# Question
Title: How many former Russian players have moved from RUS or FID registration to another country since the May 2023 offer?
> "most are likely to do so Do you have any sources for this? "

The quote comes from a comment made by Allure to this post of mine where I claimed:

> FIDE have made it possible for Russian players to move cost-free and without delays to the European federation of their choice and most are likely to do so.

Of course I didn't have inside information but now that the 31st August deadline has passed we can see how many have already taken advantage of the offer and changed federation for free.

# Answer
> 3 votes
Using the data in the FIDE rating database here is a list of the 21 Russian players rated above 2600 who were registered as RUS in February 2022 (when the conflict started) and who changed their federation from RUS by 31st August 2023.

**FullName FIDEID Code Rating**
Vitiugov, Nikita 4152956 **ENG** 2726
Andreikin, Dmitry 4158814 FID 2724
Esipenko, Andrey 24175439 FID 2714
Fedoseev, Vladimir 24130737 **SLO** 2704
Alekseenko, Kirill 4135539 **AUT** 2702
Sarana, Alexey 24133795 **SRB** 2685
Svidler, Peter 4102142 FID 2683
Predke, Alexandr 24107581 **SRB** 2682
Oparin, Grigoriy 24125890 **USA** 2681
Sjugirov, Sanan 4189302 **HUN** 2680
Najer, Evgeniy 4118987 FID 2661
Inarkiev, Ernesto 4162722 FID 2659
Demchenko, Anton 4160258 **SLO** 2654
Malakhov, Vladimir 4120787 FID 2652
Rakhmanov, Aleksandr 4173708 FID 2640
Motylev, Alexander 4121830 **ROU** 2633
Chigaev, Maksim 4108116 **ESP** 2631
Paravyan, David 4194985 FID 2617
Antipov, Mikhail Al. 4107012 FID 2615
Goryachkina, Aleksandra 4147103 FID 2610
Lysyj, Igor 4150120 FID 2603

7 out of the top 10 took advantage of FIDE's offer and changed to another country federation. 10 out of the top 21 did so.

---
Tags: fide
---


# Question
Title: What is the easiest way to win this endgame in a blitz game?
Say you're in a blitz game and you and your opponent both have 45 seconds left.

```
[Title "White to move"]
[fen "6k1/3p2pp/p7/1pPq4/1P6/P5RP/6PK/8 w - - 0 45"]

```

My question is how would would you go about winning this with black and what would you do with white to try to draw?

# Answer
> 1 votes
Black's strategy is very straightforward. Push a5 to break up white's queen side pawns, win two of them leaving the d pawn as a passer and then queen it. There's not much white can do.

White should probably start with Rf3 to anchor the rook and cut off the black king from the center but it won't stop black's simple plan. It could look something like this:

```
[fen "6k1/3p2pp/p7/1pPq4/1P6/P5RP/6PK/8 w - - 0 45"]

1. Rf3 a5 2. bxa5 Qxc5 3. Kh1 Qc1+ 4. Kh2 Qc7+ 5. Kh1 Qxa5 6. Rd3 Qe1+ 7. Kh2 Qe5+ 8. Kh1 d5

```

---
Tags: endgame, strategy
---


# Question
Title: Why is Nh6 a mistake here? Why is Nf6 the best move?
I'm analyzing this game between me and Stockfish Level 1 on lichess.org: https://lichess.org/0SvUBEu0/black#4

With Nh6 I was trying to counter a possible Bxf7+. Without Nh6, the King would have to move making castling impossible.

On the other hand, what is Nf6 supposed to do? Nf6 is the engine recommended move here.

# Answer
> 4 votes
In the opening it is recommended that you develop you pieces towards the center, especially the knights which are much more active there than on the edge. So 2...Nf6! is better than 2...Nh6?

Notice that the knight on h6 cannot go anywhere but back to g8: g4 is controlled by the Qd1 and f5 by the Pe4. True, you protect f7, but that pawn is already protected by the king (3.Bxf7?? is bad in any case because of 3...Kxf7).

Moreover the Nh6 will soon be attacked by the Bc1 (after d2-d3 or d2-d4) and an exchange on h6 would spoil your pawn structure after you take back with ...gxh6. It becomes quite risky to castle short because the isolated doubled pawns on the h-file are not a good shelter for your king.

On the other hand, from f6 the knight attacks the Pe4, controls d5 (to prevent White from using that square, or to push d7-d5 later), will be a good defender of your king after you castle. It also stops White from reinforcing the attack against f7 (no Qh5, and Qf3 is blocked from eyeing f7) if that's what worried you.

All in all, 2...Nf6 is a much better move than 2...Nh6.

# Answer
> 1 votes
B:f7 is not a threat at this moment since white pieces have no way to join the attack immediately and the black King can safely retreat.

Thus the best strategy is to developed pieces actively. The move Nf6 is ideal for various reasons including the fact that it controls the squares g4 and h5 which are the natural squares the white Queen could use to attack the King.

Also, the Knight on f6 supports a future d5 push by black which can be a natural plan. Remember: one of the basic goals of an opening is to exert a control of the central squares.

# Answer
> 1 votes
Control of the center.If you control the central squares(d4,d5,e4,e5) then you have more pressure than your opponent and can infiltrate his/her camp.Control of the center is important because any pieces or pawns in e4,e5,d4,d5 can restrict your opponent's moves very much.

# Answer
> 1 votes
In a nutshell, castling is good but it's peanuts compared to being up a piece. White isn't going to play Bxf7+ no matter what you do, so do something more useful with your move instead.

---
Tags: analysis, strategy
---


title: Ruy Lopez exchange variable

text:
# Question
Title: Ruy Lopez exchange variable
In the exchange variation of Ruy Lopez, why doesn't black capture using the B-pawn? As per good strategy shouldn't we capture towards the center of the board?

# Answer
> 0 votes
there are a handful of reasons why dc6 gives black better chances than bc6:

1. the d pawn is blocking black's c8 bishop so its transfer to c6 opens the diagonal for our bishop's development and also opens space for our queen
2. bc6 leaves black with a weak isolated pawn on a6 which can be fatal in the endgame bc6 is not a horrible move but dc6 is much more precise according to the theory

---
Tags: opening, pawn-structure, ruy-lopez
---


title: Opeing trainer similar to Chesstempo?

text:
# Question
Title: Opeing trainer similar to Chesstempo?
Is there a similar web site that teaches Openings like Chesstempo.com in a sense that you can train and verify lines, etc. I find the Chesstempo user interface confusing and overal user experience isn't satisfactory, so I'm looking for alternatives.

