title: Features for evaluation a position

text:
# Question
Title: Features for evaluation a position
I am programming a (relatively basic) chess engine: while it is a lot of fun, it is also an interesting way to improve my chess skills! In order to evaluate a position, I need to extract features from the board. At the moment, I am using basic features such as the total value of the pieces, some features associated to piece mobility, open rank/files, whether the king is castled, some features related to the position of the pieces (eg. occupying the center is good), etc...

I was wondering whether there were resources describing more comprehensive list of features that would likely to be useful. This line of approaches has indeed been done a thousand of times (before the advent of neural-net / convolutional / AlphaZero types of methods) but I have not found many articles describing the features used.

# Answer
> 1 votes
The best way is read source code yourself. https://github.com/official-stockfish/Stockfish/blob/master/src/evaluate.cpp has the commented state-of-the-art rules defined in Stockfish.

---
Tags: programming, chess-ai
---


title: Why is Bf8 a blunder in this position?

text:
# Question
Title: Why is Bf8 a blunder in this position?
Here is an analysis of a game I played recently in Chess.com app. I won this match in move 19 as the opponent resigned.

Please see the image attached for the position. On move 16, after the White captured the pawn on d4 by his Knight, I moved my bishop back to f8 from e7. This move opened the rook on e file and caused a double attack on the e4 pawn.

But the chess.com analysis marked this as a blunder, can anyone explain why?

Thanks in advance for any explanation ( my chess.com rating is around 1200 so I'm a new player ).

Thanks for the people who explained about the pawn capture move, but my doubt is : usually this kind of ignorances are called "Mistake", "Inaccuracy" or "Missed win" in chess.com right? Why the term "Blunder"?

# Answer
Bf8, while a nice positional move, an excellent idea for a 1200 rated player, is a mistake as Nxe4 wins an important central pawn for no compensation. The Queen can't recapture due to the coming skewer down the long diagonal. See the lines below.

Remember tactics always trump strategy!

```
[White ""]
[Black ""]
[FEN "1k1rr3/1bpqbp2/ppnp1n1p/6p1/3NP1P1/P3Q1BP/1PP1NP2/2KR1B1R b - - 0 1"]

1...Nxe4 2.Nxc6+
    ( 2.Qxe4 Nxd4 3.Qxd4 Bxh1 )
2...Qxc6 *

```
> 6 votes

---
Tags: analysis, stockfish, blunder, chess.com
---


title: What opening variation begins with c4?

text:
# Question
Title: What opening variation begins with c4?
Black’s best response to White’s c4 opening move; what is the name of this opening?

# Answer
This is called the English Opening. The objective of the opening is to apply pressure on the center d5 square without committing the queen pawn or the king pawn. The standard response is 1..., e5 (Reversed Sicilian), but there are many other options, 1..., c5 for example (Symmetrical) or 1..., e6, a more manuevering type of game. This opening is known for its transpositional possibilities. For example it often ends up as some form of Queen's Pawn Opening. It is favored by many players because of this non-committal nature.
> 2 votes

---
Tags: opening
---


title: Why is the engine suggesting this move?

text:
# Question
Title: Why is the engine suggesting this move?
```
[FEN "r1bqk1nr/p1ppbppp/1p6/n2P4/8/2N5/PPP1QPPP/R1B1KBNR w KQkq - 3 7"]

1. g4

```

With White to move, the Lichess engine suggests g4 in this position. Can someone explain why it's a good move?

# Answer
> 22 votes
Black would like to continue their development with Nf6 and castling short. g4 discourages Nf6; after g5, the knight is forced back. It also prepares Bg2, which protects d5 without giving up the pin on the e-file. The weakening of the kingside apparently isn't too much of a problem; Black isn't developed enough to take advantage of this, and White can always castle queenside.

---
Tags: analysis, strategy
---


# Question
Title: FIDE Online Arena: what specifically determines bullet, blitz, rapid, and unmonitored time controls?
I've been trying out the FIDE Online Arena; while I've found a lot of marketing, I find very little useful documentation (possibly because the software is new).

FIDE Online Arena has four different Elos: bullet, blitz, rapid, and unmonitored.

Q: What specifically determines bullet, blitz, rapid, and unmonitored time controls?

# Answer
According to FIDE:

Blitz: \<= 10 minutes

Rapid: \> 10 minutes and \<= 60 minutes

Source: http://www.fide.com/component/handbook/?id=171&view=article (See appendices)

---

According to Wikipedia and **many** online chess platforms:

Bullet: \< 3 minutes

Blitz: \>= 3 minutes and \< 10 minutes

Rapid: \> 10 minutes and \<= 60 minutes

Source: https://en.wikipedia.org/wiki/Fast\_chess
> 5 votes

# Answer
Yes, exactly. Blitz: 3-5 minutes per side, usually no increment. Bullet: 1 or 2 minutes per side. Rapid: 15 to 60 minutes per player. sometimes with a small time increment per move for example 10 seconds.

For me personally, i like it so far because as far as i know, FIDE online arena is one of the Premium Chess members which i suppose all of National Federations are also members of Premium Chess. And its very interesting to play with people from world federations. The interface indeed can be improved a lot, but i do like their design and website.
> 3 votes

# Answer
I think all the above said is true - but i think most online chess platforms differ a little from the fide definition:

FIDE takes

```
Basetime + 60 * increment

```

for their calculation and then says

* Bullet \< 3 minutes
* Blitz \<= 10 minutes
* Rapid \<= 60 minutes

While most other platforms take

```
Basetime + 40 * increment

```

as a base for their calculation - so the very weird timecontrol 0 minutes + 4 seconds per move is usually considered Bullet
> 2 votes

# Answer
For the FIDE Online Arena, only *specific* time controls can be rated. For example, you can play a rated 5 minute or 10 minute blitz game, but if you play a 7 minute game it will always be unrated.

According to the FIDE Online Arena Rating Regulations, the ratable time controls are as follows:

> 2.3 Rated games use the following predetermined time controls:
> 2.3.1 For rapid chess: 15m, 25m, 45m, 10m + 10s, 15m + 10s, 25m + 10s, 45m + 10s
> 2.3.2 For blitz chess: 3m, 5m, 10m, 3m + 2s, 3m + 3s, 5m + 3s
> 2.3.3 For bullet chess: 1m, 2m, 1m + 1s, 1m + 2s
> 1 votes

---
Tags: fide, online-chess, time-control
---


title: Finding a piece to promote a pawn

text:
# Question
Title: Finding a piece to promote a pawn
There is only one queen of each color is a chess set. When a pawn gets promoted, say to a queen, where does that queen come from?

# Answer
Most over the board sets come with 4 queens total (2 of each color) for exactly this situation. It's quite likely that at some point in your games, you'll need to have 2 queens on the board simultaneously, so they give you the main queen and a spare.

If you really need more than 4 queens, you can always "steal" another piece from your neighbors' game so that you have enough pieces to continue playing. Just make sure you give it back when one gets captured or they'll be mad with you!

Of course, it's possible to have 9 queens simultaneously, but it would be unnecessary for any chess set to give you this much redundancy on the off chance you decide to troll your opponents and promote every piece to a queen. Same thing with underpromoting so that you have 10 knights, 10 bishops, or 10 rooks...
> 1 votes

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


title: Square Free Position

text:
# Question
Title: Square Free Position
```
 [FEN ""]

```

For the purposes of this question, a “square” is a set of four occupied cells on the chessboard whose centres form a geometric square. The cell may have any orientation. For example: a1,a2,b2,b1 or a2,b3,c2,b1 or a2,b4,d3,c1.

In the starting position, there are 24 squares that are formed by four Black and/or White pieces. Two squares are tilted. If regular moves/captures are played for Black and White, what could be the maximum number of pieces that can remain on the board without four them forming a square?

# Answer
## TL;DR: a solution!

```
[FEN "rnbq1bn1/p2pp1p1/1p2r1Nk/2p4p/6PN/1BPP1p1P/PP2PP2/R1BQK2R w - - 0 1"]

```

32 pieces, no squares.

According to OEIS sequence A240443 and this particular pair of examples, 34 is the maximum possible number of square-free points on an 8x8 grid. As long as each file has at least two points in ranks 2-6, this is likely to give us a solution, if we just drop a couple of the points. (I picked two from the more crowded files.)

This is not intended to be optimal in number of moves - it just shows that a capture-free solution is possible, and is a starting-point for the search for the shortest (non-unique) proof game (which we now know lies somewhere between 4.5 & 7.5 moves).

The rest of this post gives more details.

## Generalization to abstract math problem

Overall, I make it 336 possible “squares” on the chessboard, of which 140 are non-tilted and 196 tilted. Since about 60% are tilted, avoiding the tilted squares in a general position is the harder challenge, although there were only 2 tilted squares to avoid in the game array.

Following an exploration into positions where ranks 3-6 were empty, I think the best general approach may be to forget about the chess for a while. We've got 64 nodes, and 336 "quartets", each of 4 nodes. What's the smallest subset of 64 which contains a member of each quartet? There is no a priori reason why that smallest subset should be greater than 32. (I.e. we might be able to have more than 32 pieces on a square-free board!) Anyway, after that smallest subset is determined, we can see how we can arrange chess pieces to avoid those squares on the board.

Having got a solution, the next thing might be to determine all maximal arrangements of 32-34 square-free points which allow for 2 pawns/file. (It’s the 34-pointers which are most interesting, although it’s possible that some position with 32 or 33 point might not be extensible to 34, so would be missed in any trawl of 34-pointers.) Can then look at the smallest number of moves to reach positions which have 32 pieces. In such open capture-free positions, it seems very unlikely that a unique proof game exists.

If anyone does get a list of these maximal 32-34 point diagrams, I would be grateful if they can be posted in GitHub. There is some python code in OEIS, I saw.

## Bounds for shortest (non-unique) proof games

An earlier reconnaissance to look at homebase positions (i.e. where all surviving units are on their apparent starting squares) proved that a maximum of 23 units can remain on the board. A valid implication for the general problem is that any (non-unique or unique) proof game to a square-free position must have at least 4.5 moves (i.e. White moves at least 5 times). This bound is unlikely to be attainable.

Elsewhere in this thread, there is a solution in 7.5 moves. Any faster solution must therefore have at least 9 units on ranks 1 & 2, and at least 9 units on ranks 7 & 8. This constrains somewhat the search for interesting 32-34-pointers.
> 10 votes

# Answer
Playing around with Laska's board position, here is a 10 move sequence that gets there (with some pieces moved around):

```
[fen "rnbq1bn1/p2pp1p1/1p2k1Br/2p4p/6PP/1NPP1p1N/PP2PP2/R1BQK2R b KQ - 1 10"]
1. d3 c5 2. c3 h5 3. g4 Rh6 4. h4 f5 5. Nh3 Kf7 6. Bg2 f4 7. Be4 Ke6 8. Bg6 f3 9. Nd2 b6 10. Nb3

```
> 5 votes

# Answer
Here's an 8.5 move sequence that leaves no squares:

```
[fen "r3kb1r/pp1nq1pp/4b2n/2pppp2/1P1P1P2/N6P/P1P1P1PR/RNBQKB2 b Qkq - 0 1"]
1. d4 d5 2. b4 c5 3. f4 e5 4. h3 f5 5. Nf3 Be6 6. Nfd2 Nd7 7. Nc4 Nh6 8. Nca3 Qe7 9. Rh2

```

Edit: 7.5 moves (see comments)

```
[fen "rnbqkb2/p1p1p1pr/Q6p/1p1p1p2/2PPnP2/4B2N/PP1NP1PP/R3KB1R b KQq - 3 8"]
1. c4 b5 2. d4 d5 3. f4 f5 4. Qa4 Nf6 5. Qa6 Ne4 6. Be3 h6 7. Nd2 Rh7 8. Nh3

```
> 4 votes

---
Tags: problems, puzzles, mathematics
---


# Question
Title: EXTENDED New Year's Math Riddle: 5-fold repetition & 75-move rules
This puzzle extends Rewan Demontay's New Year Math Riddle.

