules and explanations but no documentation. Are there **any** documented games where the moves have been recorded? It's so ridiculous, I don't believe that anyone has ever been able to finish a game, let alone remember all of the piece movements.

# Answer
The answer is yes.
According to jawp article, a game of Taikyoku Shogi was played for Japanese TV show "Tribia-no-Izumi" (=Fountain of trivia), broadcast on 19th May 2004. The game continued 32 hours 41 minutes and 3805 moves before the first player won. This seems to be the first full-recorded game of the variant.
Also, there is a webpage dedicated to Taikyoku Shogi with a playing webservice（大局FLASH, requiring Flash Player）.
> 16 votes

---
Tags: famous-games, shogi
---


title: Chessbase vs Hiarcs for DB management

text:
# Question
Title: Chessbase vs Hiarcs for DB management
I am a Mac user and ChessBase is not available. Instead I purchased Hiarcs. I would like advise as to whether there's added value to ChessBase that should motivate me to install ChessBase on Parallels or even to buy a cheap laptop for this. Note: my question is not related to engine usage as I don't believe that should matter so much, but rather for DB management, meaning availability of DBs, ease of management, etc... Any pointers would be appreciated!

# Answer
By far, ChessBase is the most popular one, it has been there for a long time. But there is other software that can do more or less what ChessBase can do, like Chess Assistant.

When you compare software, you should consider comparing for example Fritz vs. Hiarcs or ChessBase vs. Chess Assistant, because Fritz or Houdini or Rybka are mainly engines with the capability of full game analysis and ChessBase is more of a database with special feature for the pros.

In terms of opening encyclopedia or other products, they could be read with almost any professional chess software. So, no problem here.

Finally, if you are not a professional chess player, any software like Hiarcs, Shredder or even Stockfish with a GUI could help you and you don't need to buy such expensive software.
> 1 votes

---
Tags: software, database, chessbase
---


# Question
Title: In ChessBase 12, when viewing an Opening Tree, why do all the games always stop near move 26?
I have ChessBase 12 64Bit. To create an Opening Tree I do the following steps:

* I click on "Mega Database 2014".
* I filter all the 5.8 millions games like I want (for example, taking only the games where a specific player was White).
* Right click \> Edit \> Select all.
* Right click \> Edit \> Clip or unclip.
* File \> New \> Database \> Save as type: Books (\*.CTG)
* And then I drag the "Clip Database" to my newly created Opening Tree.
* The newly created Opening Tree works fine.

But there is just one problem: all the games always stop near move 26 (sometimes at move 23, sometimes at move 29).

Why is that? And how can I fix this?

.

.

**Edit:**

Both of the current answers are completely incorrect.

I had the confirmation from two other independant people that their opening trees in their ChessBase do **not** stop after a certain number of moves!

They both told me that in order to make an opening tree that doesn't stop after a certain number of moves, we simply had to select "Absolute Length" and then input a big number (100 will work) for the "Length".

See page n°103 of this manual: http://download.chessbase.com/download/pdf/ManualFritz13.pdf

But that's what I have always done, and it doesn't work.

I have tried to input various numbers for the "Length": 5, 10, 15, 20, 30, 40, 50, 100, 200, 400. And surprisingly, no matter what number I put, the opening tree always stop near move 26!

I also tried to pick "ECO-Relative Length" instead of "Absolute Length", and weirdly there was absolutely no difference: the opening tree still stops near move 26.

This means that there really is a big problem, a bug. ChessBase is simply ignoring whether I choose "Absolute Length" or "ECO-Relative Length" and what number I put for the "Length"...

# Answer
> 3 votes
"Move 26" (or thereabouts) is the "midpoint" of most chess games.

Your opening tree application appears to working fine in getting you to the peak or "combustion point" of most games. (That seems to be its purpose.) From there, it's mostly downhill.

# Answer
> 1 votes
well, in terms of chess phase classification, move 20 is really middlegame not an opening, so the tree should be cut somewhere, I think that function should work when you want to see the first 5 or 10 moves of an opening, and then study other main lines, so that is basically a reasonable choice.

---
Tags: opening, software, database, chessbase
---


title: How to save games in ChessBase reader?

text:
# Question
Title: How to save games in ChessBase reader?
I played a very interesting game today, and I entered it in ChessBase reader, along with some comments. I would love to save this game in a database (.cbh) or as a .pgn, but I don't know how. Can you please help me?

# Answer
I found an easy way to save pgns in CBReader. File-\>Publish to WEB-\>One-click publication-\> the browser will open with your game and 'Download PGN' option. Really fast and easy.
> 4 votes

# Answer
It's not possible, in fact in "Chessbase reader", there is the word **reader** which means you can only pgn (or .cbh ...)