# Answer
> 1 votes
Maybe not exactly in the same direction, I like the courses of Chessable, they allow to train openings by repetition, and I find the tool very intuitive to use. They have quite a few free courses. Check it out: https://www.chessable.com/

---
Tags: training
---


# Question
Title: Could castling ever be proven to be legally allowed for sure if the first move is required to be a pawn move?
In retrograde analysis problems, castling is assumed to be allowed unless it could be proven that either the king or the rook has previously moved.

It is well known, of course, that one could never be sure whether castling is allowed if the king and the rook cannot be shown to have previously moved, since one could simply start the game with silly moves of the knights and rooks for the sake of disabling castling.

Namely, one could just do the following silly moves of the knights and rooks for the sake of disabling castling on both sides (do only the first four moves to only disable kingside castling, or only the last four to only disable queenside castling):

1. Nf3 (or Nh3) Nf6 (or Nh6)
2. Rg1 Rg8
3. Rh1 Rh8
4. Ng1 Ng8
5. Na3 (or Nc3) Na6 (or Nc6)
6. Rb1 Rb8
7. Ra1 Ra8
8. Nb1 Nb8

Now, suppose that one requires the first move by each player to be a pawn move, implying that the initial configuration of the pieces could never be repeated regardless of castling rights.

Then, with that opening requirement, could castling ever be proven to be legally allowed for sure?

I think that the answer is still no even if the first move by each player is required to be a pawn move rather than a knight move.

# Answer
> 3 votes
As the commentators already mentioned, a pawn move doesn't suffice. Not even f3, h3, a3, c3 since the castling destruction manouvre can be prepended. Only information about the number of played moves helps.

Not all hope is lost, though. In fairy chess of all kind it might be possible. Actually, semi-orthodox already suffices: Take a Chess960 position where the rooks are locked, e.g. NBRQKRBN.

---
Tags: castling, retrograde-analysis
---


title: Why is Nf6 a blunder here?

text:
# Question
Title: Why is Nf6 a blunder here?
With Nf6, I'm trying to bring my Knight out. If the Bishop takes it, I can take the Bishop with by g7 pawn. Why is this a blunder?

# Answer
> 4 votes
Because after `Bxf6 gxf6` there is `Qxf6`, which wins a pawn, threatens the rook and threatens mate on f7. You can castle, but then the king is exposed by the missing g pawn. Your only other option is `Rf8`.

---
Tags: analysis, strategy, theory, evaluation
---


# Question
Title: why is ...Bg4 not so popular in this Ruy Lopez line?
```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 Bg4

```

in this line of the Berlin variation, 8 ...Bg4 is not popular among chess masters (it has been played at several times including (Short-Karpov,1989) which ended in a victory for Nigel Short.Why isn't this move as strong as in some of the other Lopez lines, and can you give me examples of this move being performed successfully in that lines?

# Answer
I decided to ask Stockfish for some help for this one. After 9. d3 O-O 10. h3 black must either retreat (bd7 and black has allowed white to play h3 with tempo for free (which restricts the knight and bishop) or play bh5, keeping the pin.

Let's see what happens in a few moves:

```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 Bg4 9. d3 O-O 10. h3 Bh5 11. Nbd2 Na5 12. Bc2 c5 13. Nf1 Nc6 14. Ng3

```

and black must play Bg6 or Bxf3 otherwise white will get Nxh5 Nxh5 Nxe5 Nxe5 Qxh5 winning a pawn with a discovered attack on the knight. If black plays Bxf3 Qxf3, white will have the bishop pair and will basically inevitably get Nf5 (if black tries g6, Bg5 is very annoying. If black plays 14 ... Bg6 white will play Nh4 and actually doesn't even take the bishop: it is stronger to just play Nhf5. Also, if black tries any d5 stuff after Nh4, the idea is STILL Nf5; the dominant knight on f5 will force black to give up the bishop pair to keep white at bay in the endgame.

Even though this is just one variation really, the critical idea revolves around the Nd2-f1-g3 route, and if black tries to stop that stuff on the kingside there's always a4 for white. Even if none of this happens, you can argue that the bishop would be better somewhere else after the queen unpins with Nd2.

Hope this helps.
> 3 votes

---
Tags: opening, ruy-lopez
---


# Question
Title: Can Rook pawn still get win when opponent clock run out?
White has Rook pawn and King vs Black king just jumping from corner and back. But the game played on clock and black king clock run out. White avoided threefold and stalemate and moved his king to just let opponents clock run out. Does white get the win even though this is a draw in a game played without a clock?

# Answer
> 3 votes
Yes. The player whose opponent's time ran out wins if there exists a way to win. A draw only happens, when White couldn't even win with help from his opponent, e.g. when there is insufficient material.

Law 6.9 of the FIDE Laws of Chess states:

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

However, it is not allowed to win such positions by only trying to flag the opponent. If a player with less than 2 min on his clock notices his opponent is only trying to flag, according to article 10.2 a)

> If the arbiter agrees the opponent is making no effort to win the game by normal means, or that it is not possible to win by normal means, then he shall declare the game drawn. Otherwise he shall postpone his decision or reject the claim.

---
Tags: rules, draw
---


title: French or Caro Kann?

text:
# Question
Title: French or Caro Kann?
I find the French more aggressive, as black gets easy queenside play with pieces and generally a pawn avalanche. However, my friend debates that the Caro is better than the French because the Caro allows a queenside expansion as well, but "you get to play with all your pieces" (referring, of course, to the bad light squared bishop in the French).

We both realize that the French bishop can be traded off in many lines with maneuvers like b6, Ba6, where either white trades the bishop, or has a difficult time castling kingside/coordinating kingside pieces. But it's not always possible, and even avid French players will admit that it's difficult to activate the slacker on c8.

What would be a good way to counter my friend's argument? Are there any other arguments (from an objective perspective, preferably) to support playing the French or the Caro Kann?