Rewan asked (essentially): if the players co-operate, what's the largest number of times a given diagram can occur in a game before reaching the point when someone can claim a draw? In order to group everything together, I'll re-state that question as Q1 here:

> Q1: Under the 3-fold repetition & 50-move rules, how many times can a diagram occur? Call a diagram which achieves this 3-critical.

> Q2: Under the 5-fold repetition & 75-move rules, how many times can a diagram occur? Call a diagram which achieves this 5-critical.

Now let's make some actual chess games:

> Q3: Find a 3-critical diagram that is a unique shortest proof game to its first occurrence.

> Q4: Find a 5-critical diagram that is a unique shortest proof game to its first occurrence.

# Answer
## Answers to all 4 questions

> Q1: Under the 3-fold repetition & 50-move rules, how many times can a diagram occur?

A1: Even if it were mandatory, the 50-move rule has no impact: the answer is still 22 as per Rewan's post:

```
   2 (occurrences without triggering the draw)
 x 2 (White or Black to move)
 x 5 (number of castling rights intact: 4->3->2->1->0)
= 20
 + 1 (en passant)
 + 1 (the final 3rd occurrence)
= 22 times

```

There are 21 transitions between the 22 occurrences, each taking at least 2.0 moves which gives 42.0 moves. Also we must flip sometimes between White & Black having the move, which takes an extra 0.5 of a move each time to triangulate. If White were to move in the first, the player to move in each of the 22 critical positions is:

```
W-WWBB-BBWW-WWBB-BBWW-WWBB-B

```

Five 0.5 flips give a total of 42.0 + 5 * 0.5 = 44.5 moves.

Note that we require a diagram where parity can be switched by a free bishop or queen, as knights can't triangulate, and kings & rooks are tied up with castling rights. Rewan's diagram is sufficient for this, in order to achieve the 44.5, and in fact we still have a little slack and could waste another 5.0 moves. Because of e.p., the move prior to the first occurrence of the diagram was a pawn move, which zeroed the 50-move clock. For definiteness, let's say that the maximum is 49.5, to avoid draw by repetition *and* 50-move rule on the same move.

> Q2: Under the 5-fold repetition & 50-move rules, how many times can a diagram occur?

A2: One might think that the answer is 42:

```
   4 (occurrences without triggering the draw)
 x 2 (White or Black to move)
 x 5 (number of castling rights intact: 4-3-2-1-0)
= 40
 + 1 (en passant)
 + 1 (the final 5th occurrence)
= 42 times

```

But in fact the diagram can only occur 37 times now, not 42.

There are 41 transitions between the 42 critical positions. Each takes at least 2.0 moves, which takes 82.0 moves, together again with the 2.5 moves for parity switching so that the player to move in each of the 42 critical positions is:

```
W-WWWWBBBB-BBBBWWWW-WWWWBBBB-BBBBWWWW-WWWWBBBB-B

```

84.5 moves would be needed, but the game will end at 75.0. So how many occurrences of the diagram can we get before we bring the game to a close by 5-fold repetition, *before* the 75-move rule ends us? If our budget is 74.5 (or even 75.0) moves, so we must eliminate 5 recurrences.

It takes us 74.0 moves to reach the diagram for the 37th time. By skipping the en passant threat at the beginning, we can reach the position more quickly.

```
BBBB-BBBBWWWW-WWWWBBBB-BBBBWWWW-WWWWBBBB-B

```

> Q3: Find a 3-critical diagram that is a unique shortest proof game to its first occurrence.

A3: PG in 3.5. The last move to reach this position for the first time is a pawn move, as we then launch into the full 44.5 move sequence.

```
[FEN "r1bqkbnr/pppp1ppp/n7/8/4pP2/8/1PPPP1PP/RNBQKBNR w KQkq - 0 1"]

```

> Q4: Find a 5-critical diagram that is a unique shortest proof game to its first occurrence.

A4: Proof game in 2.5 moves to a diagram which can occur 37 times.

```
[FEN "rnbqkbnr/1ppp1ppp/B3p3/p7/8/4P3/PPPPNPPP/RNBQK2R w KQkq - 0 1"]

```

This will take us 84.5 - 10.5 = 74.0 moves, which is *perfect* because White's 3rd move to reach the diagram for the 3rd time is not a pawn move or capture. So the game does not end prematurely by conflated draws by 5-fold repetition & 75-move rule.
> 3 votes

---
Tags: mathematics, threefold-repetition, 50-move-rule, 75-move-rule, fivefold-repetition
---


# Question
Title: Is there a good strategy to achieve a draw?
# Background

Sometimes I face players who are much stronger than me and my first thought is, 'I just need a draw in this match' so I play "carefully"

# My Current Strategies

## Offer a draw

It almost always never works! Plus this also takes away the beauty in chess, fun.

## Try closed positions

Sometimes I just aim for something like it. This strategy sometimes works until the moment I see a crazy Bishop sac somewhere to open up the position!

```
[FEN "*"]

1. e4 e5 2. d4 c5 3. d5 d6 4. c4 b5 5. a4 b4 6. b3 a5 7. f3 h6 8. h4 f5 9. h5 g5 10. g3 f4 11. g4 Nf6 12. Bxf4

```

## Exchange Pieces

This strategy has another problem, the more pieces are exchanged the more the end game nears bringing about *end game* Stronger players will definitely be better in the end game than I am, so this strategy is actually a suicide.

# Conclusion

Drawing in chess is hard. Maybe someone has an idea of a way to easily draw.

# Answer
The best strategy to try and draw against a stronger player is also the best strategy for all your games:

* Play the position not the opponent
* Try and aim for positions which you know and are comfortable with
* Always try and find the objectively best move
* Particularly important for weaker players - play prophylactically. When it is your turn always first ask yourself the question "What is my opponent trying to do?" and then "How can I stop their plans?"

Although all four are important the last one is the most important. If you counter all your opponent's plans and don't make any mistakes then you are going to get at least a draw.

Problems arise when you aren't good enough to work out your opponent's plans and when you don't recognise a mistake but if you are always asking then you are already one very big step ahead of the player who is not playing prophylactically.
> 9 votes

# Answer
Play normally. Forget about your opponent's rating.

Both closing the position and trading off pieces will make it easier for a strong opponent, especially if you are doing it at a concession. They have better positional understanding and technique. It might make it seem like you were close to draw because the game lasted more moves or because it came down to pawn ending, but at the same time your opponent might not have had to work very hard.

Also, unless there is a specific reason that you only need a draw, again, play normally, wouldn't it be great to beat a stronger opponent?
> 6 votes

# Answer
If you want a draw, you play for a win. If you want a loss, play for a draw.

If a weaker player offers me a draw, I'll ignore it - even see it as a weakness of confidence. But if we get to a complicated position where I think it's too risky, I might offer them a draw. Which they should decline.

Don't play for a draw unless the position is actually drawn, you gain nothing from it. You should also not accept a draw if you're in a better position even against a strong opponent.

In fact I will play on in a nearly drawn position against some weaker players, because they do mess up or overlook certain ideas that lead them to a worse position.

The only acceptable exception is a tournament situation where a draw is as good as a win. Then as the stronger player you may offer an early draw, but not as the weaker player.

If you play for a draw and take little risk, you're just giving the stronger player free reign to twiddle about until they find a good idea, all the while you're not generating adequate counterplay or threats. If you make the game only 2 results for them where they will either draw or win, you're making their play much simpler.

It's the equivalent of being in a boxing match and your plan being "just try to dodge the punches and move about the ring and protect your face at all times". You'll just get jabbed and jabbed until you make one mistake and you're KOed. Instead actually throw some punches so you have some shot.
> 2 votes

# Answer
I have no idea why you think the 'crazy bishop sac' is a single bit good at all! You lose material for no positional gain whatsoever! Stockfish 10+ agrees. If this kind of pointless sacrifice is what you are going to do after getting a 'closed' position, you are going to achieve a loss, not a draw. As others already said, the best way to achieve a draw against a stronger player is to play correctly and towards positions you are more comfortable with, rather than trying to aim for closed positions for no good reason (especially given the example you showed here in which you did not play well at all).
> 1 votes

---
Tags: strategy, draw
---


title: Chessboard Materials

text:
# Question
Title: Chessboard Materials
```
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"]

```

Starting a game with a total of 78 point-value, how many legal moves are required to produce the maximum total point-value on a chessboard?

# Answer
Of course, promoting all the pawns to queens must be done. Creating sixteen passed pawns requires sacking eight pieces, four per side. The sacked pieces should be the knights and bishops to preserve the higher value pieces. From there, it's merely an "Onward, ho!" to a total point value of 182, which comes from the nines queens and two rooks on each side.

Here is one example game in 51 moves, or 102 plies. Since getting 18 queens alone takes 48 moves, or 96 plies, this is almost optimal, I feel.

```
[FEN ""]
[startply "102"]

 1. c4 f5 2. c5 f4 3. c6 f3 4. b4 g5 5. b5 g4 6. h4 a5 7. Nh3 Na6 8. bxa6 gxh3 9. g4 b5 10. Bg2 Bb7 11. cxb7 fxg2 12. h5 a4 13. h6 a3 14. Bb2 Bg7 15. hxg7 axb2 16. a4 h5 17. a5 h4 18. e4 d5 19. e5 d4 20. Nc3 Nf6 21. exf6 dxc3 22. d4 e5 23. d5 e4 24. f4 c2 25. f5 e3 26. f7+ Kd7 27. f6 e2 28. d6 c5 29. Kd2 c4 30. f8=Q c3+ 31. Kd3 e1=Q 32. g8=Q b1=Q 33. a7 Rc8 34. Rf1 Qde7 35. f7 g1=Q 36. Qh7 Ke6 37. d7 b4 38. a6 b3 39. a8=Q h2 40. a7 Qa2 41. b8=Q b2 42. Qab7 c1=Q 43. a8=Q Qf4 44. g5 c2 45. g6 b1=Q 46. g7 h1=Q 47. d8=Q Qhg2 48. g8=Q h3 49. Qfg7 h2 50. Qge8 h1=Q 51. f8=Q c1=Q+

```
> 3 votes

---
Tags: problems, point-value
---


# Question
Title: On a glass board, which squares are "white"?
I have a chessboard made of alternating frosted and clear glass pieces. I'm never sure how to orient the board. Which is the official "light color" to put in the lower right corner?

# Answer
At the lower right corner, the square's color should be White. I have seen some glass chess boards and most of the times the frosted pieces/squares represent the Black side, and the clear pieces/squares the White side.
> 5 votes

# Answer
A few points for consideration here for Standard Chess:

1. Lower Right Corner is White
2. White King is placed on black square, 4th from right. This square becomes e1.
3. Point 2 leads to Black King being placed on white square, 4th from left. This is now e8.

Now when you place the board like this, it doesn't really matter whether you treat frosted or clear glass as white.

Just for records, I have seen most people treating frosted glass as WHITE. But there are people who play as white with clear glass pieces.

It should not matter as long as you orient the board right.
> 4 votes

# Answer
Naturally, clear is white and frosted is black. But it doesn't quite matter as these sets are meant to be aesthetic rather than functional.

Edit: it appears I'm in the minority. I think of it more as clear and shaded. If the tint on the pieces were green, wouldn't the lighter (clearer) ones be considered white?