If you want to do such thing, my advice is for you to get a copy of the most used software like Chessbase or Fritz. Probably there is some free stuff which are doing the same but I don't know it.
> 3 votes

# Answer
It is not possible to do this in chessbase reader. You can use Arena Chess (free) to do this then transfer this .pgn into Chessbase Reader. Reader allows me to use Chessbase products for training but to evaluate my own games I use Arena.
> 3 votes

# Answer
I would recommend ChessDB which claims to be the best free chess database program out there, although that was in 2007 ;-). It is quite powerful for a free program with the ability to download from TWIC from within the program. Also import from a player's ICC history. You can hook up to UCI interface games engines.

Of course you can save your games into a database but you cannot import Chessbase format. It has good search capabilities for a free program like player reports and search for games with exact position match.
> 1 votes

# Answer
While you cannot save new games with chessbase reader, you can edit and replace existing ones. So what I do is open a .pgn file (I created one and copy and rename it for each tournament) full of empty games and edit these, i.e. double click an empty game, enter the moves and comments, then right click the game in the list and select replace which lets you edit the metadata and writes the game to the .pgn file. Only the site tag seems to be unavailable, but if you edit it manually, cb reader will display it if the tournament name is short enough.
> 1 votes

# Answer
another simple way is to copy and past your game to a text file and save it as a .pgn , later on you can open it on any chess software.
> 0 votes

---
Tags: pgn, database, chessbase
---


title: Chessbase products - difference

text:
# Question
Title: Chessbase products - difference
Since the ChessBase website is rather unclear, I would like help regarding a few issues:

I have a few questions.

1. What is the main differences between the Big Database and the Opening Encyclopedia?
2. Does the Opening Encyclopedia require purchase of ChessBase separately, or is it a program in of itself?
3. Does either of these below products require a DVD player or is there a downloadable version? ChessBase, Big Database, Opening Encyclopedia

# Answer
1. Big Database is a large (6.8 million) collection of unannotated games. Opening Encyclopedia has slightly fewer games (probably games of lower quality are left out), but also contains 6000 opening surveys, 85 000 annotated games, and opening articles from older issues of ChessBase Magazine.
2. It seems Opening Encyclopedia comes with ChessBase Reader 2013 included. This lets you access the whole content of the Opening Encyclopedia, but it doesn't have the full functionality of ChessBase 14. With the Reader you cannot modify the bases or add your own games and analysis.
3. All the products you mention are available to buy and download from ChessBase Shop.
> 1 votes

# Answer
1. I should add that, in addition, those surveys are very useful for chess players at all levels. So, worth a try! Many chess databases are available on the web for free, but surveys are not!
2. Any chess software like Frtiz, Komodo, Houdini can open and read the databases for you. Consider the fact that Fritz is like $50 while ChessBase is more than $100.
3. Yes, all of them are available via download!
> 0 votes

---
Tags: database, chessbase
---


title: PGN with arrows and circles

text:
# Question
Title: PGN with arrows and circles
I recently imported a PGN file that I got from chesscafe.com into lichess.org, and was surprised to see arrows and circles on the board! Looking at the file, I figured that these graphical elements are encoded in comments like this:

```
{[%csl Rd4,Gd5][%cal Rc8f5,Ra8d8,Re8c8] Black will try...}

```

where %csl gives the color and locations of the circles and %cal gives the color, beginning, and end of each arrow.

This doesn't seem to be documented in any PGN spec I've seen, so I suppose it is an extension. My questions are: who introduced this extension, which other software supports it, and is it documented anywhere?

# Answer
> 6 votes
The original PGN standard was created and published in 1994 by Stephen J Edwards. Here is a copy of his original standard: Portable Game Notation Specification and Implementation Guide.

Here it mentions the use of "%" as an escape string:

> There is a special escape mechanism for PGN data. This mechanism is triggered by a percent sign character ("%") appearing in the first column of a line; the data on the rest of the line is ignored by publicly available PGN scanning software. This escape convention is intended for the private use of software developers and researchers to embed non-PGN commands and data in PGN streams.

So, % in the original specification was for "the private use of software developers".

By 2001 this was already being used with Stephen Edwards dropping out from maintenance of the standard as remarked in this supplement for enhanced PGN:

> Steven Edwards, the author, appears unfortunately to be no longer involved with PGN and there is now no defined means of arbitrating and implementing proposed changes. There is also a huge body of software which implements the current standard and would break in various ways if it were changed.