# Answer
> 14 votes
I can think of a couple counter arguments against what your friend says:

1) Sure in the Caro-Kann you can easily develop your Bishop outside the pawn chain, but there are several variations where the Bishop ends up being a target when developed to f5. The most prominent example is in the advance Caro-Kann:

```
[fen ""]
1. e4 c6 2. d4 d5 3. e5 Bf5 4. Nc3 e6 5. g4
```
1. The fact that the pawn is on c6 means the b8 knight is deprived of its best square to pressure the base of the pawn chain on d4. Essentially you are trading your traditional bad bishop for a bad knight. You can't have everything!
2. Because black played c6 first, a further c5 to pressure the center if not well timed is a loss of tempi compared to the french where you play c5 in one go. This means that in a lot of lines, black must do a lot of prep work before he can afford to play c5, meaning there is also less pressure against white's center. This allows white a lot more leeway as to how he wants to organize his forces. Compare this to the french advance where you quickly play moves like c5, Nc6, Qb6 to pressure the center. Those moves certainly aren't possible to play as quickly in the Caro-Kann. Furthermore, if black opens the center too quickly in the Caro-Kann, he may wish his bishop were back inside the pawn chain to guard against annoying checks on the a4-e8 diagonal!

Ultimately, a debate over whether or not the Caro-Kann is better than the French is fruitless. They are both good openings of equal strength, and your choice to play one over the other is a purely stylistic choice.

# Answer
> 5 votes
It comes down to pure taste. I've been playing the Caro for over 20 years now and would never even consider the French, exactly because of this bishop - and because I've played a lot of very nice attacking games against the French with White.

The other reason why I personally dislike the French is White's boring option of 1.e4 e6 2. d4 d5 3.exd5 exd5 4.Bd3 followed by 5.Nf3. (I have to admit I employed this in a few tournament games myself, because a draw was all I needed for my desired overall outcome.) This takes the fun out of any game, at least if Black is a somewhat serious player.

Having said all this, on top I'd like to quote my old coach: "French is an opening for World Champions." What he meant by this is that you must really watch out, because you have to defend against big onrushes in a lot of variations - with a blocked center, the hidden bishop and without "the Black king's best friend" (the knight on f6). It's often a long battle until you can look for advantage on the queenside, because you have to fight for survival on the kingside. Not to my liking, but others feel differently.

# Answer
> 3 votes
## The Caro-Kann defence

Now that there have been a few answers in favour of the French, I'd like to make the case for the Caro-Kann defense, especially at club level. I deliberately do **not make any objective assessments**, including discussions of bad bishops, tempo losses etc. (as this has been discussed before and is fruitless because both openings are objectively sound). Also, I do **not discuss personal preferences**. Rather, I would like to focus on the **practical advantages of playing the Caro-Kann**:

1. The Caro-Kann offers a much wider variety of pawn structures. This is good if you want to have interesting games and if you want to improve your understanding of chess as a whole. Also, you can play the Caro-Kann positionally or more dynamically, depending on your style preference, as there are always good options also for Black leading to very different play (e.g. 4. ..Nf6 instead of 4. ..Bf5 in the classical mainline, 3. ..c5 instead of 3. ..Bf5 in the advance and so on). You can adapt your repertoire and easily play it for a lifetime without ever getting bored.
2. The exchange variation of the Caro-Kann is very interesting for both sides, instead of the ultra-dull French exchange. Especially on the club level, you will face the exchange variations a lot. Black can quickly get the upper hand if White isn't careful in the Caro-Kann Exchange (compare that to the Exchange French!).
3. There are very few forced lines. Necessary opening theory can be heavily condensed. You can spend your time on improving other areas of your game instead of studying concrete opening variations. The Caro-Kann is very solid and often not as sharp as the French defense, therefore you won't likely be crushed in a deadly attack on your king for forgetting concrete theory. Of course, like in any opening, there are a few lines you should know really well. There are not many "tricks" or dangerous Gambits and sidelines against the Caro-Kann but there are plenty against the French. Currently, I have a lot of fun playing the Schlechter variation against French players, who almost never study this line. Even in games against very strong opposition (2200 FIDE Elo+), I have seldom faced its "refutation". One IM even deliberately did **not** play it "in order to avoid my preparation" even though he knew the best line, of course.
4. Very often, plans and ideas are easy to understand and execute in the Caro-Kann (e.g. play against the Panov-IQP or the minority attack in the exchange Carlsbad). Contrast that with statements of even 2700 Elo GMs (e.g. Svidler) that the French defense is a very hard opening to understand! The plans of adding pressure on d4 are nearly identical in the advance variation of both openings.
5. The Caro-Kann is a fantastic weapon to **fight for a win** (especially against lower-rated opposition) due to the unbalanced nature of the position. There even is a saying that "the Caro-Kann is the new Sicilian", as there are much fewer forced lines that facilitate the Sicilian becoming "dead-analysed" to a draw. Fewer forced lines mean more opportunities to outplay your opponent. If White only wants a draw, he can simplify the position more easily against the French than the Caro-Kann (e.g. by taking on d5).

All these reasons combined, together with my preference for the noble bishops explain why I would definitely choose the Caro-Kann over the French as a main weapon. My answer is partially based on the arguments given by IM Sielecki in his Chessable course.

Finally, I'd like to conclude with **cold hard evidence** for the higher practical value of the Caro-Kann over the French defense: **statistics**.

**According to the lichess database, 1. ..c6 is the best-performing move out of all four major openings (1. ..e5, 1. ..c5, 1. ..e6, 1. ..c6) on amateur level across all playing strengths and time controls.** Only the Alekhine has a better score for Black among lichess amateurs. If you only consider longer time controls (rapid + classical), **it is Black (!!) who wins more games than White after 1. ..c6**!

On the master level, the Caro-Kann also performs better than the French defense.

I rest my case.

# Answer
> 1 votes
There is, as I see it, one main point to argue for the French defence over Caro-Kann, and that is the advance variation. In the French, the advance variation is a sound line, but not the most challenging one. In the Caro-Kann, however, it is more challenging. The reason for why this is I think can be summed up in the following three points:

* Black's light-squared bishop may become a target outside the pawn chain. While this isn't really a big problem most of the time, it gives white a target on the kingside to accelerate a pawn storm in some instances.
* Black's counterattack against white's center is slower than in the french in the case when white plays the advance variation, since black has already spent a tempo playing ...c6.
* With the bishop outside of the pawn chain, black somewhat weakens the defence of the a4-e8 diagonal. This can have dire consequences if black is careless, since a bishop check from b5 can be deadly if black cannot reply with Bd7.

With this being said, both openings are sound and it comes down to a matter of taste in the end when choosing which one to play. The advance variation is not a refutation to the Caro-Kann by any means, and the Caro-Kann does have some advantages over the French defence in other regards.

# Answer
> 1 votes
I prefer the French to the Caro-kann for three reasons:

1. No tempo is wasted on ...c5
2. Black has active pieces.
3. The engine favours it.

The Caro-kann has some pluses as well.