In some chess books, the white pieces on paper are clear while the black ones are shaded.
> 2 votes

# Answer
I've always done it in correlation with the squares on a glass chess board. The clear squares on the chess board look black where as the frosted ones look white, so it makes sense for me to use the clear pieces as black and the frosted pieces as white.
> 1 votes

---
Tags: beginner, chessboards
---


# Question
Title: Why is exchanging these knights the best move for white?
Why is exchanging these knights the best move for white? I'm trying to understand how to get better with strategy and tactics.

# Answer
> 13 votes
Despite the difference in evaluation, e4 is not really a mistake. White is a rook ahead and will win this game anyway, provided that they don't blunder. Perhaps Nxc4 leads to a victory a few moves faster, almost within the engine's search horizon; that's probably why the engine prefers it over e4.

However, even humans should prefer Nxc4. **If you're this far ahead, you should exchange material; every exchange means less chance of threats from your opponent.** A two-to-one advantage is much more decisive than an eight-to-seven. Black's knight is also more active than White's, that's another reason to exchange it. (That the engine indicates that *Black* should exchange knights after e4 is surprising, but it only underlines how bad Black's position actually is.)

The advice about exchanging when you're ahead is of course not a rule set in stone. You should always keep in mind the (potential) activity of the exchanged pieces. And if you're only a pawn ahead, that doesn't need to be decisive enough for the win. Rook endgames and endgames with opposite bishops are notoriously drawish, and there are more examples out there, but you don't have to worry about them for now.

# Answer
> 8 votes
Strategy aside, Nxc4 also simply wins another (center!) pawn, while developing the light squared bishop to a nice square (assisting to continue to attack Black's kingside).

On top of limiting Black's options for counterplay, as the other two answers correctly state.

# Answer
> 8 votes
Look at the engine line! After your move, black voluntarily exchanges knights and plays ...f6, trapping your dark squared bishop. Now, white is still completely winning since you're up so much material and I don't see a direct way for black to try and win the bishop, but you're allowing black unnecessary ideas.

Instead, the suggested best line to play f4 after an exchange of knights forces Nf6 as there's no other way to defend the knight for black. Now you can trade bishop for knight, trading down even more material and getting you closer to a completely winning endgame. (You could also go Bxc4 first like the engine suggests, then trade the h8 bishop for knight later.)

This answer is not comprehensive, the other answers also raise excellent valid points, of course.

# Answer
> 4 votes
e4 is still winning but not necessary because you are giving away the f4 square to Black's knight, which gives them some counterplay. There is no good reason to give f4 to your opponent.

---
Tags: analysis, learning
---


# Question
Title: What was the best move for white? Could white have won?
Could white have won this game? What was the best move in this position for white? Or could Black have won?

# Answer
> What was the best move in this position for white?

QxQ is the best move. White is a piece up so the best plan is to try and exchange pieces. Once only the pawns and white's last piece are left the win becomes very easy. QxQ is a great way to start implementing that plan.

> Could white have won this game?

White has more than enough material to deliver checkmate, so, yes. Obviously there is no immediate win. There are no real threats and no possibility of checkmate for a while but in the long run with reasonable play white should win.

> could Black have won?

Again black has more than enough material to deliver checkmate, so, yes, black *could* win. However this would require white to blunder because white is material up. Anybody who has played much chess knows that blunders happen all the time. So at lower levels definitely worth while for black to play on.

Here, for instance, if white were dumb enough to play the moves Bc4, Ne2 and Kf1 then black could play Qd1 checkmate, so, yes, a black win is still possible although extremely unlikely.
> 2 votes

# Answer
Yes, white can win this game. All you have to do is exchanging the pieces. Think like that;

For example, you have 1000 soldier and the opponent have 950 soldiers. You do not know that you are going to win this war or not. Think about 51 to 1. You definitely win the war. When you are piece up, the main strategy is exchanging the pieces as much as you can. If you are a piece down, my advice is to exchange the pawns. For sum up

> Exchange pawns when you are a piece down
> Exchange pieces when you are a piece up
> 0 votes

---
Tags: analysis, strategy, checkmate, tactics
---


# Question
Title: A question about draw detection in chess engines
Let us look at this position.

```
[FEN "4k3/8/8/p1p1p1p1/P1P1P1P1/8/8/4K3 w - - 0 1"]

```

This is obviously a draw. Analyzing this with the Stockfish engine says that it is a balanced position. However, Stockfish does not recognize that it is a draw.

Slightly rearranging the pawns, we receive a similar position that is an obvious draw.

```
[FEN "4k3/3p4/p1pPp3/P1P1P1p1/6P1/8/8/4K3 w - - 0 1"]

```

Here, Stockfish says that white has an advantage of +0.7.

Where does this miscalculation come from? I understand that draws in these positions cannot be detected from tablebases, as there are still too many pieces on the board. It seems that these special positions are called Pawn Rams or Blockages.

The chess programming article about Blockage Detection provides code for detecting blockages, but I do not understand how it works.

What are the underlying factors that make draw detection so hard from a computational point of view?

# Answer
> 3 votes
I actually did the experiment and will answer now. Three main factors go into the evaluation (as king safety doesn't play the slightest role): material, space, and movability.

The effect of space is rather high at +1.4.

```
[FEN "4k3/p1p1p1p1/P1P1P1P1/8/8/8/8/4K3 w - - 0 1"]

```

Any useless doubled pawn is about +0.7, giving +4.2.

```
[FEN "4k3/p1p1p1p1/P1P1P1P1/P1P1P1P1/8/8/8/4K3 w - - 0 1"]

```

Don't underestimate agility, we're already at +5.9.

```
[FEN "4k3/p1p1p1p1/P1P1P1P1/8/8/8/P1P1P1P1/4K3 w - - 0 1"]

```

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

---
Tags: engines, programming, draw, 50-move-rule, dead-position
---


# Question
Title: In the books Wojo's Weapons, why was Wojo occasionally known to say "I'm too lazy!" when asked why he didn't play 1. d4 instead of 1. Nf3?
In *Wojo's Weapons: Winning With White (Volume 1)* by Jonathan Hilton and Dean Ippolito, it is written:

> Wojo's move order to reach any opening position almost always started with 1. Nf3 and then either c2-c4 or d2-d4. When asked why he didn't play 1. d4 as his first move instead, he was occasionally known to say, "I'm too lazy!"

I don't really understand why he says that.

If I am not wrong, if you want to play c4, d4, Nf3, g3, (not against everything, but against most defenses), then the difference between starting with 1. Nf3 and starting with 1. d4, is that starting with 1. Nf3 avoids all of these openings:

* The Budapest Gambit
* The Albin Countergambit
* The Benko Gambit
* The main lines of the Grunfeld (I think)
* The Benoni
* The Nimzovich Variation (Exaggerated Fianchetto) of the QID

At the price of allowing Black to play the English.

Technically starting with 1. d4 also allows White to play these three variations:

* The Samisch against the KID
* The 4-Pawns Attack against the KID
* The Exchange Variation against the QGD

But since White is going to also play Nf3 anyway (on move 3), he is not going to play any of those variations.

So if we intend to play c4, Nf3, d4, g3, I would believe that choosing to start with 1. Nf3 is the most intelligent choice since it avoids so much openings at the (small) price of allowing Black to play the English.

But this isn't laziness. It's just cleverness, it's the wise choice to make. So I still don't understand Wojo's quote.

So what did I miss? Does starting with 1. d4 avoids other openings that 1. Nf3 allows? Are there other advantages of starting with 1. d4 ?

# Answer
> If I am not wrong, if you want to play c4, d4, Nf3, g3, (not against everything, but against most defenses), then the difference between starting with 1. Nf3 and starting with 1. d4, is that starting with 1. Nf3 avoids all of these openings:

That is exactly the reason why I always open with `1.Nf3` :)

You should have seen the look on some faces after they realize they can't play their gambit openings and must agree to play "dull" game. I really don't care, since I will always be rock-solid and safe, and since I am White I can usually open the center if I want "trouble".

> At the price of allowing Black to play the English.

Yeah... But it's not so bad, since English is so rich in ideas that it rarely ends in a draw if at least one side fights really hard for a win. This can be useful against lower rated opponents because they can't spring some dull opening line and draw by "suffering" all game. Theory is less important, than knowledge of plans which is also great, since lower rated opponent can't draw because he just bashed out 20+ moves of forced line.

As for equally rated opponents, this is great opening as it allows you to overpower the opponent with your intelligence and creativity, which should suit your style, based on your earlier posts.

> Technically starting with 1. d4 also allows White to play these three variations: But since White is going to also play Nf3 anyway (on move 3), he is not going to play any of those variations.

Which is the reason you will not see `1.Nf3` at the top so often -\> the flaw of this move is that it avoids the best lines for White in many openings. Black can reach full equality rather easy ( like in QGD Exchange line... ), but still, positions are enough unbalanced for you to win. With `1.Nf3` you sacrifice objectively the most dangerous lines for Black, for safety and flexibility. It all depends of person's style. I like solidity, and have no problem with playing equal positions. Just because the position is equal desn't mean it is a dead draw. If you are creative, you can sharpen it and play for a win...

> So if we intend to play c4, Nf3, d4, g3, I would believe that choosing to start with 1. Nf3 is the most intelligent choice since it avoids so much openings at the (small) price of allowing Black to play the English.

Indeed. Just remember that this move order offers you no advantage. You will always play equal positions, but you will be rock-solid and flexible. Consider the option of playing King's Indian Attack, instead of playing `d4` for example... This is a good option for White too, you do not need to limit yourself with `d4+c4` pawn formation.

> So what did I miss? Does starting with 1. d4 avoids other openings that 1. Nf3 allows? Are there other advantages of starting with 1. d4 ?

`1.Nf3` cuts down on the amount of theory you need to learn, but you will never play the most critical lines for Black. With `1.d4` this is not the case, but you will have to learn much more, since you can't bypass some heavily theoretical openings... It's up to you to make the choice.
> 4 votes

# Answer
Alex (may he RIP) told me: "Nf3 I can choose whether or not to play d4 and when...if at all. With Nf3 I blackmail the opponent. With white I play for solid advantage and black has to play precisely not be worse. With black it is worth it to play more "dynamically" and take a risk.
> 0 votes

---
Tags: opening, theory, positional-play, books, 1.d4
---


# Question
Title: How can I get multiple computer recommended lines in python-chess module?
In python-chess you can communicate with the engine on a given position. However the method presented in https://python-chess.readthedocs.io/en/latest/uci.html using the engine.go() function with only a time parameter returns just one continuation and that continuations evaluation.

I know in most chess programs you can see the top few ranked positions and their evaluations. How can I do the same in python chess? None of the parameters in engine.go seemed to let me do that.

# Answer
You can do this by sending out MultiPV, something like:

```
engine = chess.uci.popen_engine(...)
engine.setoption({ "MultiPV" : multiPV})

```

The module will generate multiple lines for you, as an array.
> 4 votes

# Answer
As the version of python-chess I'm running doesn't support chess.uci, here's what worked for me.

```
engine = chess.engine.SimpleEngine.popen_uci("/path/to/engine.exe")
board = chess.Board()
info = engine.analyse(board, chess.engine.Limit(time=10),multipv=20))

```

info is a list of InfoDict objects, each with the keys "pv" and "score", the list of moves in the line, and the evaluation respectively.
> 2 votes

---
Tags: software, programming, python
---


# Question
Title: Is there a name for this common online trap in the Modern Defence?
In online blitz and bullet, I often encounter Black trying to get an edge on the clock by premoving 1 .. g6 and 2 .. Bg7. A devious way to deal with this as White is to play 2. Bh6??, winning at least a rook if Black commits to their premoves.

```
[FEN ""]
[StartPly "3"]

1. d4 g6 2. Bh6 Bg7 3. Bxg7

```

Does this trick/trap/strategy of White have a common name?