The document's main proposal is the further definition of how "%" should be used for embedding commands in PGN. This was targeted at time commands:

> 3.2 A generalised format for embedding commands in comments. 3.2.1 Position An embedded command may occur at any position in a standard PGN comment, ie between { } . For example: {Optional leading comments \[%clk 1:05:23\] optional trailing comments} where \[%clk 1:05:23\] is the embedded command string.
>
> 3.2.2 Structure The command string is structured as follows.
>
> A leading tag of \[% A command name consisting of one or more alphanumeric characters. A space character. Either a single parameter or a comma delimited list of parameter values. A closing tag of \]

%csl and %cal are relatively new commands following the 2001 extension definition. I found references to their use on the ChessTempo website in their Comment Markup Annotations Chapter 18. PGN Viewer BETA Version

> The PGN viewer supports some special markup that allows arrows, square highlighting and mini-board insertion to be rendered on the board or move list.
>
> Arrows To have a move show arrows on the board when it is played, you can embed the following type of string into a comment on the move: \[%cal Gc2c3,Rc3d4\]
>
> the '\[' and '\] characters are the start and end of the arrow markup. The %cal indicates you are requesting a coloured arrow to be drawn. This example will draw two arrows a Green arrow from the c2 to c3 squares, and a Red arrow from the c3 to d4 squares. The colour letters supported are R=Red, G=Green, Y=Yellow and B=Blue. Square Colouring To have a move highlight squares on the board when it is played, you can embed the following type of string into a comment on the move: \[%csl Ra3,Ga4\]
>
> The %csl indicates you are requesting a coloured square. This example will highlight two squares, a3 will be highlighted Red, and a4 will be highlighted Green. The colour letters supported are the same as used by the arrow annotations.

It looks like Chesscafe and lichess are following this beta version.

---
Tags: pgn
---


# Question
Title: Why doesn't my transposition table improve my move calculation time?
I have an alpha-beta pruning chess AI that I have implemented using chessjs and chessboardjs. Below is my AI algorithm - it includes move ordering on the first two depths, using the boardScore value at that position as the heuristic, and a hash table of past minimizing and maximizing values for FEN strings at different depths, as a transposition table:

```
var minAI = function(depth, alpha, beta) {
  if (minimaxDict[game.fen() + ' [ ' + depth + ' minimizing ]'])
    return minimaxDict[game.fen() + ' [ ' + depth + ' minimizing ]'];
  var options = game.ugly_moves();
  if (depth <= 0 || options.length === 0)
    return boardScore('b', game, depth);
  if (maxDepth - 1 === depth) //only perform move ordering on "shallow" iteration
    orderMoves(options, depth, false);
  var bestMin = 99999;
  for (var i = 0; i < options.length; i ++)
  {
    game.ugly_move(options[i]);
    if (game.in_threefold_repetition())
    {
      game.undo();
      continue;
    }
    bestMin = Math.min(bestMin, maxAI(depth - 1, alpha, beta));
    beta = Math.min(beta, bestMin);
    game.undo();
    if (beta <= alpha)
      break;
  }
  minimaxDict[game.fen() + ' [ ' + depth + ' minimizing ]'] = bestMin;
  return bestMin;
}

var maxAI = function(depth, alpha, beta) {
  if (minimaxDict[game.fen() + ' [ ' + depth + ' maximizing ]'])
    return minimaxDict[game.fen() + ' [ ' + depth + ' maximizing ]'];
  var options = game.ugly_moves();
  if (depth <= 0 || options.length === 0)
    return boardScore('b', game, depth);
  var bestMax = -99999;
  for (var i = 0; i < options.length; i ++)
  {
    game.ugly_move(options[i]);
    if (game.in_threefold_repetition())
    {
      game.undo();
      continue;
    }
    bestMax = Math.max(bestMax, minAI(depth - 1, alpha, beta));
    alpha = Math.max(alpha, bestMax);
    game.undo();
    if (beta <= alpha)
      break;
  }
  minimaxDict[game.fen() + ' [ ' + depth + ' maximizing ]'] = bestMax;
  return bestMax;
}

var bestAI = function() {
  var options = game.ugly_moves();
  if (!options.length) return;
  orderMoves(options, maxDepth, true);
  var bestScore = -99999;
  var moveIndex = -1;
  var alpha = -99999;
  var beta = 99999;
  for (i = 0; i < options.length; i++)
  {
    game.ugly_move(options[i]);
    var moveScore = minAI(maxDepth - 1, alpha, beta);
    if (moveScore > bestScore)
    {
      moveIndex = i;
      bestScore = moveScore;
      alpha = Math.max(alpha, bestScore);
    };
    game.undo();
    if (beta <= alpha)
      break;
  }
  game.ugly_move(options[moveIndex]);
  board.position(game.fen());
  if (game.in_checkmate())
    window.setTimeout(alert("Checkmate!"), 250);
  else if (game.in_draw())
    window.setTimeout(alert("Draw!"), 250);
  else if (game.in_stalemate())
    window.setTimeout(alert("Stalemate!"), 250);
  else if (game.in_threefold_repetition())
    window.setTimeout(alert("Threefold repetition!"), 250);
  else if (game.insufficient_material())
    window.setTimeout(alert("Draw by insufficient material!"), 250);
}

```

Here is my game running on maxDepth = 5 after 5 moves, without the transposition table hash being used. At the bottom of the picture are the setTimeout violations, which (though they aren't supposed to be used as timers) show the time it took for each move to be made.