1. The light-square bishop is developed.
2. Black's position is solid.

# Answer
> 0 votes
The way I convinced myself that it's not by accident that Caro-Kann is statistically doing just as well as its "ugly brother" was to recall how many games I lost due to the absence of the bishop in c8. A caricature game below.

The said bishop also sometimes becomes a vulnerability: even in the main classical line White immediately starts to harass it with g4, h4-h5.

Having the bishop on c8 is in a sense more solid. And its perspectives are not as dim as might seem, with possible usage on a6 on even on c8/d7, supporting f6 (which is much less common in Caro, probably unsurprisingly in this context).

That said, these are concrete openings with concrete lines. I believe there is little point arguing philosophically about the reasons one opening is better: they are both totally legit, equalizing openings, as backed up by concrete lines and variations, rather than vague principles with a very limited scope of application.

```
[fen ""]
1. e4 c6 2. d4 d5 3. e5 c5  4. dxc5 Nc6 5. Nf3 Bg4 6. c3 Nxe5? 7. Nxe5 Bxd1 8. Bb5 1- 0
```

# Answer
> 0 votes
See below. This was the quickest objective comparison I saw.

https://www.chessgames.com/perl/chessopening?eco=c00

> French Defense-Number of games in database: 7477; Years covered: 1819 to 2023; Overall record: White wins 40.2%, Black wins 34.0%, Draws 25.8%

https://www.chessgames.com/perl/chessopening?eco=b10

> Caro-Kann Defense-Number of games in database: 7807; Years covered: 1856 to 2023; Overall record: White wins 40.1%, Black wins 27.3%, Draws 32.6%

---
Tags: french-defense, caro-kann
---


title: Output A List of final positions

text:
# Question
Title: Output A List of final positions
I have a .pgn database. I like to extract all of the final positions into a new pgn database. I do not have ay programming skills. What is the best way to do this?

# Answer
You can use my free pgn-extract program with the `-F` flag to output the final position as a FEN string in a comment at the end of the game. If you don't want to include the moves then `--dropply -1` will omit all but the final move of the game in the output. For instance:

```
pgn-extract -F --dropafter -1 games.pgn

```

> \[Event "Milwaukee Northwestern"\] \[Site "?"\] \[Date "1957"\] \[Round "?"\] \[White "Fischer, Robert J."\] \[Black "Kampars, N."\] \[Result "1/2-1/2"\] \[SetUp "1"\] \[FEN "8/pp4p1/3nk2p/2p2p2/5P2/2P1K1PP/PP2B3/8 w - - 2 37"\]
>
> 37. Bd3 { "8/pp4p1/3nk2p/2p2p2/5P2/2PBK1PP/PP6/8 b - - 3 37" } 1/2-1/2
> 2 votes

---
Tags: endgame
---


title: What are the rules of Quantum Chess?

text:
# Question
Title: What are the rules of Quantum Chess?
The game Quantum Chess, as seen in the video where Paul Rudd defeats Hawking, has no "set of rules" written down. You either have to do the in-game tutorial, watch a video on the game and pick them up.

**So what are the rules of Quantum Chess?**

This refers to the game (currently only available on steam) created by Chris Cantwell.

# Answer
> 25 votes
**The board and pieces**

* Quantum chess is played on a regular 8x8 chess board with standard pieces.
* Pieces have rings around them, filled in with colour. These rings show the probability that the piece is in that square.

**Modifications to existing chess rules**

* A player is not required to move their king out of check and the game concludes when there is a 100% probability that one of the kings has been taken. As a result there is no checkmate.
* All promotions result in a queen as of 10/8/17, since underpromoting has not been implemented into the game.

**Movement**

* All pieces move as usual in normal circumstances.
* On any given turn, the player can make one quantum move instead of a normal move.

**Quantum moves**

* Quantum moves are notated with the ^ symbol. (e.g: N^d4)
* When quantum moving a piece, it can make up to two normal moves.
* The probability of the piece moving is equal to the probability that the piece has not moved, resulting in a superposition of multiple board states.
* A quantum move cannot be used to take a piece.
* Pawns cannot make quantum moves.

**Superposition**

* When any quantum move is made, that piece exists in multiple places simultaneously. This is represented by multiple copies of the piece displayed, with appropriate meters to show the probability of finding the piece in that square. There is only one piece, but it can exist in one of multiple places.
* If a piece "takes" one of the copies of another piece in superposition and has 100% probability of being available to take it, the piece is taken if it was in that square. Since there is a probability of the piece being in other squares, those copies of the piece remain, however there is now a chance that the piece has already been taken and is no longer on the board.

* If a piece "takes" one of the copies of another piece in superposition and it is not certain that the piece was available to take it, a measurement occurs. A measured piece will collapse onto one square using a random selection. The probability of it collapsing onto a particular square is the same as the probability that is was moved there. All pieces that are entangled with the measured piece will also be measured and may have their outcome influenced by the measurement of the piece(s) that they are entangled with.

* A pawn can be put into superposition if it takes a piece which is in superposition. If the piece was there, the pawn could take it. If not, moving diagonally was an illegal move. The probability of the pawn being on the new square is the same as the probability that a piece was there to be taken.

* A pawn can also be superimposed by moving two spaces forward, through a square which may contain a piece. This results in entanglement.

**Entanglement**

* Entanglement occurs when a piece attempts to move through an instance of a piece in superposition. The probability of the moved piece existing in its new square is the same as the probability that the obstruction was not there to block it.
* If a piece is entangled with another piece and is measured, both pieces are affected by the results of the measurement accordingly.

---

**Special circumstances**

The following "rules" are combinations of rules from above, however they are worth mentioning as useful tactics:

---

**Quantum Trading**

* It is possible to trade probabilities of pieces, leading to complex trading. For example, it is possible to trade knights in a way which leaves one player with a 2/3 chance of having a knight, and the other with a 1/3 chance of having a knight. The first player is more likely to have benefited from this trade, however it is uncertain until measured.

**Schrödinger's King**

* If the king is in superposition and one of the instances is taken, the probability that that player has lost is equal to the probability that the king was in that square. Since it is not certain that they have lost, play continues.
* This means that it is possible for a player to win a game with a probability that they have already lost by fully capturing the opposing king.