# Answer
In online chess, this is commonly referred to as the 'Lefong' inspired by FM Lefong Hua of Canada. Here is a clip with Magnus referencing it.
> 6 votes

---
Tags: opening-traps, online-blitz
---


title: Is Choker balanced?

text:
# Question
Title: Is Choker balanced?
Choker (chess + poker) was released recently as a mobile app. It is a game where players have a round of poker to bet on cards they draw. They then use these cards to play chess and win the bets. It's 1 on 1, like regular chess.

1. My concern is that choker is not quite balanced in that I think it happens too frequently that one of the players has a really strong hand in that the other ends up being down a piece.
2. Another reason I think this is especially due to the fact that you cannot see your opponent's pieces until they place all of them. (However, this does not seem to be the case in the most recent version of the app.)
3. Also, there's that you can't quite have 2 pieces of the same "suit" (there are pre-chess-promotion and demotion rules) or even place the pieces except pawns anywhere on our side besides the 1st 2 rows.

Question: Is this a balanced game?

Sub-questions: What are the probabilities of the hands in choker? How far apart are the 2 player's hands on average? Do the promotion/demotion rules make choker less balanced?

# Answer
> 6 votes
> My concern is that this is very unfair to one of the players as often even strong hands are not strong enough and end up being down a piece.

But in regular poker, the hand would simply be over at this point. If you're looking for a fair chess game, just play chess!

I included the promotion/demotion/palace/empress rules and simulated a million hands, and came up with the following material imbalances:

```
0   : 141731
2   : 268811
4   : 223876
6   : 154819
8   : 94144
10  : 54601
More: 62018

```

This is slightly more equal than without those rules, but it's still rather imbalanced. The median hand will give one side a +4 advantage. I think the idea is that someone is supposed to fold during the betting if there is a large difference between the hands; this may reduce the number of uncompetitive chess games.

I think this variation may be somewhat useful for those who are *not* able to consistently win an early endgame position with a +2 or +4 advantage. Given that you probably don't get a lot of time to play the game, it may also be useful for practicing being in time trouble at the end of the game.

But there are probably better ways you could practice your endgame. In the end, it's worth playing if, and only if, you have fun.

# Answer
> 3 votes
I am referring to the following rules.

> My concern is that this is very unfair to one of the players as often even strong hands are not strong enough and end up being down a piece.

Let's calculate the material imbalance of one million random hands (sorry, it would have been too much hard for me to program the promotion and demotion rules).

```
import itertools
import random
import matplotlib.pyplot as plt
import numpy as np

deck = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,5,5,5,5,5,5,5,5,9,9,9,9]

cardCombinations = list(itertools.combinations(deck, 5))

arrayUnbalance = []

for i in range (1000000):
    randomHandWhite = random.randint(0, len(cardCombinations)-1)
    randomHandBlack = random.randint(0, len(cardCombinations)-1)
    unbalance = abs(sum(cardCombinations[randomHandWhite])-sum(cardCombinations[randomHandBlack]))
    arrayUnbalance.append(unbalance)

plt.hist(arrayUnbalance, bins=range(0,30,1))
plt.show()

```

The imbalance is always an even number. I think this is because all values are odd and all subtractions results in an even number.

* ~~~12%~~ ~14% of hands are equal and perfectly playable, but titled players could find them drawish.
* ~~~22%~~ ~27% of hands are unbalanced +2, and at a medium level the weak side can play for a draw to recover half of the pot, especially if you play the white pieces.
* ~~~66%~~ ~59% of hands are resigning positions at my level.

*After D M calcs with the full rules*

> Another reason I think this is especially due to the fact that you cannot see your opponent's pieces until they place all of them.

Where I play this is not the case. Players place the pieces in turns and you can see where your opponent is placing the pieces.

A minor consideration is that black has a slight disadvantage in this step of the game, as white's last piece can create forks and gain material (it is white's turn).

> Also, why can't we pre-move or have more than 2 pieces of the same "suit" or even place the pieces anywhere on our side rather than first 2 rows?

I agree pre-moves are important when you play a 3 minutes (end)game on a smartphone. I would like the site I play allow them.

A player with three bishops or knights would be a bit weird in my opinion. To place two bishops in the same color square is not allowed. I find it logical as promotions to bishops or knights are rare in chess.

To allow pawns to be placed on the 7th rank would alter the poker part. I like your idea of allowing the rest of pieces to be placed on all rows, the chess game would become more aggressive, but maybe this would give white a big advantage.

---

After that, I think a titled player could not profit his chess skill to beat a top poker player (maybe Nakamura would do). With a medium chess knowledge the poker player would beat the chess player as they do at Texas holdem.

Another problem I see is there are no online cash games at the moment. And what happens when you play poker with no cash? Everybody goes all-in with trash. You don't learn anything.

If you wish to play a serious game against a casual poker player and a 1800 rated chess player, you can add me as a friend on the app, my nickname is briest-man.

Ay, my level the game is funny. You can create threats when you place the (white) pieces and you have not a lot of time to finish the endgame. I profit my chess skill to beat players with my poker level, but weaker than me. I can stay on the site not paying any penny for the virtual chips. I wish there were cash games to play at low tables.

# Answer
> 2 votes
**2021 Update**: i think they've done more edits to the app and the game.

The app: The app was unfortunately not so good but I believe at least a little better now.

The game: I think the game is pretty balanced and fun and indeed requires skill in both chess and poker (well, maybe depends if the game has proper blinds and stuff). Thus, 'worth playing'. I think the best evidence for this is that there's already a choker cup, livestreamed by chess24.

Note that by giving the choker cup as an argument, this argument is more a posteriori than a priori or something. I'm not really arguing in terms of the rules of the game. I'm arguing like if there's a choker cup and Hikaru Nakamura, Alex Botez and Eric Rosen are playing this, then the game must be pretty balanced or whatever and thus 'worth playing'.

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


# Question
Title: What is the best move in this puzzle rush?
```
[FEN "2b2r1r/2k1q1b1/2p1p2p/1p1pPp2/pP1P1RB1/P1N5/2P1Q1PP/5RK1 w - f6 0 1"]
[starpPly "2"]

1. Bh5?

```

In this puzzle rush from chess.com, it says that Bh5 is the wrong move, although Stockfish shows it as the best. So what is the best possible move? It's the 17th puzzle and it is rated at 1124 ELO.

# Answer
Did black just play f5 before? Then the right move is exf6 en passant, Bxf6 Rxf6 Rxf6 Qe5+ and win the piece.

```
[FEN "2b2r1r/2k1qpb1/2p1p2p/1p1pP3/pP1P1RB1/P1N5/2P1Q1PP/5RK1 b - - 1 1"]
[StartFlipped "0"]
[StartPly "3"]

1... f5 2. exf6 Bxf6 3. Rxf6 Rxf6 4. Qe5+

```
> 24 votes

---
Tags: analysis, puzzles
---


title: Knight and 2 Pawn vs 3 Pawn Endgame

text:
# Question
Title: Knight and 2 Pawn vs 3 Pawn Endgame
I got into this endgame as black (thinking that its a draw) and finally managed a draw by repetition:

```
8/5p2/4p1k1/7p/4N2K/6P1/7P/8 b - - 0 45

```

(8th rank is at bottom) But the Lichess gives this position a +4.9. So, how to win such endgame as white ?

# Answer
Zugzwang.

OK, one word is a bit short for an answer. :-) Still, I would win that one for White probably on blitz time. Note that Black has only one passer and your knight easily can put a cork to that. Thus, with still one minute on the clock:

1. Play the N to f4 to kill Ph5.
2. Black of course will object to that, playing Pe5 in time.
3. Fine, then play the N to d3. The Pe5 now hangs.
4. Either he goes to e4, now you can catch the Ph5 and easily be back in time, or Kf6, same result.
5. Assume Black is lucky and manages to play Pe5, Pf4 without getting massacred. OK, same as before, the N gangs up on Pf4, he must go to f3, the K can capture it.
6. After that, back to the Ph5.
7. Finally, queen the remaining Ph2 and mate.

A final warning. As Black I will try to let you play the N to f4, and when you capture h5, I have the K on g6, play e5 and YOU are in zugzwang. With one minute on the clock, I won't ponder if g4 still is won after f4 (it most surely is, but panic on the streets of London), but rather play the cool Nd3 instead of Nxh5 and we're at point 6 of the plan again.

Black can do zilch about this plan, White can execute it without much thinking.

To learn:

* No swapping of pawns if you are up a figure.
* No rushing in endgame. (As I commented above, bof's plan Ng5, Nxf7 also wins but do that only if you trust yourself, and Black can also foil it with Pf6.)
* No allowing of muddling the waters when you have a technical win.
* Make a decent plan.
* Make it in easily executable parts.
> 8 votes

# Answer
Ng5 looks simple and should be game over. Then Nxf7 (sac) or Nxe6. If e5, Nxf7 Kxf7 Kxh5, and white is either going to stop the black e pawn with his king and maintain connected passers or promote first with his b (or a) pawn.
> 1 votes

---
Tags: endgame, knight-endgame
---


# Question
Title: A certain game with a knight promotion checkmate
I once remember (this happened 2-3 years ago) one of my friends showing me a game that was about 20 moves long. It was maybe a little longer, but it definitely ended in the middle game. It ended with a knight underpromotion checkmate, where the promoted knight both attacked the opposing king, and the knight also defended a rook that blocked off most of the king’s escape squares.

I am not 100% sure, but I think the winning player was down a whole lot of material before the knight promotion. I don’t remember whether the winning player was black or white.

I am sorry if this isn’t enough information to answer the question.

# Answer
> 2 votes
Due to prior knowledge, I scoured these three chessgames.com collections that I knew of. I found two games that match.

They do fit the bill of having the promoted knight protecting a rook. However, they're quite longer than 20 moves, are in the endgame, and have different material balances from what you think. It does help that they are recent games, relatively speaking, I'd say. So while they are similar, they may not be what you are looking for.

```
[Title "Gawain Jones-Danny Raznikov, Isle of Man Masters, Douglas Isle of Man, 10/12/2014"]
[FEN ""]
[startply "136"]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 Ng4 7. Bg5 h6 8. Bh4 g5 9. Bg3 Bg7 10. Be2 h5 11. h4 gxh4 12. Bxh4 Nc6 13. Nb3 Be6 14. Qd2 Qb6 15. Nd5 Bxd5 16. exd5 Nce5 17. c3 Ng6 18. Bf3 Rc8 19. Bg5 N6e5 20. Bxg4 hxg4 21. Rxh8+ Bxh8 22. O-O-O Kd7 23. Qc2 Rg8 24. Qf5+ Kd8 25. Be3 Qb5 26. Bd4 Qd7 27. Qh7 Rf8 28. f4 gxf3 29. gxf3 Bf6 30. Qe4 Rh8 31. f4 Qg4 32. Nc5 dxc5 33. Bxe5 Bxe5 34. Qxe5 Rh4 35. Rf1 f6 36. Qe4 Qd7 37. Qg2 Kc7 38. Qf2 Qb5 39. Re1 Rh7 40. Qg3 Kb6 41. b3 Ka7 42. Qf2 Ka8 43. Qc2 Rg7 44. Kb2 Qd7 45. Qe4 Qg4 46. Ka3 Qd7 47. Rh1 Ka7 48. Rh2 Qd6 49. Re2 Rg4 50. Qxe7 Qxe7 51. Rxe7 Rxf4 52. Rc7 Kb6 53. Rc8 Rf3 54. Kb2 Rd3 55. c4 f5 56. Kc2 Rh3 57. b4 cxb4 58. d6 Rh7 59. Kb3 Ka5 60. Rc7 Rh3+ 61. Kc2 Rh2+ 62. Kd3 Kb6 63. c5+ Kb5 64. d7 Rh1 65. Ke2 Rh2+ 66. Ke3 Rh3+ 67. Kd4 Rh1 68. Rxb7+ Kc6 69. d8=N#

```

---