And here is my game with the transposition table hashing:

Comparing the two move calculation durations, it doesn't look like my transposition table is helping too much, and is sometimes slowing me down. Is my implementation of the transposition table incorrect? Is the move ordering algorithm hampering me in some way?

# Answer
Let's give a try:

* Are you sure your `fen()` is correct? Don't assume, check how many times your TB table is being used. If the `fen()` is bugged, your TB would never be used. A possibility is that you add halfmove clock and fullmove number into FEN (please check).
* Please note the `fen()` function is very **slow**. Your line `minimaxDict[game.fen() + ' [ ' + depth + ' maximizing ]']` is **wrong**, because you are asking the computer to compute the FEN position **twice**. It's important to note computing an FEN position can only be done by looping through the whole board (64 squares). Everytime when we read a square, we must append a character to the existing (possibly immutable) memory array. Appending a character to memory is a **super slow** operation, because the computer might need to allocate new memory. Please ask on Stackoverflow if you want clarification. This is a very **serious** issue. Your TB implementation is meaningless unless you're sure `fen()` is **fast**, and no reallocation complexity.
* Please note a much better implementation is **zobrist** hashing. Why wouldn't you use it?
* Please **check**, double-check and triple-check if your TB is being used. Are you sure `if (minimaxDict[game.fen() + ' [ ' + depth + ' maximizing ]'])` is true? Anything could happen in a program.
* How many times your TB value was returned in the search? 1%? 2%? Do you have a number?
* Your TB has the depth information and min/max. I've never done it myself like this. Are you sure it makes sense?
> 2 votes

---
Tags: engines
---


title: When is a bishop stronger than a rook?

text:
# Question
Title: When is a bishop stronger than a rook?
Usually the rook is stronger than the bishop. Are there situations (and obviously I'm not assuming equal material) in which the latter is stronger?

# Answer
> 5 votes
The standard value for a piece that we learn early on (Queen=9 pawns, Rook=5 pawns, Bishop,Knight=3 pawns) is often a very good guidepost for people to make proper trades and find good tactical sequences. However, it should not be taken for granted that a rook will always be better than a bishop. Let's look at one extreme example:

```
       [fen "rn5k/3p4/p1pP4/PpP5/1P6/8/5B1P/7K w - - 0 1"]

       1.h4 {White wins by using the h-pawn as bait for the black king, and then infiltrate on black's queenside with the white king.} Kh7 2.Kg2 Kg6 3.Kf3 Kf5 4.Be3 Ra7 5.h5 Ra8 6.h6 Kg6 7.Ke4 Ra7 8.Ke5! {White places the king as close to the queenside as possible before sacrificing the h-pawn.} 8...Ra8 9.h7! {Luring the black king away from the defense of the f6 square.} 9...Kxh7 10.Kf6 Kg8 11.Ke7 Kg7 12.Kd8 Kf8 13.Kc8 Ke8 14.Kb7 Kd8 15.Kxa8 Kc8 16.Ka7 {Zugzwang! Black's king has to move, which means that the knight is lost.} Kd8 17.Kxb8 Ke8 18.Kb7 Kd8 19.Kxa6 Kc8 20.Ka7 Kd8 21.Kb8 {and white will win by promoting the a-pawn.}

```

Here white's bishop was stronger than black's rook and knight together, and it's not difficult to realize why; the knight was completely paralyzed, and the rook couldn't get out because of that. Black's pieces were nothing more than a couple of sitting ducks, so to speak.

In general, a piece is only good if it is performing some specific task on the chessboard, such as attacking weaknesses in the enemy camp or defending weak points in one's own camp. If the piece just sits on the edge of the board like a bystander (as in the example above) then it's totally worthless.