**Ghost capture**

* This is a result of a pawn taking a piece in superposition. If there is one other state of the taken piece still on the board and a piece attacking it, ghost capture can take place. If the attacking piece must move through the square where the pawn would be if it hadn't moved in order to attack the superimposed piece, two outcomes can occur:
    1. The measurement confirms that the piece had not moved, so an attack is impossible and the opposing player gains "half a piece".
    2. The measurement shows that the piece has moved and has already been taken, so the opposing player loses "half a piece".

**Quantum Castling**

* If there is a probability that a piece is between the king and rook, the probability of castling is equal to the probability that the piece was not there. A measurement may take place if two pieces end up on the same square.
* If there is a probability that the rook may have moved, castling can occur with the probability that the rook is available to castle. The king and rook are now entangled since the castling move depends on whether the rook was on the correct square.

**Double Castling**

* After a quantum castle, the king can castle the other way if the rook is available, with the probability of castling being the probability that the king is there.
    + In this example, both sides have castled both ways:

# Answer
> 4 votes
Here's a shorter answer than Aric's, based on my reading of Chris Cantwell's blog post "Quantum Chess" (February 2016). That post ends: "In the next post I’ll go into entanglement and a bit more on the quantum move!" But it seems that the author never actually came back to write any followup posts (possibly because there's not much more to say about the game ;)).

TLDR, I'm not aware of any "quantum" aspects to the game. It's more like "5D Chess with Multiverse Time Travel," except without the time-travel part. Here's the rules:

The game state consists of an arbitrarily large collection of ordinary chess positions. It may help to think of this collection of boards as shares of stock in a company. Each time you make a move, you can either:

* **Make an ordinary chess move.** This modifies every active board in parallel. On boards where the chosen move is legal, the move happens. On boards where the chosen move would be illegal, impossible, or nonsensical, *nothing happens* — it's as if you said "pass" on those boards. ("Pass" is not legal in ordinary chess, but in this case, it's what happens.) On boards where the chosen move captures the opposing king, the board is deleted from the collection. (See *What about check?* below.)
* **Make a "quantum" chess move.** This performs a "2-for-1 stock split" on the collection of active boards. Each old board gives rise to two new boards: one new board where the move takes place á là "Make an ordinary chess move" above, and one new board where it's as if you'd said "pass."

**What about check?** In short, Quantum Chess does not do "check." Kings are not *forced* to move out of check.

When the collection of active boards becomes empty, the game ends. Whoever made the last move (the move that captured the king on all remaining boards simultaneously) is declared the winner.

## Non-rules, and flattening for display purposes

All the cute names in Aric's answer ("Schrodinger's King," "superposition," "entanglement," "double castling," etc) is just flavor text on top of these basic rules.

The Quantum Chess app displays the current game state by "flattening" the collection of board positions into numerical probabilities, square by square. For example, if on 47% of active boards square d7 is occupied by a black queen, and on the other 53% d7 is empty, then the app will display on d7 a black queen icon surrounded by a colored ring that is 47% full. If it's got a black queen 47% of the time and a white pawn 10% of the time, the app will display both icons together in the space with appropriately colored rings. However, **this is just a display gimmick!** There is no sense in which "both pieces" occupy the space, and they cannot in any way "interact" with each other.

## Some rules questions to which I personally don't know answers

Feel free to leave comments (or even edit this answer directly), and I'll try to keep up.

* **Can you move into check?** Since Quantum Chess doesn't really do "check," does that mean that it's legal to move your king into check — or move another piece that discovers a check on your own king? Or are such moves considered "illegal, impossible, or nonsensical" (to use my own phrase) and therefore count as a "pass"? For example, suppose the play is `1.c3 e5 2.d4 [Bb4]`, where `[Bb4]` indicates a "quantum move." Then the position before `3.c4` is:

There are two boards in the active set: one with the bishop on b4 and one with it still on f8. White normal-moves their pawn to c4. In the board where the bishop is still on f8, this is fine. In the board where the bishop is on b4, this move would leave White in check. Is the game state after this move "pawn 100% at c4," or "pawn 50% at c3 and 50% at c4"?

* **Can you castle through check?** A slight variation on the former question.
* **Are there any equivalents of the 50-move or threefold repetition rules?**
* **What happens if the chosen ordinary move is illegal on all active boards?** For example, suppose the play is `1.[d3] e5 2.Nd2 f6 3.Nc4 d6 4.e3 b5`, where `[d3]` indicates a "quantum move." Then the position before `5.Bxb5` is:

From the "flattened" display representation, you might think that the bishop stands a "25% chance" of making it to b5 for the capture; but in fact the knight and pawn are "entangled" (in Cantwell's terminology) — every active board contains *either* a knight blocking c4 *or* a pawn blocking d3. So, is `Bxb5` simply not-allowed-as-a-move and White must play something else? or is `Bxb5` permitted and considered tantamount to a "pass"?

Is the answer any different if White claims they're making `[Bxb5]` as a *quantum* move?

* **What *exactly* is considered the "same" move on two different boards?** For example, suppose the play is `1.e3 e5 2.[Be2] Nf6 3.Qe2 Nh5`. Then the position before `4.e2xh5` is:

Can White make an ordinary move like "I move my piece on e2 to capture on h5"? Or must White specify exactly *which* piece he's trying to move — e.g. "I move my *queen* from e2 to capture on h5" — and on boards where *that exact piece* isn't on e2, nothing happens?

What if the piece being moved is definitely a knight, but it's not clear *which* knight? What if the move is definitely a capture, but the identity of the captured piece is in question? What if the move is "Queen to h5" but it's not clear whether there's a (capturable) piece on h5 or not? (I.e., is `Qxh5` considered a different move from `Qh5`?)

What if the move is an ordinary `Qxh5`, and there's definitely a black knight at h5, but on some boards there's also a black bishop at g4? On those latter boards, is it as if White said "pass" or is it as if White said `Qxg4`?

What if the move is `e5xf6`, always the same white pawn capturing the same black pawn, but on some boards it's *en passant* and on others it's not?

# Answer
> -1 votes
Its best to discuss using isolated pieces and see how probabilities will get associated. E.g. if a N is on D4. now if it is in Quantum state, it can be on D4 and any of the 8 allowed squares. So each of these squares gets probability of 1/9.

When you move a piece, already a measurement has been made.

Double moves don't make any sense. E.g. if a N is on b1 at original move, and in quantum next turn, it can atmost reach a3, c3, d2. it can't reach d5. That would be illegal in chess, its like making two moves at a time. Next turn, yes, it can be there. So original: N@b1 :-100% Prob 2nd turn :- N@b1,@c3,@a3,@d2 :- 25 % probability each. 3rd turn :- N@b1,a3,b5,c3,d5,e4,e2,b3,c4,f3,f1 with equal probability. one has to consider possibility that it went to c3 and returned to b1 also.