```
[Title "Martyn Kravtsiv-Ding Liren, World Cup, Tbilisi Georgia, 9/8/2018"]
[FEN ""]
[startply "219"]

1. c4 Nf6 2. Nc3 e6 3. d4 Bb4 4. e3 O-O 5. Bd3 d5 6. Nf3 dxc4 7. Bxc4 c5 8. O-O cxd4 9. exd4 b6 10. Qe2 Bb7 11. Rd1 Bxc3 12. bxc3 Qc7 13. Ne5 Nbd7 14. Nxd7 Qxd7 15. Bd2 Ne4 16. f3 Nxd2 17. Qxd2 Rac8 18. Bb3 Bd5 19. Qd3 Qc6 20. Rac1 Bc4 21. Bxc4 Qxc4 22. Rc2 Rfd8 23. Kf2 h5 24. Qxc4 Rxc4 25. Ke2 b5 26. f4 f6 27. Kd3 e5 28. fxe5 fxe5 29. Rb1 a6 30. Rbb2 exd4 31. cxd4 Rdxd4+ 32. Ke3 Re4+ 33. Kf3 Rf4+ 34. Ke3 Kh7 35. g3 Rfe4+ 36. Kf3 Rxc2 37. Rxc2 Ra4 38. h4 Kg6 39. Rc6+ Kf7 40. Rc7+ Kf6 41. Rc6+ Ke5 42. Rc5+ Kf6 43. Rc6+ Kf7 44. Rc7+ Kg6 45. Rc6+ Kh7 46. Rc2 g6 47. Ke3 Kg7 48. Rc7+ Kf6 49. Rc6+ Kf5 50. Rc5+ Ke6 51. Rc6+ Ke5 52. Rxg6 Ra3+ 53. Kd2 Rxa2+ 54. Kc3 Ke4 55. Rg5 Kf3 56. Rxh5 Kxg3 57. Rh8 Ra4 58. h5 Kg4 59. Kb3 Kg5 60. Kb2 Rh4 61. Ra8 Rb4+ 62. Kc3 Rc4+ 63. Kb3 Rc6 64. Rh8 Rh6 65. Rd8 Kxh5 66. Rd5+ Kg4 67. Kb4 Kf4 68. Rd1 Ke3 69. Kc5 Ke2 70. Rd4 Rh1 71. Rd6 Ra1 72. Rh6 Kd3 73. Kb4 Rb1+ 74. Ka5 Ra1+ 75. Kb4 Kd4 76. Rh4+ Ke5 77. Rh5+ Kf6 78. Rh6+ Kg5 79. Rd6 Ra4+ 80. Kb3 Kf5 81. Rh6 Ke5 82. Rg6 Kd5 83. Rf6 Kc5 84. Rh6 Ra1 85. Kb2 Ra4 86. Kb3 Rb4+ 87. Ka3 a5 88. Rh5+ Kd6 89. Rh6+ Ke5 90. Rh5+ Kf6 91. Rh6+ Kg5 92. Ra6 Ra4+ 93. Kb3 Kf5 94. Rh6 Rg4 95. Rb6 a4+ 96. Ka2 Rb4 97. Rh6 Rb3 98. Rh4 Ke5 99. Rg4 Kd5 100. Rh4 Kc5 101. Rh5+ Kb4 102. Rh4+ Ka5 103. Rh5 Rf3 104. Rg5 a3 105. Rg4 b4 106. Rh4 Rf2+ 107. Kb3 Rb2+ 108. Kc4 a2 109. Rh8 Rc2+ 110. Kb3 a1=N#

```

---
Tags: checkmate, middlegame, pawn-promotion, famous-games
---


# Question
Title: Are there awards or titles for writing chess engines?
I recently found out that, in addition to the well-known titles for chess players, there are titles available for chess composers.

Is there such a thing as an award or title issued to those who have written especially good AI chess engines? I did some artificial intelligence scripting at university, and it occurred to me that I might be able to try out some of that neural net stuff to train up a chess engine that, while not quite reaching the level of world grandmaster, might win some local competitions or gain me some recognition on the regional coding circuit. Does such a thing exist?

I know that this is probably a pretty niche area, but if there are titles available for composers, it stands to reason that there might be some kind of recognition out there for those who have written some especially clever scripts (e.g. more than brute force "search the entire game space ten moves out" techniques that pretty much any programmer can write if they have enough time on their hands).

# Answer
No, there are not. Engine chess does not have a governing body to award titles. There usually are not any prizes aside from bragging rights, either.
> 1 votes

---
Tags: engines, titles
---


# Question
Title: Can you solve this unique chess problem of white's two queens vs black's six rooks?
```
[FEN "3Q4/7Q/3rp3/2rkr3/2rrr3/7K/8/8 w - - 0 1"]

```

I found this interesting and unique chess problem online, on the internet. Disclaimer: This is not necessarily a position from a game. It's just a beautiful composition wherein your objective as White is to checkmate the black king. White is moving from bottom to top and Black is moving from top to bottom.

This problem was made by Filip Bondarenko and published in Feenschach in 1960, although this version is cut one move short.

**White to move. Can anyone solve this?**

# Answer
It's checkmate in 20 moves. White's queens circle around the board giving checks, and Black interposes horizontally/vertically moving pieces. Black only has one choice because the other piece is pinned from the previous check. That goes well, until the pawn needs to move sideways:

```
[FEN "3Q4/7Q/3rp3/2rkr3/2rrr3/7K/8/8 w - - 0 1"]

1. Qb7+ Rc6 2. Qa5+ Rc5 3. Qb3+ Rc4 4. Qd2+ Rd4 5. Qf3+ Re4 6. Qg5+ e5 7. Qf7+ Re6 8. Qd8+ Rd6
9. Qb7+ Rc6 10. Qa5+ Rc5 11. Qb3+ Rc4 12. Qd2+ Rd4 13. Qf3+ e4 14. Qg5+ Re5 15. Qf7+ Re6 16. Qd8+ Rd6
17. Qb7+ Rc6 18. Qa5+ Rc5 19. Qb3+ Rc4 20. Qd2# 1-0

```
> 72 votes

---
Tags: endgame, problems, queen-endgame
---


# Question
Title: What's the idea behind delaying capturing the rook (25...Rd2) in Hug–Spassky (1973)?
I've been studying a series of games featuring the King's Indian Attack and in Hug–Spassky (1973)\[1\], I don't understand why White delays capturing the rook after 25...Rd2.

**Why play 26. Nd3?**

Is White avoiding the loss of tempo after (26. Qxd2 Qd8) or (26. Qxd2 Rad8)?

Instead, White plays 26. Nd3 prompting 26...Rxe2. I must be missing something since I don't see the idea behind 26. Nd3.

```
[Title "Hug (2440) - Spassky (2655), 1973"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[startply "50"]

1. Nf3 d5 2. g3 { A07 King's Indian Attack } c6 3. Bg2 Bf5 4. O-O Nf6 5. d3 e6 6. Nbd2 Be7 7. Qe1?! { (0.55 → -0.05) Inaccuracy. Nh4 was best. } (7. Nh4 Bg4 8. h3 Bh5 9. g4 g5 10. Nhf3 Bg6 11. Ne5 Nbd7) 7... h6 8. e4 Bh7 9. Qe2 O-O 10. b3 a5 11. a3 c5 12. a4 Nc6 13. Bb2 Re8 14. Ne5 Nd4 15. Qd1 Qc7 16. Nef3? { (0.00 → -1.29) Mistake. f4 was best. } (16. f4 Rad8 17. Kh1 Nd7 18. Ng4 Nf6 19. Ne5) 16... dxe4 17. dxe4 Red8 18. Re1 Nxf3+ 19. Bxf3 c4 20. bxc4 Bb4 21. c3 Be7 22. Qe2 Nd7 23. Nb3 Ne5 24. c5?! { (-1.33 → -1.93) Inaccuracy. Nd4 was best. } (24. Nd4) 24... Bxc5 25. Nxc5?? { (-1.77 → -4.79) Blunder. Bg2 was best. } (25. Bg2) 25... Rd2 26. Nd3 Rxe2 27. Bxe2 Nc4 28. Bf1 Qc6 29. Bc1 Bxe4 30. Nc5 Bd5 { White resigns. } 0-1

```

\[1\] Game with annotations by lichess.org

# Answer
> 5 votes
> Why play 26. Nd3?
>
> Is White avoiding the loss of tempo after (26. Qxd2 Qd8) or (26. Qxd2 Rad8)?

No, the idea behind Nd3 is to limit the losses. Black would respond to 26. Qxd2 with Nxf3+ forking the king and queen.

```
[fen "r5k1/1pq2ppb/4p2p/p1N1n3/P3P3/2P2BP1/1B1rQP1P/R3R1K1 w - - 0 1"]

1. Qxd2 (1. Nd3 Rxe2 2. Bxe2 Nxd3 3. Bxd3 {and white has limited the losses}) Nxf3+ 2. Kg2 Nxd2

```

After the sequence starting with Nd3 white is down a queen in exchange for a rook and a bishop. After Qxd2 white ends up down at least a queen for a rook.

# Answer
> 1 votes
I am not a strong enough player to be sure, but if White takes the rook with **26. Qxd2** then Black has **26...Nxf3+** with a triple attack on White's king, queen, and rook.

Hug would have seen this immediately and thus knew the queen was already lost. I'm not sure why Nd3 is the best move but Stockfish agrees.

---
Tags: analysis, learning, kings-indian-attack
---


# Question
Title: Why does castling in the Four Knights: Double Spanish opening inadvertantly stop Bxc3?
So I am currently working through Chess Fundamentals by Capablanca and he said something I find opaque: following 1.e4, e5 2.Nf3, Nc6 3.Nc3, Nf6 4.Bb5, Bb4 "5.0-0 an indirect way of preventing 5...Bxc3, which more experience or more study will show to be bad."

I have been trying to figure out why, if for whatever reason white does not castle (lets say 5.d3), then why is taking better for black? I looked all over for ways to exploit the king in the center, or ways to take away the white king's castling rights, but I have found nothing.

# Answer
One hundred years ago grandmasters, even the great Capablanca, were given to making sweeping judgments about opening positions without supporting evidence, often condemning moves that have been shown to be quite playable. In fact 5...Bxc3 is now considered a "book" move, though 5...O-O is probably slightly better. And as to 5.d3 making the exchange good, after 5.d3 5...Bxc3 is now considered roughly equal to other reasonable moves like 5...O-O or 5...d6.

BTW the Four Knights Game is often casually dismissed as a "drawish" opening, again without supporting evidence. If you study it and try it you'll find that many opponents who expect the more usual 3.Bb5 or 3.Bc4 are unprepared for it.
> 3 votes

# Answer
I think there is no simple answer to this question and you will develop understanding day by day.

In chess basically, the bishop is more valuable than the knight in an open position. When the black exchange the bishop with the knight, it would be a bad exchange. Furthermore, you can not take the e4 pawn. Example variant is

> 5 .. Bxc3 6.dxc3 Nxe4 7. Re1 d5 8. Nxe5

I am not an expert of 4 knights, but without taking a pawn, and giving a bishop for a knight would probably bad.
> 1 votes

---
Tags: opening, analysis, theory, capablanca, four-knights
---


# Question
Title: List possible moves for player - Haskell implementation
I'm trying to implement a function in Haskell that returns a list containing all possible moves for the player who's up. The function's only argument is a String composed of an actual state of the board (in Forsyth-Edwards Notation) followed by the moving player(b/w).

Notation example : rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w (starting board state)

So far I used a function to split the string into ranks, but I'm having a hard time coming up with an implementation.

Any tips?

# Answer
FEN is fine for unambiguous communication of a position (if you include castling and e.p. state too) but the internal representation should be as a board, with some kind of movement so you can efficiently check for legal moves, blocks, checks etc. Would hate to do all that with regex!

This quite a well-travelled area, and there must be much material online. You have made the choice to use Haskell here: what is the motivation for this? Are you trying to learn Haskell, or do you think it’s appropriate for certain aspects of a chess engine.

Chess is a finite directed binary graph, with each position just a node. There is certain machinery to reach that level of abstraction, but ultimately I would think a functional language like Haskell might really begin to show its worth when you have reached that conceptual level.

Depends also what you want your engine to do: find good moves, solve problems, analyse endgames, tablebases, retrograde analysis, support fairy chess. So please say more! :)
> 2 votes

---
Tags: software, computer-chess
---


# Question
Title: An aggressive opening for Black against 1. e4
I am a novice at chess. I am around 1400-1600 chess rating. I have struggled to find any sound aggressive openings for black against E4. As white I play the Scotch Gambit which I have great success with.

Can anyone recommend any sound openings for black that are aggressive and could you explain the theory behind it also? I prefer openings that don't need a lot of lines to remember.

# Answer
> 14 votes
White is one move ahead, and attacking. You *can't* be aggressive yet, or you'll just lose!

You have two choices: either you try to contain white, and when that is done and the position is equal, then you try to become active yourself. Or, you let him expand, but make sure you'll have your own trumps as well. The first way will lead to more or less symmetric positions, the second way is only possible if you make the position as asymmetric as possible: then he can have his trumps, and you can have yours.

The most famous asymmetric way of playing against 1.e4 is the **Sicilian**.