The rook is often a very good piece; since it's a long range piece, it can often attack and defend at the same time, and it can easily switch targets if there are many open ranks and files for the rook to move along. The same can be said about the bishop, using diagonals instead of rank and files, but the bishop has a clear disadvantage when compared with the rook: it can only influence squares of one color! Let's look at an example where the rook dominates the bishop, from Grischuk-Radjabov, Corus 2003:

```
    [fen "4k3/5R2/4K3/8/5p2/5P2/3b4/8 w - - 0 1"]

    1.Rc7! {White threatens checkmate in one move, which forces black's king to move.} 1...Kf8 (1...Kd8?? 2.Rd7+ {picks up the bishop for white.}) 2.Kf6 {Threatening mate in one move again. Note how white's rook covers c3 so that the bishop cannot check the white king.} 2...Ke8 (2...Kg8 3.Rg7+ Kf8 (3...Kh8? 4.Kg6 {and black is getting mated shortly.} 4...Bb4 5.Rc7 Kg8 6.Rc8+ Bf8 7.Ra8! {Zugzwang! Black's king has to move.} 7...Kh8 8.Rxf8#) 4.Rd7! {The white rook is hitting the black bishop, as well as it threatens mate in one yet again.} 4...Bc3+ 5.Kf5 {and white wins, since the black bishop is unable to defend the pawn on f4 due to the white rook covering the d2 square.}) 3.Re7+ Kd8 4.Re4! {White's rook cuts off the black king from the kingside, and therefore Radjabov decided it was time to resign in this position.} (4.Re4 Kd7 {For the sake of completeness, this is how white wins if black plays on:} 5.Kf5 Kd6 6.Rxf4! Bxf4 7.Kxf4 Ke6 8.Kg5! {and white has achieved a well known winning pawn ending.})1-0

```

In this example we saw that the rook can make multiple threats at the same time and take away squares from the bishop. This because the rook had many open ranks and files to work on, which made switching targets very easy to accomplish for the rook. If the rook is tied down and restricted, it becomes way less impressive, as can be clearly seen in the following example:

```
   [fen "1r6/2p1p1k1/p1B1P1p1/Pp3pPp/1P3P1P/2P5/5K2/8 w - - 0 1"]

   1.Ke3 Rd8 2.Bd7 {White doesn't let black get any activity whatsoever.} 2...Kf8 3.Kd4 Rb8 {There isn't much black can do.} (3...Rxd7+ 4.exd7 e5+ 5.fxe5 Ke7 6.e6 {is just a lost pawn ending.}) 4.Kc5 Ra8 5.Kd5! {Of course there are other ways to win, such as breaking with the c3 pawn to create a passer, but this nice use of zugzwang forces black to give up the c7 pawn without a fight.} 5...Ra7 6.Kc6 {and black's king has to move away from the e8 square due to zugzwang.} 6...Kg7 7.Bc8 Kf8 8.Bb7 Ke8 {Black's king can't get to d8 in time to defend c7.} 9.Kxc7 {and black will lose everything.}

```

Here black has an open file for the rook, but the rook is kind of dominated by the extremely influential bishop on c6, who can block the rook's path whenever black plays ...Rd8 by placing itself on d7, while at the same time keeping the black king imprisoned on the kingside. White wins by walking the king up the board to attack the weak pawn on c7, and there is little black can do about it besides watch in horror as the position starts to crumble.

Edit: I finally managed to think of an improved example of a bishop being stronger than a rook.

---
Tags: tactics, rooks, bishops, material-balance
---


# Question
Title: Alpha-Beta Pruning returns mate in two instead of obvious mate in one
I have an alpha-beta pruning chess AI that I have implemented using chessjs and chessboardjs. A friend of mine was playtesting it and came across the following position:

```
7r/ppp1k1rp/8/8/7K/4qb2/8/8 b - - 0 1

1... Qh6#
(1... Rhg8 2. Kh3 Qh6# (2... Rh8 Qh6))

```

In the position, black has a clear mate in 1 with Qh6. However, my alpha-beta algorithm, which is set to depth 4, first evaluates Rg8 (as it is the first move in the game.ugly\_moves() array from chessjs). With Rg8, black still has mate in two, with white playing Kh3 and black playing Qh6. Thus, alpha and beta will both equal the "checkmate score", beta\<=alpha satisfies, and the program returns, pruning the mate in one solution. Also, after playing Rg8, Kh3, black evaluates the board again, looking at Rh8 first, and yet again sees mate in two! (Either Kh2 or Kh4, then Qh6) and then the cycle continues (i.e. the AI plays Rg8, Rh8 until threefold repetition). Basically, in this position, I am always getting a draw instead of an obvious win.