---
Tags: rules, chess-variants
---


# Question
Title: Which openings have a 0-0-0 long castle as white and as black?
Long castling is not very common. Are there any statistics as to how many games have long castle? And how many of them are won?

Which openings can one typically play where there is a long castle, as white and as black? Of course the Dragon has white's long castle.

# Answer
By decreasing popularity :

**Main line Caro-Kann**

I believe this is the most played opening with both sides castling long.

```
[fen ""]
1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Bf5 5. Ng3 Bg6 6. h4 h6 7. h5 Bh7 8. Bd3 Bxd3 9. Qxd3 Nd7 10. Nf3 e6 11. Bf4 Qa5 12. Bd2 Qc7 13. O-O-O Ngf6 14. Kb1 O-O-O
```

Various move orders and sub-variations are possible.

**Petroff defense, Nimzowitch variation**

To avoid facing an attack on the kingside, Black more and more often castles long in the 5.Nc3 Petroff.

```
[fen ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3 Nxc3 6. dxc3 Be7 7. Be3 Nc6 {7...O-O was the main line} 8. Qd2 Be6 9. O-O-O Qd7 10. Kb1 O-O-O
```

You can find games of Caruana, Nepomniachtchi, Karjakin or Vachier-Lagrave in this line.

**French, Burn Variation**

An interesting line is the Burn Variation of the classical French:

```
[fen ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 dxe4 5. Nxe4 Be7 6. Bxf6 gxf6 7. Nf3 b6 8. Bd3 Bb7 9. Qe2 Nd7 10. O-O-O c6 11. Kb1 Qc7 12. c4 O-O-O
```

This line is sometimes associated with Morozevich.

**Ruy Lopez, Exchange variation**

In the Exchange Ruy Lopez with 5.d4, Black most often castle short but long castle is also seen quite regularly :

```
[fen ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Bxc6 dxc6 5. d4 exd4 6. Qxd4 Qxd4 7. Nxd4 Bc5 8. Be3 Nf6 9. f3 Bd7 {9...O-O is the main line} 10. Nd2 O-O-O 11. O-O-O
```

This also happens with 10.Nc3 instead of 10.Nd2.

**Others**

I think there are also some lines in the Sicilian with b3, but I have to check how often they are played. @cmgchess correctly mentionned some classical sicilians in comments. And there must be a few other opening lines with double long castle, which don't come to mind right now.
> 8 votes

---
Tags: opening, strategy, castling
---


title: How is Stockfish so fast?

text:
# Question
Title: How is Stockfish so fast?
I'm currently developing a bitboard-based chess engine for fun and can generate around 5.5 million positions per second on perft tests. I ran the same tests on Stockfish, which can do around 130 million positions per second. What is it that makes Stockfish (and other engines) so much faster?

# Answer
There are a number of reasons. The Main one is its aggressive **Alpha Beta pruning** and **late move reductions**.

To explain a bit further. **AB Pruning** is a search algorithm which basically cuts out the number of nodes in its search tree. How it works is it stops evaluating when it determines and proves the move to be worse than another examined moves.

**Late move reduction** is a slightly harder concept but it again searches the "tree" more efficiently. It does this by effectively diving down a "algorithmically" more probably tree.

If I remember the release paper correctly the elo for Stockfish 14 is 3350 +/-5% and that was based off a 4 threaded CPU.

In short there are the implementation of mathematically proven formulae to do with pruning infinite possibilities to the most correct, whilst also searching deeper down the most probably correct line.
> 1 votes

# Answer
Perft speed can be affected by:

* Coding language - for example, compiled vs interpreted.
* Bulk counting - whether you un-make leaf nodes - I believe SF doesn't do this, which makes it significantly faster.
* How your move generator works - for example, whether it performs legality checks on the generated moves.
* Whether you're using CPU or GPU for move generation.
* CPU speed/frequency.
* CPU multi-processing - for example, whether your perft is single-threaded or multi-threaded.
* CPU cache size.
* Which position you're using for perft.

Without knowing these variables, it's hard to say whether your perft numbers are reasonable or not.

As an example, my single-threaded C# magic bitboard code does perft from the standard starting position at around 100 million nodes per second on a single core of a Ryzen 5950X processor.
> 1 votes

# Answer
5.5 million moves per seconds is very decent I would say. Enough to make a 2700 or 2800 rating engine with a good evaluation function. I made a bot without any bitboard and got to around 2.5-3.5 knps and managed to beat 2300-2400 bots on chess.com with a mediocre evaluation function. 130 million positions per second is 100% for multi threading bots. No way you can achieve that with only one core. I knew an a version of minmax with multithreading but I don't really suggest implementing it since it quite hard to get it right.
> 0 votes

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


# Question
Title: Why is 11...Qg6 the best move in this line of the italian?
In the following position:

```
2kr3r/ppp1bppp/2nq4/1N2pb2/8/3PBN2/PPP2PPP/R2Q1RK1 b - - 4 11

```

The engine (Stockfish 14) suggests 11...Qg6 as the best move for black. It evaluates 11...Qg6 -3.4 compared to 11...Qd5 -2.1 which is second. That's some difference, but the most puzzling thing for me is that 11...Qg6 was chosen in ~70% of the (few) games in the Lichess.org database for players over 1800.

In g6 the queen is in front of the king, but it will have to move after Nxe5 and at this point there is not realistic to thing of an attack against the king of something like ...Bh3. So, what is so obvious about 11...Qg6 here?

# Answer
> 2 votes
The queen is well placed on g6 facing the White king and hitting the weakest point of the castle, g2.

You were afraid of 12.Nxe5? but this pawn is protected by the Nc6, so no, the Black queen doesn't have to run away. Also 12.Nh4? is no problem: 12...Bxh4.

You mentionned 12.Nxa7? in a comment but this should not bother Black, who is winning after 12...Nxa7 13.Bxa7 and now either:

* 13...b6 trapping and soon winning the bishop.
* 13...Bh3 threatening mate, e.g. 14.g3 Bxf1 or 14.Ne1 b6 (14...c5 is also good) followed by 15...Kb7-+
* 13...e4 that you mentionned, when 14.Ne5 hits the queen but 14...Qf6 counterattacks on the knight and White is too uncoordinated to save all their pieces.