```
[FEN "rnbqkbnr/pp2pppp/3p4/8/3NP3/8/PPP2PPP/RNBQKB1R b KQkq - 0 4"]

```

Example Sicilian after 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4.

*If* white goes for this (he has plenty other options that are very strong too, black has other 2nd moves with the same idea), then he played 3.d4 to open the center, he'll have extra space, open diagonals for his bishops and great chances of an attack -- but you'll have your trumps too. You have 2 pawns vs 1 in the center, can move a rook to the c-file, and you have no weaknesses. You're *very far away* from having your own attack, but if white expands too much... BOOM. Not easy to play, but white has no way to simply control the game from here, he needs to attack.

Another way is the Pirc / Modern, characterized by putting a bishop on g7. With Nf6 in it's a Pirc, without it's a Modern. E.g.,

```
[FEN "rnbqk2r/ppp1ppbp/3p1np1/8/3PPP2/2N2N2/PPP3PP/R1BQKB1R b KQkq - 2 5"]

```

Again a very asymmetric position, white and black are doing very different things. But white has much more space, and he's looking for an attack. Black is thinking that he will be able to defend, and *then*, white will have thrown too many pawns ahead, leaving behind all kind of empty space... again, counter attack coming up, *if* black survives.

So those are ways to play for the counter attack; counter attack is only possible if you manage to weather the attack first.

Otherwise, forget about attacking for now, and try to get an equal position.

# Answer
> 8 votes
Against a king pawn opening, one of the most straightforward and aggressive ways to defend is the Scandinavian. If you don't want much theory, I would suggest the Bronstein (also called Pytel-Wade) variation:

```
[Title "Scandinavian, Bronstein variation"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.e4 d5 2.exd5 Qxd5 3.Nc3 Qd6 {This is the move that characterizes the Bronstein variation among the rest.} 4.d4 Nf6 5. Nf3 a6 {This is the usual position you'll find when playing Qd6. Simple development, nothing fancy.} 6. g3 Bg4 7. Bg2 Nc6 8. O-O O-O-O

```

This is an easy opening to play, without much (if any) theory, as black's plan is very easy: `Bg4`, `Nc6`, `O-O-O` and go crazy against almost any development scheme that white adopts. Definitely a line worth consideration, albeit a risky one. As white possesses as much counterplay as black, plus more development (as his dark-squared bishop doesn't need any pawn moves to get out of the first rank).

If you wish a more challenging option for white and not let him get his way so easily, you may try a variation of the Sicilian of your choice. To get the initial grasp of the Sicilian, I recommend the Taimanov variation, which is not extremely theoretical but needs some studying:

```
[Title "Sicilian, Taimanov"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 {This move order avoids studying the Rossolimo variation, which is a little annoying variation in my opinion.}

```

However, if you are looking for something crazy, the Pin variation (which I do *not* recommend for serious play, but you asked for an aggressive opening without too much theory...) is a very aggressive one, and there is only one line that's worth mentioning (which is really not much in means of theory volume). Despite this, this line is almost a refutation of the variation, so you may try to gamble your way out if white doesn't know what he's doing or die a horrible and painful way. Here you have an outline of the variation:

```
[Title "Sicilian, Pin variation"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Bb4 {This is the starting position of the variation. Not many people know the correct continuation for white, and this plays in your favor. However, against correct play this line is probably just losing.} 6. e5 Nd5 7. Bd2 Nxc3 8. bxc3 Be7 9. Qg4 O-O {Yes, here black's best option is to simply sacrifice the exchange. If white accepts, black has unquestionable influence over the dark squares, but he is still not in extremely good shape.} 10. Bh6 g6 11. h4! {This is the main tabiya of the variation. The discovery of this move has "doomed" the whole pinning the Nc3.} Qa5 {The only reasonable move is to look out for counterplay.} 12. Qg3 d6 13. Nb5 Nc6 14. h5 Nxe5 15. f4! {Here theory begins to get blurry, but this move unquestionably hands white the initiative and a very very dangerous attack.}

```

**Conclusion:**

* I recommend you try the Scandinavian and aim for messing things up in the early stages of the game. It is always fun playing for mating attacks and on these lines you'll certainly have many chances to do so.
* If you are a gambler and like risks and do not mind playing (almost-surely-)flawed lines, try the Pin variation. You will get a taste of what playing the Sicilian is, and maybe upgrade your repertoire to the Taimanov or other in the future.

# Answer
> 5 votes
SICILIANS. Most of variations in Sicilian defense are double-edged. The problem is I'm not sure if 1400-1600 is good level to play Najdorf or Dragon for example. Well, you can try. The problem is, your oponents are likely to not know theory very well. Would you have enough understanding to take adventage of not too accurate moves?

One "funny" variation I used to play is `1. e4 - c5 2. Nf3 - e6 3. d4 - cd4. 4. Nd4 - Nf6. 5. Nc3 - Bb4` This variation is rather BAD for black. But white has to know theory, otherwise you can easily equalize or even get adventage.

More solid (and times more complex) is Taimanov. A great book by John Emms was written on this topic. I would suggest this one.

Considering your opponent are \<1800 and I have faced players over 2000/2100 not knowing anything about above variations I would suggest you having a look at one of many of `1. e4 - c5 2. Nf3 - e6`. Take a look what fits your style.

You would be surprised how many people don't know anything about Sicilians with `e6`! Wish you good luck with your reppertoire!

# Answer
> 5 votes
If you want an aggressive opening which constantly attacks at the white king I would recommend Latvian Gambit. p.s. In the Scandinavian it is not necessary to capture on d5 with the queen; you can play the Icelandic Gambit and many other cool gambits after 1.e4 d5 2.exd5 Nf6?! which leads to many interesting lines.

# Answer
> 4 votes
1400-1600? Just responding e5 will get you aggressive, open games more often than not. The chances that you'll actually wind up defending the kind of theoretical, slightly inferior cramped positions that result from best play in the open game are very low. Your opponent will probably just trot out pieces and allow you to equalize or even seize the advantage pretty easily if you know what you're doing.

The suggestion of the Scandinavian is also not bad. I don't like the Sicilian at this level because it will probably just degenerate into some kind of irregular closed Sicilian that's fine for Black but hardly "aggressive."

Honestly, worrying in detail about the "style" of opening you should be playing at this level is a symptom of misplaced priorities. Games at this level are won by 2- and 3- move tactical shots. That's another reason to favour e5, it leads quickly into the kind of games where these shots are most prevalent, without a lot of byways.

# Answer
> 2 votes
The Sicilian defense is probably your best choice, since you want aggressive play. However, there is a lot theory and lines but probably knowledge of a few lines and some plans is good enough for your level. I play the scotch gambit as white as well. I play e5 however, which has a lot of aggressive lines too.

# Answer
> 2 votes
Give me something sound but aggressive. Give me the moves, too, but I don't want to learn lots of lines.

You'll save maybe years of study time after you figure out that all you need to get out of the opening is a playable middlegame (most often attributed to Teichmann).

You're not a 1400 player because you're bad at openings, you're a 1400 player because you're bad at tactics. You can play an opening perfectly, then drop a rook to a two-move combination, you lose. In fact, you can wheel your entire openings library up to the board and play with open books, and it won't help you a bit. Your opponent will step out, and make you think for yourself, and even you reach the magic +=, you're on your own.

Openings literature, and whatever anyone gives you on Stack Exchange, is a map into the middlegame forest, where you wander lost unless you know the path to the other side of the forest (the endgame). You can't play a proper middlegame unless you can recognize a favorable or unfavorable ending on the horizon, because how are you supposed to know whether to complicate or simplify? If all you really need from an opening is a playable middlegame -- one with rough equality in center control, development, and king safety -- then it's a matter of judging the positional imbalances better than your opponent does, while being better at tactics.

If you want a recommendation for Black, consider this: If I gave you the White pieces and two moves in a row to the start the game, which would those be?

Was it e2-e4 plus d2-d4? Very good. So go ahead and do that as Black with the QP Countergambit: 1. e4 e5 2. Nf3 d5. It's not popular, so other people will say 'oh don't do that, it sucks, play the Najdorf', but they're obeying grandmaster fashion more than having listened to thousands of club level players go through this same thing. If White plays well against that, he'll wind up with a space advantage at the end of the opening, but White's going to emerge from the opening with a little something, no matter what you do. If you start with the e- and d-pawns two squares forward, you're giving yourself a shot at the center and you don't have to make any more pawn moves to complete your development.

# Answer
> 1 votes
I would concentrate on maintaining a strong center. e4 Match it with e5. THe different moves in the the beginning should be a move to control the center. Pawn moves or knight moves. Develop knights before bishops. Don;t get your queen out too early. Ther;s a lot of players that think that they can dominate the board with their queen. Instead of developing they're having to move their queen because it's under attack. Castle early. #1in the game is kingsafety.

# Answer
> 1 votes
Alekhine's Defense (1. e4 Nf6) is a very agressive way to play for the win. It's not uncommon to see a line that draws less than 5-10% of the time.

# Answer
> 1 votes
I've been playing the Alekhine for a while now, and unless white plays it safe, you can get a very agressive game. The idea is for you to develop your pieces quickly while white wastes its time sending pawns up front. I personally enjoy playing lines with my light squares bishop on f5. Then (especially in fast paced games) you can often get a nice fork with your knight on c2.

As for the scandinavian, I believe it's quite bad if you want to get active pieces (which is usually necessary for agressive play). The only way you'll get a sharp game out of this opening is if you manage to play a gambit (icelandic or scandinavian). But you'll rarely get a chance to actually play that.

In the end, I believe that you can turn any opening into an agressive opening. You just have to play agressively. The question then turns into: How do I play agressively? Here are some ways of doing that: try to open lanes for your rooks (sometimes at the cost of a pawn. Keep your pieces active. Try to set up outposts for your knights. Keep your bishops on open diagonals.

Lastly, if you want to make sure you get a very sharp game with agressions from both sides. Just castle on the opposite side! No matter what opening you choose.

# Answer
> 0 votes
`Goldsmith Defense` I do not know this one could be more aggressive, but I feel like kind of strategical.

The straightforward Answer to your Question could be, `King's Gambit`, `Polerio Gambit`, I played this games in my chess online, this leads to much chaos in center of the board, so the game will be either wild or its of more precautionary moves which are time consuming. And still Knights are ready for Scottish as you specify, but will bring up complication and could open up Chess Mega Database and could've different name, based on how much knights out of four comes up in front.

Here is one sample game for `Goldsmith Defense`. In this game, white had blundered and lost the Queen. I do not know how effective the other moves are, however I personally feel, its comparatively effective.