Below is my alpha-beta implementation of this algorithm, in Javascript:

```
var minAI = function(depth, alpha, beta) {
  var options = game.ugly_moves();
  if (depth <= 0 || options.length === 0)
    return boardScore('b', game);

  var bestMin = 99999;
  for (var i = 0; i < options.length; i ++)
  {
    game.ugly_move(options[i]);
    if (game.in_threefold_repetition())
    {
      game.undo();
      continue;
    }
    bestMin = Math.min(bestMin, maxAI(depth - 1, alpha, beta));
    beta = Math.min(beta, bestMin);
    game.undo();
    if (beta <= alpha)
      break;
  }
  return bestMin;
}

var maxAI = function(depth, alpha, beta) {
  var options = game.ugly_moves();
  console.log("in maxAI");
  if (depth <= 0 || options.length === 0)
    return boardScore('b', game);
  var bestMax = -99999;
  for (var i = 0; i < options.length; i ++)
  {
    game.ugly_move(options[i]);
    if (game.in_threefold_repetition())
    {
      game.undo();
      continue;
    }
    bestMax = Math.max(bestMax, minAI(depth - 1, alpha, beta));
    alpha = Math.max(alpha, bestMax);
    game.undo();
    if (beta <= alpha)
      break;
  }
  return bestMax;
}

var bestAI = function() {
  var options = game.ugly_moves();
  if (!options.length) return;
  var bestScore = -99999;
  var moveIndex = -1;
  var alpha = -99999;
  var beta = 99999;
  for (i = 0; i < options.length; i++)
  {
    game.ugly_move(options[i]);
    var moveScore = minAI(maxDepth - 1, alpha, beta);
    if (moveScore > bestScore)
    {
      moveIndex = i;
      bestScore = moveScore;
      alpha = Math.max(alpha, bestScore);
    };
    game.undo();
    if (beta <= alpha)
    {
      console.log("we've been beta blocked");
      console.log(alpha);
      console.log(beta);
      break;
    }
  }
  game.ugly_move(options[moveIndex]);
  board.position(game.fen());
  if (game.in_checkmate())
    window.setTimeout(alert("checkmate!"), 250);
}

```

And here is how I give the board a score for a player (either 'w' for white, or 'b' for black):

```
var value = function(piece, player, i, j)
{
  if (piece === 'r') return (500 +
    (player === 'w' ? rookGridWhite[i][j] : rookGridBlack[i][j]));
  else if (piece === 'n') return (320 +
    (player === 'w' ? knightGridWhite[i][j] : knightGridBlack[i][j]));
  else if (piece === 'b') return (330 +
    (player === 'w' ? bishopGridWhite[i][j] : bishopGridBlack[i][j]));
  else if (piece === 'k') return (0 +
    (player === 'w' ? kingGridWhiteStart[i][j] : kingGridBlackStart[i][j]));
  else if (piece === 'q') return (900 +
    (player === 'w' ? queenGridWhite[i][j] : queenGridBlack[i][j]));
  else if (piece === 'p') return (100 +
    (player === 'w' ? pawnGridWhite[i][j] : pawnGridBlack[i][j]));
}

var boardScore = function(player, game) {
  if (scoreDict[game.fen() + ' [' + player + ']'])
    return scoreDict(game.fen() + ' [' + player + ']');
  if (game.turn() === player && game.in_checkmate())
    return -99999;
  else if (game.turn() !== player && game.in_checkmate())
    return 99999;
  var scoreWhite = 0;
  var scoreBlack = 0;
  for (var i = 0; i < 8; i ++)
  {
    for (var j = 0; j < 8; j ++)
    {
      var square = game.board()[i][j]
      if (square && square["color"] === 'w')
        scoreWhite += value(square["type"], player, i, j);
      else if (square && square["color"] !== 'w')
        scoreBlack += value(square["type"], player, i, j);
      if (scoreWhite <= 1100 || scoreBlack <= 1100)
      {
        kingGridWhiteStart = kingGridWhiteEnd;
        kingGridBlackStart = kingGridBlackEnd;
      }
    }
  }
  var posScoreWhite = scoreWhite - scoreBlack;
  scoreDict.push({
      key:   game.fen() + ' [w]',
      value: posScoreWhite
  });
  var posScoreBlack = scoreBlack - scoreWhite;
  scoreDict.push({
      key:   game.fen() + ' [b]',
      value: posScoreBlack
  });
  return (player === 'w' ? posScoreWhite : posScoreBlack);
}

```

The "grids" referred to above are 2D position-value tables as given in the link below: https://chessprogramming.wikispaces.com/Simplified+evaluation+function

I reversed the arrays given in that link for black's evaluations, and used the kingGridStart arrays until an endgame condition is reached, in which case I use the kingGridEnd arrays.

I am not sure how to go about fixing this. Did I understand why my alpha beta program is failing, or is there another reason I am not aware of?

# Answer
Add the depth information to the `99999`. Let's look at Stockfish:

> https://github.com/official-stockfish/Stockfish/blob/master/src/search.cpp

This block returns mate if **mated\_in** is true.

```
if (!moveCount)
        bestValue = excludedMove ? alpha
                   :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];

```

Let's check the **mated\_in** function:

> https://github.com/official-stockfish/Stockfish/blob/master/src/types.h

Please note Stockfish returns checkmate **plus** depth. That'd solve your problem.

```
inline Value mated_in(int ply) {
  return -VALUE_MATE + ply;
}

```
> 3 votes

# Answer
Well, there are two problems with your algorithm:

1. You don't treat draw (by whatever rule) in any way, meaning your AI will stubbornly run against a wall trying to keep the best possible position even if sacrificing a bit is likely to lead to a better outcome than draw.
2. You treat all moves leading to mate as equal. But as you found out, they aren't, which should be reflected in your code. So the evaluation should be a discriminated union:

* Number of Moves to mate, OR
    * heuristic evaluation of relative strength of players positions

You might be able to map it to a single value, with abs(value) \< MATE for the first, and BIG\_VALUE - abs(value) for the number of moves to mate otherwise.
> 3 votes

---
Tags: engines
---


title: Why wouldn't black take the rook here?

text:
# Question
Title: Why wouldn't black take the rook here?
This puzzle starts on move 19 of the below game. In order to get the puzzle correctly, it seems that you have to believe that black would not take the rook with 20.. gxf6. But I don't understand why this is – it's true that black will expose their king and breakup their pawn structure, but this seems like a small price to pay for taking the rook.