---
Tags: engines, strategy, queens, italian-game
---


title: Problem with tablebases

text:
# Question
Title: Problem with tablebases
I hope this is the right forum for my question.

So, I have all 5 men files on my HDD and the two files

KRPPvKR.rtbz

KRPPvKR.rtbw

In the position here (8/2K2k2/3R3P/5P2/8/8/8/r7 w - - 0 10) everything looks good.

Image 1

But if I play the move 10.h7, Angie starts calculating. Stockfisch is right, 10... Kg7 is a draw, but something is wrong.

Does anyone have an idea why the engine starts calculating here?

picture 2

# Answer
If you only have those files then the engine needs to calculate positions that are not in the files. In your case I expect it is calculating the effects of pawn promotion which would need to understand positions with a queen, bishop, knight, or additional rook.
> 2 votes

---
Tags: engines, tablebases
---


# Question
Title: Is it okay to use Scholars mate against strong players?
I am comfortable using scholars mate opening in my game. If it does not work then I can always transform it into a good offense/defense.

# Answer
> 25 votes
Of course, you can play whatever you want against strong players. You won't checkmate them with Scholar's Mate, and you won't get an opening advantage either, but once you're at the board there's no rule that says you can't play inferior moves.

Kramnik allegedly once intended to try it on Kasparov:

> Vladimir Kramnik is not a beginner at all, but nevertheless some years ago he intended to try out the move 2. Qh5 against Kasparov in the PCA Grand Prix rapid tournaments, though only in the blitz games that were to decide the outcome when rapid games failed to do so. Kramnik told this to Nigel Short, who recently told it to us in his column in the Sunday Telegraph ... But it would have been a responsible experiment. Imagine the shock when the world champion would be threatened with a Scholar's Mate, not by someone like Harrison or Becker, but by one of his most respected colleagues. The cheek of it! It would appear as a real insult.
>
> As an added advantage Kasparov would be out of his much-feared opening preparation from move two. And, most important, in the main variation after 1. e2-e4 e7-e5 2. Qd1-h5 Nb8-c6 3. Bf1-c4 g7-g6 4. Qh5-f3 Ng8-f6 5. Ng1-e2 (instead of Jake's 5. Qb3?) White is not worse, according to Kramnik. True, he doesn't have an advantage either, as Short sensibly remarks, but one can't have everything.

I suppose the main consequence of note would be that the opponent might laugh or feel insulted (two diametrically different responses!). It's very possible, but when strong players are okay with playing the Bongcloud occasionally, playing for Scholar's Mate is tame by comparison.

# Answer
> 11 votes
I guess you are asking if the strong players would feel insulted? Speaking for myself, I would chuckle and start planning how to punish you. If you are fortunate enough to be paired with a strong opponent, just play your best and prepare to learn as much as you can. If you only learn that Scholars Mate is a bad idea, well, you knew that already

# Answer
> 5 votes
Not only is it OK but strong players also play this opening. Most famous is probably Nakamura. It is characterised by the moves

```
[fen ""]

1. e4 e5 2. Qh5

```

with the idea of following up with Bc4 if black allows.

The opening has several names: Kentucky Opening, Queen's Attack, Queen's Excursion, Wayward Queen Attack, Patzer Opening, and Parham Attack. I like Wayward Queen Attack.

Serbian IM, Miodrag Perunovic, has produced produced a 2 hour (!) YouTube video investigating the opening.

# Answer
> 2 votes
As a weak player myself (actually weak, not 1900 "weak" :P) I would say that when us plebs play strong players, anything goes. If you can get away with it, try it. Just be prepared for your strong opponent to respond by abandoning all coddling and simply destroying you for your presumptuousness.

I would instead argue that what is not OK is using scholar's mate against weak players, those who have a high chance of falling for it. If you do, then at least immediately offer a rematch and explain how to counter this trivial attack.

I remember back when I was just learning to play chess, I was playing with someone much better than I who mated me with the Scholar's mate. I found it exceedingly rude and an unpleasant experience. He didn't offer to replay, he just gloated. Which was absurd since he was clearly the better player and had nothing to prove by beating me.

So that, using silly tricks against far weaker opponents, I consider bad sportsmanship. Using them against stronger opponents, however, is fair play and they should know better than to fall for them.

# Answer
> 0 votes
Nakamura played all kind of openings for his YT/Twitch channel, all posted in 'opening trash - garbage openings' series.

https://www.youtube.com/watch?v=4GdjCF136Fc

I am not good player by any means (somewhere around 1900 ELO) and from time to time someone would play it against me.

# Answer
> 0 votes
Although one should generally seek to win or at least draw when playing rated games, one should also seek to use the experience to improve one's play. Attempting the Scholar's Mate against someone who will fall for it will be a waste of everyone's time, but attempting 1. e4 e5 2. Qh5 as White against people who won't fall for it may allow one to learn the best ways to respond as Black to people who try that opening, as well as gain judgment as to when moving one's queen out is good and when it is bad.

---
Tags: opening
---


# Question
Title: Every longbow-wielding peasant's finest hour?
It's called the English opening - some reference to Howard Staunton and the perambulations of the mid to late 19th Century; but, does the variant name refer to the Ancien Regime charging up a muddy hill, or the propensity to loose masses of arrows then get stuck in with the sword and shield after?

```
[Title "English Opening: Agincourt Defense"]
[fen ""]
[Event "Rated Bullet game"]
[Site "https://lichess.org/AeUmXNuE"]
[Date "2023.09.15"]
[White "heallan"]
[Black "bsalman"]
[Result "1-0"]
[UTCDate "2023.09.15"]
[UTCTime "00:22:41"]
[WhiteElo "1381"]
[BlackElo "1446"]
[WhiteRatingDiff "+6"]
[BlackRatingDiff "-6"]
[Variant "Standard"]
[TimeControl "120+0"]
[ECO "A13"]
[Opening "English Opening: Agincourt Defense"]
[Termination "Normal"]

1. Nf3 e6 2. c4 d5 3. cxd5 exd5 4. d4 Be6 5. Nbd2 Bb4 6. a3 Bxd2+ 7. Bxd2 Nf6 8. e3 Ne4 9. Ne5 Nxd2 10. Qxd2 O-O 11. Bd3 Nc6 12. Nxc6 bxc6 13. Qe2 g6 14. Qf3 Qd7 15. Rc1 Bf5 16. Bxf5 Qxf5 17. Qxf5 gxf5 18. O-O Kh8 19. Rxc6 Rac8 20. b4 Rg8 21. Rfc1 Rg7 22. Rxc7 Rcg8 23. g3 h5 24. Rxa7 h4 25. Rcc7 hxg3 26. fxg3 Re8 27. Rxf7 Rxf7 28. Rxf7 Rxe3 29. Rf8+ Kg7 30. Rxf5 Rxa3 31. Rxd5 Ra4 32. Rb5 Kf7 33. d5 Ke7 34. Rb6 Kd7 35. d6 Ra1+ 36. Kg2 Ra2+ 37. Kh3 Rd2 38. Rb7+ Kxd6 39. Rb6+ Kc7 40. Rb5 Kc6 41. Rg5 Rd4 42. Rg4 Rd5 43. Rg6+ Kb5 44. Rg4 Rh5+ 45. Kg2 Rf5 46. h4 Rh5 47. Rg5+ Rxg5 48. hxg5 Kxb4 49. g6 Kc5 50. g7 Kd6 51. g8=Q Ke7 52. Qg4 Kf6 53. Qf4+ Ke6 54. g4 Kd5 55. g5 Ke6 56. g6 Ke7 57. g7 Ke6 58. g8=Q+ Kd7 59. Qf6 Kc7 60. Qgg7+ Kc8 61. Qff8# 1-0