```
[fen ""]
[Event "Live Chess"]
[Site "Chess.com"]
[Date "2018.04.16"]
[White "Joshyopl"]
[Black "BramStokers"]
[WhiteElo "992"]
[BlackElo "1162"]
[TimeControl "600"]
[Termination "game_result.won_by_resignation"]
[Result "0-1"]
[CurrentPosition "8/5kp1/p1pb4/6B1/3pq3/8/PPPK1n1r/R7 w - - 0 23"]

1.e4 h5 2.Nc3 d6 3.d4 f5 4.Nf3 fxe4 5.Nxe4 Bf5 6.Bd3 Nh6 7.h3 Nc6 8.g4 hxg4 9.hxg4 Bxg4 10.Bb5 a6 11.Bxc6+ bxc6 12.Rh4 e5 13.Nfg5 Bxd1 14.Kxd1 exd4 15.Ne6 Qxh4 16.Nxc7+ Ke7 17.Nxa8 Qxe4 18.Bg5+ Kf7 19.Nb6 Ng4 20.Nc4 Nxf2+ 21.Kd2 Rh2 22.Nxd6+ Bxd6  0-1

```

# Answer
> 0 votes
I would recommend 1. e4, e5 for your level. In general, aim for lines that play Bc5 and d5 as soon as possible. Against the Ruy you have both the classical and the Archangel Defence which will stick to those basic ideas. If you want something more aggressive try the Schlieman.

There's also the Latvian and believe it or not there are some very aggressive lines in Petrov's defense like the Stafford gambit

Most lines in the Sicilian are aggressive.

Hyper-modern openings like the Pirc, modern and Alekhine's tend to be more aggressive although you need to understand that attacking the center is your first goal.

The Nimzovich is similar to the above although the types of positions can vary.

There are some lines in the Scandinavian Defense. The main lines aren't that aggressive but there are some off-beat lines like the Portuguese Gambit that are.

# Answer
> 0 votes
The Sicilian Defence might be suitable for you too. 1.e4 c5 2. Nf3 e6 3.d4 cxd4 4.Nxd4 Nf6
You might try the black lion too. You can be passive or aggresive depending on how you play!

# Answer
> 0 votes
Try the Stafford Gambit; not famous amongst GMs but for beginners and intermediate its a gambit which gives a lot of options.

```
[FEN ""]

1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nc6

```

https://www.youtube.com/watch?v=s0Ibh5B0ooo&t=5s

https://www.youtube.com/watch?v=zd98Nd-Cdfc

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


# Question
Title: Can you solve this chess problem of a lone knight against numerous opposing pieces?
```
[FEN "8/1nq5/bppp4/1p1k1K1N/1rrp3b/2pp2p1/8/n7 w - - 0 1"]

```

I found this interesting and unique chess problem online.

Disclaimer: This is not necessarily a position from a game. It's just a beautiful composition wherein your objective as White is to checkmate the black king. White is moving from bottom to top and Black is moving from top to bottom.

This problem was composed by Hungarian Engineer Ottó Bláthy.

It's white turn and it's mate in 12 moves. Can you find the winning move continuation for white?

# Answer
> 24 votes
OK

* The check must come from the knight (D'uh!)
* The black king must be on c5 for the mate
* The white king must be used to cover any empty squares to the right of the black king - thus the white king must move, thus there must be at least one non-checking move
* On a non-checking move Black can try to release the prison by Ra4
* The only way white can cover this is for the winning check to come from d3, as this covers b4 and the knight can not be captured there (unlike a6 after the rook moves)
* When white makes the non-checking move he must be in a position to deal with threats from black, in particular the black queen, and checks from the black knight on c7 and the black bishop on h4
* If on the non-checking move white plays Ke6 directly the knight check from d8 will break the prison
* Thus the king must go to e4, attracting the black pawn to d5 with check, after which, if the black queen has been eliminated, the white king can go Ke6 Nd8+ Kd7 and it can't at that point be driven away

Putting this all together leads us to

```
[Event ""]
[Site ""]
[Date "????.??.??"]
[Round ""]
[White ""]
[Black ""]
[Result "1-0"]
[FEN "8/1nq5/bppp4/1p1k1K1N/1rrp3b/2pp2p1/8/n7 w - - 0 1"]

1.Nf4+ Kc5 2.Ne6+ Kd5 3.Nxc7+ Kc5 4.Nxa6+ Kd5 5.Nc7+ Kc5 6.Ne6+ Kd5 7.Nf4+
Kc5 8.Ke4 d5+ 9.Ke5 Bf6+ 10.Ke6 Nd8+ 11.Kd7 Ra4 12.Nxd3# 1-0

```

I think that's it, though I can't see at the moment what the Black Knight on a1 is doing

---
Tags: endgame, problems, chess-variants, knight-endgame
---


# Question
Title: Reasons why castling may be the only winning move
I recall at least one game of mine where my last move was castling (around move 20 or so :-), it saved my ugly posterior, it was the only move and we immediately agreed on a draw after that. (Do not try this at home, kids.)

I see the following ways of castling being the only winning move.

* Retro: Under some convention, one side castles to prove the other can't.
* Tactical 1: Again, the king's posterior is on fire, and after that is solved, material wins. (Happened.)
* Tactical 2: Double attack on a stupid incoming Rb2 and Kd8 - yes, that happened more than once.
* Tactical 3: E.g. after some Nxf2 against the bK, with great shocking value. Ditto. So lets file everything else in this spirit under "Various Tactical".
* Positional: This is the only way to get the rook past the king and out of the pawn forest. (Very study-like. Probably never happens in a game.)

What are other ways in which castling may the only winning move in any given position?

# Answer
> 2 votes
Castling is an incredibly useful in chess: three moves in one. So we don't have to hunt far for reasons why it can be the best move strategically.

One common comparison is between the castling and the rook move to the d file or f file. Basically the king may need to move offensively, or defensively:

* to cover a flight square for bK,
* to attack a pieces (castling can be double attack),
* to avoid being checked/mated,
* to get out of the way so that the rook delivers check or can move.

In basic retrograde analysis, castling is used as OP pointed out, to deny the opponent's castling in certain situations.

In more sophisticated retrograde analysis, under the A Posteriori condition one player captures e.p., which would not normally be allowed, but a later castling "proves" that the e.p. was in fact justified as no other move could have been made.

In Dead Reckoning, castling may be the only way to keep the game alive, even if the result of the problem is in the end a draw. This also may allow the legality of castling to be deduced through retrograde analysis, without using the conventions. It is not normally possible to reason positively about castling using R.A.

In an antique version of the conventions, it was thought that castling would reset the counter for draw by 50 moves. So a few problems by Plaksin exploit this trick. This is still a matter of controversy even today.

There are also joke problems involving "playing at odds" so one player is missing a rook, but is still allowed to castle with the king moving twice, even though no rook actually moves. I don't know whether occupation of the vacant corner square would be enough to demolish the castling right, generally not, as some of these problems have a rook on the haunted corner square which did not originate there, either coming from the other side or promoting.

I'm aware this is a all bit dry so far, but we could find examples of all of these ideas if folk are interested.

---
Tags: problems, castling, puzzles
---


# Question
Title: Josh Waitzkin on trading pieces ('the art of the trade')
**Based on**: Josh Waitzkin Chessmaster Strategy Section 6 "The Art of the Trade." A video can be found here.

```
[Event "From Josh Waitzkin Chessmaster Strategy Section 6 'The Art of the Trade'"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "-"]
[Black "-"]
[Result "*"]
[SetUp "1"]
[FEN "r2q1rk1/p4ppp/1p2p3/2p5/2Pp4/PP1Pn2P/3QPRP1/RN4K1 w - - 0 1"]

1. Nc3

```

**Situation**

1. Josh says "2 possible solutions" are a4 and Qc1. Technically, he doesn't say they are the only possible solutions.
2. My thought is to play Nc3 in this position. The chess.com says engine says Nc3 is the best (as in not unique) move.

* Actually, I probably would've done something like b4, but Josh really said that one has to calculate several moves ahead. So, after some deep calculation, I came up with Nc3. I figure the idea is that you realize that black's knight has only 1 defender and then you calculate this counter-intuitive move of seemingly hanging your knight to see if you can really pull off this knight exchange (if black were to attempt to exchange), among others.

3. It turns out Josh didn't even seem to do calculations with either a4 or Qc1. He just laid out plans assuming Black wouldn't make any move.

**Questions:**

1. Actually, is Qc1 is merely "good"? 3 of the best moves that the chess.com engine says (either by saying the move is best or by telling what is an alternative) are Nc3, Qa2, and a4. Is Qc1 strictly inferior to Nc3, Qa2, and a4, and, so, Josh is actually wrong here to prefer Qc1 to a4?

* 1.1. Josh says a4 weakens white's pawn structure. Good point, but I don't know. The engine says Qc1 is just 'good'.
    * 1.2. Well I think the only 2 queen moves here are Qc1 and Qa2. I guess Qa2 is more active than Qc1. I don't know.
    * 1.3. Another thing to note: Maybe Josh mistakenly said Qc1 instead of Qa2. After this correction, perhaps we can then talk about a4 vs Qa2 and then say Qa2 is better.
2. Wait so what exactly is the calculation here? I was expecting we do (WOLOG the Qc1 thing) Qc1, think of black's move, do a response, etc. In the end Josh just showed how the white knight could go Nd2 to Nf1.

# Answer
> 3 votes
Since you explicitely requested an answer...

I don't own that Waitzkin book, but merely judging from your excerpts his pedagogical talents are as doubtful as White's position here :P

First of all, Black might cement in his octopus on e3 with e5, f5, f4, after that an exchange on e3 makes White's plight only slightly better. Insofar your 1.Nc3 makes very much sense, since Black is a move short for the above plan now. But tactics always trumps strategy (which is what Waitzkin misses to highlight - also your other question, which you asked me to contribute on - maybe later :-) - is highly tactical in nature), and the critical line is of course 1...dxc3 2.Qxe3 Qd4. White won't exchange since a protected Pc3 would be a disaster in the endgame. So, 3.Qc1 a6 (Black wants to cement with b4 then) 4.a4 b5 5.cxb5 axb5 6.axb5 Rxa1 7.Qxa1 c2! 8.Qc1 Ra8!! 9.e3(!) Ra1!! 10.exd4 Rxc1+ 11.Kh2 Rh1+! 0-1. This line might have more holes than an Emmentaler as I calculated it even without a board (and 2350 was my ELO 30 years ago...), but it should show you the tactical dangers after 1.Nc3. It might thus well be that objectively White must grin and bear it and play Qc1,Nd2,Nf1 and play possum awaiting the incoming pawn storm at the kingside. a4,a5,axb6 exchanges a rook but then only Black invades the queenside (as long as the Ne3 is present, the Rf2 is factically out of play).

Lessons learned: If a GM says "play X", it might be he has subconsciously calculated a lot of Y that is quite as relevant as long-time positional considerations. And you rarely find those lines explicitely in a textbook. ("Hey, why should I axe trees for the lines after Y? It *obviously* loses after 10 moves!")

P.S. I wouldn't play White even if Waitzkin gave me five quids :-)

---
Tags: strategy, chess.com, trading
---


# Question
Title: Josh Waitzkin chessmaster mastery quiz - spatial advantage, trading bishops
Update: The computer aspect of this can be answered with showing more lines such as in the lichess engine where h6 is slightly preferred to f5.

---

**Based on**: Josh Waitzkin Chessmaster Strategy Section 7 - the mastery quiz.

**Position**:

```
[Event "From Josh Waitzkin Chessmaster Strategy Section 7 - the mastery quiz"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "-"]
[Black "-"]
[Result "*"]
[SetUp "1"]
[FEN "rn1qn1kr/p2bppbp/1p1p2p1/2pP2PP/4PP2/2P1BN1B/PPNQ3K/4RR2 w - - 0 1"]

```

**White to move. I think h6, but Josh says f5.** I could swear that when I did this earlier, the chess.com engine said that they were both best moves. Anyway, now it says f5 is an **inaccuracy**. But at least it says to do f5 after h6, assuming Black plays Bf8. (link to screenshot)

1. **Is Josh wrong about f5**? Actually Josh even explains how Black's position is bad after f5-gxh5, but gxh5 is precisely what the chess.com engine considers a best move.
2. For h6-Bf8-f5, the chess.com engine says that Bf8 is only a good move and that Bxh3 is best. Bxh3 costs Black 2 pawns, but I guess does relieve some of the pressure of White's spatial advantage. **Is Bxh3 really the best or at least strictly better than Bf8?**

* I'd think maybe it would come down to preference/playing style. Or idk. I would consider Bxh3 an option if this was just 1 pawn. (Josh actually has an example earlier about giving up a pawn for the sake of relieving an outpost or spatial advantage.) But this is 2 pawns!

# Answer
My approach:

Black stands terrible, and h6 like you suggested is the only chance to muddle waters as a rook line against the white king is opened. And in this variant, I would rather let the Bh3 live for now: It's rather a liability with the pin than the rook giving a plain check. Also, White threatens h6 followed by more pawn moves, which would completely wall in Black. White can then rip up the queen side and play with effectively a rook up.

The exchange Bxh3 is good for Black on general principles, but as the Germans say, the music plays elsewhere!

Oh, and I wouldn't think a second on f5. After pawn exchange, h6, Nh4, Bg1 Black even is worse than before since now f5 and e6 are weak too.

Another position I'd play for the weaker side only at gunpoint...

EDIT: Sorry, I completely misunderstood: It's the *White* moves f5 and h6 Josh is talking about. Well, in that case:

You can wall in Black with h6, but f5 must be a followup, otherwise he might break out with e6 (which he can't after f5, even if e6 ist protected, because White simply plays f6. It doesn't matter that much if the bishops are exchanged, and on f5 I still would go for the kamikaze answer h6 (it's the last straw against being rolled over), thus again, first h6, then f5. Of course Josh *and* the engines might already have calculated that 1.f5 h6 is as hopeless as anything else, but I'm thinking practical.

Note that my generic comments on the position still hold.
> 2 votes

# Answer
> Josh says f5 ... Is Josh wrong about f5?

Yes, although black's position is terrible in any case.

If we look at the initial position and try and assess a number of things are immediately obvious:

* White has a lot more space
* All the pieces and all the pawns are still on the board

We can also say:

* White has completed development
* Black still has several pieces on the back rank and unless black can open the h file the rook on h8 is doomed to a miserable life in the near future

So, white has a very big advantage, probably close to winning.

The first two points (space advantage plus all 32 pieces still on the board) mean that it is much easier for white to move the pieces around and very difficult for black. Black's pieces get in the way of each other and there just isn't enough space in the black position for black's pieces. For black, knights are also better than bishops at the moment.

So, what can black do? Well piece exchanges would be very nice. They would create more space in black's position and make it less cramped.

Exchanging bishops would be particularly nice because, as luck would have it, the g7 bishop is occupying a square which would be great for the knight stuck on e8 and the d7 bishop is on a square which would be better for the b8 knight.

With all that in mind the pluses of h6 stand out. Bf8, the only move to not immediately lose material, firmly and further entombs the rook on h8, keeps all the pieces on the board, puts yet another piece on the back rank and moves the bishop off what is the best available diagonal for it to a dead-end square with no prospects. It becomes not much more than a "tall pawn".

What about f5? That allows Be5+, either immediately, or after a zwischenzug like gxh5 or Bc8 (clearing d7 for the knight). Let's look at what would likely happen after an immediate Be5+ and evaluate the resulting position:

```
[fen "rn1qn1kr/p2bppbp/1p1p2p1/2pP2PP/4PP2/2P1BN1B/PPNQ3K/4RR2 w - - 0 1"]

1.f5 Be5+ 2.Bf4 Bxf4 3. Qxf4 Ng7 4. h6 Nh5 5. Qh4 Bb5 6. Rf2 Nd7

```

What you have is chalk-and-cheese. Suddenly black's pieces can breathe. Black is still much worse. The rook on h8 still has no prospects but two more pieces are off the back rank and a bishop which was going to be useless has been exchanged off.

> Bxh3 costs Black 2 pawns

Nonsense! I think you are making the mistake of confusing the beginner's "point count" system of 1 point for a pawn, 3 points for a bishop with the real world. There is no way the black bishop on f8 is worth anything like 3 points. Similarly the white pawn on h6 is worth a lot more than 1 point.

> Is Bxh3 really the best or at least strictly better than Bf8?

Again let's try looking at a line where black follows Bxh3 with the Nxg7 immediately (the line where black plays Bxf1 is also possible although that puts black one rook exchange closer to a lost endgame) to see what is really involved:

```
[fen "rn1qn1kr/p2bppbp/1p1p2p1/2pP2PP/4PP2/2P1BN1B/PPNQ3K/4RR2 w - - 0 1"]

1. h6 Bxh3 (1...Bf8) 2. hxg7 Nxg7 3. Kxh3

```

After 1...Bf8 white has a really obvious plan to take advantage of the weak long diagonal and the monster pawn on h6 - c4, b2, line up the bishop and queen on the diagonal, mate. Alternatively, just leave black effectively a rook down (the piece on h8 is useless) and just break through in the center and mate black that way.

Going back to "beginner's point count" that rook is worth a lot closer to 1 point than 5. Once you get past beginner level you have to value your pieces according to what they can do now and in the near future.

After the sequence ending 3. Kxh3 those threats have disappeared. Black has an outpost for the knight on h5. Black might entertain hopes of playing h6 to open the h file and give the rook on h8 a purpose. Granted the position is still lost but at least there are prospects of counterplay and putting up a fight.
> 3 votes

---
Tags: strategy, positional-play, chessmaster, trading, waitzkin
---


# Question
Title: SCID vs ChessBase - play, analyse, visualization - ubuntu
Please help me or give me the correct terms to find it out.

What I want is:

* Play chess against an engine or repeat an existing game
* For my current move, I want an analyser to analyse my move, and a visualiation (not only text) to show me (better) alternatives.

What I tried:

* I installed SCID, with Stockfish, and loaded some PNG games or, doing: 'serious game' and play against stockfish
* I can see some analysis text running at a window. However, that is sort of exhausting. What I want: having an arrow that shows me what to move where; after I have done my move. Either by: analysing my move, and showing a better alternative. Or, showing me what the player (whose game I just play) was doing

My questions: how is it called, what I want? Does this exist, especially a visualization?

It is not necessary to use SCID, however, I failed to install SCID vs PC and Lukas Chess.

# Answer
I suggest that you simply use a browser, and play online at chess.com, lichess.com, or chess24.com. While chess.com and chess24.com have paid versions too, all three have the ability to create an account, and play online, including against computers.

You also have the option to use online engines to analyze your games.
> 2 votes

# Answer
try Lucas chess. It's free and works in windows and Linux using wine. It has a tutor option that is really visual and also many engines you can select based on your rating level https://lucaschess.pythonanywhere.com/
> 1 votes

---
Tags: analysis, chessbase, scid, linux, visualization
---


# Question
Title: Can you solve this chess problem of king and pawn against all opposing pieces?
```
[FEN "8/8/8/2p5/1pp5/brpp4/qpprpK1P/1nkbn3 w - - 0 1"]

```

I found this interesting and unique chess problem online.

Disclaimer: This is not a plausible position from a game, however it is legal. It's just a beautiful composition wherein your objective as White is to checkmate the black king. White is moving from bottom to top and Black is moving from top to bottom.

This problem was composed by the Hungarian Engineer, Ottó Bláthy.

It's white's turn. Can you find the winning move continuation for white?

# Answer
So white obviously has to start with

> 1.Kxe1 because otherwise the black knight escapes. Now black can only play Qa2-a1-a2, and white can't move the king anymore or black will immediately break out.

Then,

> We want to promote to a knight and give checkmate. If the rook on b3 were undefended, we can do it from there. (d3 will always be defended by the rook).

> So we remove the defending pawn(s), and have to play Nxb3# *when the queen is on a1*. Since the knight always moves to squares of alternating color, and so does the pawn after the first move, and so does the queen in this situation, all we need to do is to move it to a square of the opposite color of the queen on its first move, and it will work out.

> But the order we take the pawns is important! If we take c4 first, then black can later choose to either play c5-c4 or omit it, thereby causing our knight to be on the wrong color square at the wrong time. So first c5, then c4, then b3.

So

```
    [FEN "8/8/8/2p5/1pp5/brpp4/qpprpK1P/1nkbn3 w - - 0 1"]

1. Kxe1 Qa1 2. h3 {Queen is on black, so the pawn goes to white! Now we keep it that way} Qa2 3. h4 Qa1 4. h5 Qa2 5. h6 Qa1 6. h7 Qa2 7. h8=N Qa1 8. Ng6 Qa2 9. Ne5 Qa1 10. Nd7 Qa2 11. Nxc5 Qa1 12. Na4 Qa2 13. Nb6 Qa1 14. Nxc4 Qa2 15. Na5 Qa1 16. Nxb3#

```

(moves stolen from Glorfindel as he was slightly faster, but the reasoning is mine ;-))
> 12 votes

# Answer
First,

> White takes the single mobile Black piece: 1. Kxe1

Then

> Black can only move their queen back and forth between a1 and a2.

Meanwhile

> the white pawn promotes to a knight, captures the c-pawns and then the b3 rook.

```
[FEN "8/8/8/2p5/1pp5/brpp4/qpprpK1P/1nkbn3 w - - 0 1"]

1. Kxe1 Qa1 2. h4 Qa2 3. h5 Qa1 4. h6 Qa2 5. h7 Qa1 6. h8=N Qa2 7. Ng6 Qa1 8. Ne5 Qa2 9. Nxc4 Qa1 10. Na5 c4 11. Nxc4 Qa2 12. Na5 Qa1 13. Nxb3#

```

However,

> Black can also play 10... Qa2 and the knight is unable to lose a tempo. The king is unable as well (because he needs to keep the e2 pawn under control); white's only piece capable of losing a tempo is the ... pawn, by not doing a double step on move 2!

So let's try

```
[FEN "8/8/8/2p5/1pp5/brpp4/qpprpK1P/1nkbn3 w - - 0 1"]

1. Kxe1 Qa1 2. h3 Qa2 3. h4 Qa1 4. h5 Qa2 5. h6 Qa1 6. h7 Qa2 7. h8=N Qa1 8. Ng6 Qa2 9. Ne5 Qa1 10. Nd7 Qa2 11. Nxc5 Qa1 12. Na4 Qa2 13. Nb6 Qa1 14. Nxc4 Qa2 15. Na5 Qa1 16. Nxb3#

```
> 16 votes

---
Tags: endgame, problems, tempo
---