I ran it through the chess engine and it didn't seem to show any obvious traps that black would run into by taking the rook.

---

```
[FEN ""]
1. d4 d5 2. e4 dxe4 3. f3 { D00 Blackmar-Diemer Gambit: Gedult Gambit } Nc6 4. c3 Nf6 5. a3 e5 6. Be3 exd4 7. cxd4 exf3 8. Nxf3 Bg4 9. Bb5 a6 10. Bxc6+ bxc6 11. O-O Bd6 12. Qc2 Bxf3 13. Rxf3 Qd7 14. Nc3 O-O 15. Bg5 Be7 16. Raf1 Qxd4+ 17. Kh1 h6 18. Rf4 Qb6 19. Bxf6 Bxf6 20. Rxf6

```

# Answer
> 6 votes
After 20 ... gxf6 21 Ne4 black is in serious trouble. The threat is 22 Nxf6+ followed by 23 Qh7 mate, and in avoiding this she will have to make serious concessions. An example and not unreasonable line:

```
[Event ""]
[Site ""]
[Date "????.??.??"]
[Round ""]
[White ""]
[Black ""]
[Result "*"]
[FEN "r4rk1/2p2pp1/pqp2R1p/8/8/P1N5/1PQ3PP/5R1K b - - 0 1"]

1...gxf6 2.Ne4 Rfd8 3.Nxf6+ Kf8 4.Qh7 Ke7 5.Re1+ Kxf6 6.Qxh6+ Kf5 7.g4+
Kxg4 8.Qg7+ Kh4 9.Re4+ Kh5 10.Re5+ Kh4 11.Qg3# *

```

As a just below 1900 player I can't claim to be able to see all the variations, but over the board Ne4 is obvious enough to give me enough worries not to take the rook.To see all the glorious details stick it in an engine.

# Answer
> 2 votes
To complete Ian Bush's answer, I find this line pretty:

1...gxf6 2.Ne4 Rfd8 3.Nxf6+ Kf8 4.Qh7

\[4...Ke7 5.Re1+ +- Ian Bush\]

4...Qf2!? \[taking advantage of White's weak back rank\]

5.Ng8+! \[5.Qxh6+ Ke7 6.Qc1 Qd2 7.Qxc6 ought to be winning too, but it is not decisive yet\]

5...Ke6 \[5...Kf8 6.Nxh6+ Ke7 7.Qe5 Kf8 8.Re1 Qd4 9.Qe7+ Kg7 10.Nf5+; 5...Rxg8 6.Qe5+ and 6.Rxf2\]

6.Qxh6+ f6 \[The king cannot go to the f- nor the d-file because of Rxf2\] 7.Qh3+ Kf7 8.Qb3+ and 9.Rxf2 since the Qb3 covers d1 !

---
Tags: puzzles, rooks
---


title: Looking for a Horowitz game

text:
# Question
Title: Looking for a Horowitz game
I just remembered a puzzle from a Horowitz game in which he played white against an Italian (I believe) player whose name started with "M".

The black queen was defending f6, preventing Bxf6#. There was also a pawn about to promote on d7, and a rook stopping it on d8.

How can I find the game in which the position occurred? I can't recall Black player's name.

# Answer
Could it be Horowitz vs. NN (1939). (I realize "NN" doesn't start with an M, and may or may not be Italian, and the pawn isn't on d7... but memory can be a funny thing.)

This might be the position you're remembering:

```
rnb1qrk1/pppp1ppp/5B2/b2BP2Q/8/2P5/P4PPP/RN3RK1 b - - 2 13

```

I found this by putting in Horowitz playing as White in chessgames.com, then just sort of went through games in a pseudo-random order (start with "M", hit anything remotely Italian, guess at others) until I found a likely candidate.
> 2 votes

# Answer
If the game exists in a database, you can search for all games where Horowitz plays white. This search resulted in 151 games on chessgames.com. To further narrow the field, you can have it search by positions with a white pawn on d7 and a black rook on d8. This isn't a feature on any online database that I know of, but many databases do allow this. My database shows over 2100 games with these pieces, and is limited to games played after 1988. Neither of these searches provided me with this game, although I restricted it further by saying that white won. Maybe I should have checked players whose first name begins with 'M.'
> 1 votes

---
Tags: tactics, master-games, famous-games, download-games
---


# Question
Title: How much time on my clock do I have to lose before it is legal to stop notating?
When I play in tournaments, I do not know when it is legal to stop chess notation. Also, if my opponent stops notating, is it okay for me to stop notating as well?

# Answer
> 10 votes
According to the FIDE Laws of Chess:

> Article 8: The recording of the moves
>
> 8.4 If a player has less than five minutes left on **his** clock at some stage in a period and does not have additional time of 30 seconds or more added with each move, then for the remainder of the period **he** is not obliged to meet the requirements of Article 8.1.

Article 8.1 is the one that states that players need to keep record of the moves and what the players must and must not write to the scoresheet.

So:

> When I play in tournaments, I do not know when it is legal to stop chess notation.

You may stop notating when your clock shows less than five minutes and you get no increment or increment of less than 30 seconds. You have to start again at the start of the next period, that is, when more time is added to your clock (not the increment but for example at move 40).

> Also, if my opponent stops notating, is it okay for me to stop notating as well?

It makes no difference whether your opponent has to write the moves or not.

# Answer
> 3 votes
It's important to note that USCF rules differ from FIDE rules in this situation.

According to USCF rules 15B and 15C, both players may stop taking notation if either player has less than 5 minutes remaining. However, if a player is not taking notation, they lose the right to claim a draw by the 50 move rule or the 3 move rule, and lose the right to claim a win on time if it is a non-sudden-death time control (because they cannot prove how many moves they have played.)

According to rule 15F, the players must resume taking notation if they meet a time control which results in both players again having over 5 minutes left. In this case, they're also required to make "all efforts" to fill in all missing notation before they make another move. If both players need to update their scoresheets, the clock should be stopped while they do so, but if only one player needs to do so, his clock runs while he does this. If filling in the notation is impossible, they can construct a diagram of the position.

---
Tags: rules, etiquette
---


# Question
Title: What is the best way to solve chess puzzles?
Doing puzzles at lichess.org I stuck at raiting 1750 +- 50. I cant really go over 1800. So what are the first things one should check by solving puzzles? Are there some tricks how to solve puzzles?

# Answer
> 3 votes
I had hit a plateau like you. Probably spent about two years at the same tactical rating level until I watched a video on chess.com (it's a series, actually, by IM dpruess "Exercises to Become A Tactical Genius") that reshaped my thinking entirely.

What I used to do was analyze each of my pieces, one by one, and explore the possibilities of each piece. It was almost a guess-and-check type methodology. Often I'd get the puzzle correct, but I took so long at doing it that my tactical rating would only go up only one point. In a game, doing this, I'd surely lose on time before arriving at the correct combination.

The video I'm referring to got me thinking in terms of concepts first and only then explore those moves that would play to the concept that stuck out the most in the position.

My recommendation to you is to first familiarize yourself with a complete list of tactical concepts. Then, when you are looking at your next tactical position, see if you can spot the concept or concepts that might be featured in the position so that you can look for ways to exploit that feature. For instance, if you notice a piece is pinned, see if any moves jump out at you that will make good use of that fact. In my experience, this technique will save you a lot of time because you'll find yourself only analyzing a small subset of possible moves and the odds that the right moves are in that subset will be high.

As a word of caution, be prepared to see your tactical rating take a big dip while you get used to this new way of thinking, but I believe that once you get the hang of this way of thinking, you'll see your tactical rating shoot up. For instance, I found my rating plateau at 1900 for a couple of years, changed to this way of thinking and saw it drop to maybe 1800 and then shoot up to 2300. All the best to you. I hope this helps.

# Answer
> 2 votes
The correct way is to evaluate the positional strengths and weaknesses and find candidate moves based upon this evaluation. Another player complained that by knowing it's a tactical puzzle, you should just check the most outrageous move first. I complain that no one whispers in your ear that a tactic has appeared on your board.

# Answer
> 1 votes
I find it helpful to start by searching for forcing moves (where only one or two moves are legal, in case of a check, or nearly required, in the case of losing a queen), if for no other reason than it lowers the set of possibilities you consider before having to move on to a broader search.

Thinking through the process of creating a puzzle, a major challenge would be ensuring that there weren't better moves, or a different solution. Where the puzzle isn't a recreation of a historical position, the creator likely worked backwards from the final step and constructed the board around the path to that step. Because of this, many puzzles end up being a train of forced moves, where you're looking for fork/skewer/pin tactics to get to the final solution.

This could feel too much like studying for the quiz, rather than improving your actual chess skills, but I would argue that starting your analysis of the board in an actual game should also start by analyzing any available forcing moves.

---
Tags: tactics, puzzles
---