```

So, why is this response to the English Opening called the Agincourt Defense?

2k2Q2/6Q1/8/8/8/8/6K1/8 b - - 6 61

# Answer
> does the variant name refer to the Dukes of Burgundy charging up a muddy hill, or the propensity to loose masses of arrows then get stuck in with the sword and shield after?

Alas, no. It is more prosaic. At Agincourt the French faced the English and here white plays c4, the English, and black responds with e6 and d5, the French. So, we have the French against the English.
> 5 votes

---
Tags: opening, english-opening
---


# Question
Title: Is there a recourse when a player does not resign in a clearly lost position?
I manage a chess club. Two 1900+ players A and B were playing. They reached a position where A had K+Q, and B had only K. They each had about an hour left on their clocks. B just waited the full hour, letting his flag fall instead of resigning, causing A to miss his last bus home.

B knew the situation. He was hoping A would choose his bus home over the win, and offer a draw or even resign in order to catch the bus. He admitted this.

What recourse, if any, is there? According to the laws of chess, what B did is entirely legal as far as I know. But it is extremely unsportsmanlike.

A is extremely angry (I can understand why) and I wish there were something we could do...

# Answer
From your question, it seems that the governing laws would be FIDE’s rather than USCF’s.

This being so, who takes the role of arbiter in your events? Under FIDE Laws the arbiter has the discretion to adjudicate this absurd situation:

> Preface 0.2
>
> The Laws of Chess cannot cover all possible situations that may arise during a game, nor can they regulate all administrative questions. Where cases are not precisely regulated by an Article of the Laws, it should be possible to reach a correct decision by studying analogous situations which are regulated in the Laws.
>
> The Laws assume that arbiters have the necessary competence, sound judgement and absolute objectivity. Too detailed a rule might deprive the arbiter of his/her freedom of judgement and thus prevent him/her from finding a solution to a problem dictated by fairness, logic and special factors. FIDE appeals to all chess players and federations to accept this view. The Laws of Chess cannot cover all possible situations that may arise

A relevant law is:

> Article 11: The Conduct of the Players The players shall take no action that will bring the game of chess into disrepute.
> 21 votes

# Answer
If you are using USCF rules, rule 18G says the director may adjudicate a game in an emergency situation. And they can declare an emergency situation if:

> a player with substantial time remaining and a poor position disappears for more than 15 minutes or is present but shows little interest in considering the position. Such behavior is unsportsmanlike and the director is encouraged to adjudicate, possibly after a warning.
> 44 votes

# Answer
> What recourse, if any, is there? According to the laws of chess, what B did is entirely legal as far as I know. But it is extremely unsportsmanlike.

You are right. The laws give you no recourse in this case.

However, since you manage the chess club and are, presumably, the tournament organiser for the club's competitions, you could explain to the player that his behaviour is inexcusable. You could then tell him that if there is any repeat of such behaviour then he will be immediately ejected from the tournament and banned from future club competitions. This should concentrate his mind.

If you feel the need for more extreme action (and you know far more about the situation than we do) then you could return the player's entry fee and exclude him from the rest of the competition.
> 15 votes

# Answer
Player A started playing a chess game that would cause him to miss his last bus home if both players used their time. Even if he himself still had an hour left! That's on him, it's a risk he took himself. It's even a tiny bit unsportsmanlike to miss a bus because a game takes its normal time and then complain about it, isn't it?

The FIDE laws themselves don't really have a way to deal with a player just using their allotted time. I don't think the Preface should be used. It's expected that the game takes this long.

**However** what changes it for me is that a) player B knew about the bus situation, b) his behaviour was only because of that, and c) he even admitted it. That is of course extremely unsportsmanlike behaviour.

*The chess club* can choose not to let player B enter their competitions anymore, or give them a warning that that will happen next time, or whatever. You don't want such players in your tournament.

And it should be explained to A that games will sometimes take this long, and he should plan accordingly.

Final thing to mention: if A had resigned, the result would still have been a draw (under current FIDE rules), as B had no way to win on the board anymore. So "offer a draw or even resign" would have been the same thing. There would have been no need to offer a draw, A could just have declared it a draw.
> 10 votes

---
Tags: etiquette, resigning
---


# Question
Title: Reasonable engines to test against (Not StockFish)
I've built a chess engine in Python which I've been testing against StockFish through the use of the Python-Chess package.

Testing against StockFish seems/is problematic, and as a result I'm looking for suggestions of engines to test against.

There are two major issues with testing against StockFish (the first much more significant than the next)

1. StockFish is partially used in generating the training data for the engine's evaluation function.
2. StockFish is extremely good, and even given extremely little time will perform well. This makes it difficult to see the changes in the engine's strategy which resulted from a change in the engine's code

The engines I'm hoping to play against need to have no serious bugs or problems, and ideally would play at levels similar or a bit below a human master, without spending too much time running them. UCI engines are prefered so that my engine can easily communicate with them through the Python-Chess API (note that this doesn't mean my engine supports UCI).

If it helps anyone to have some context, my engine is Batch First.

# Answer
Since your engine supports UCI, I would suggest checking out lichess.org. You can make a BOT account there and test against several other BOTs and people as well! Also, you can get your BOT rated in different time formats!!

I must warn you that most of the BOTs on lichess are some version of StockFish or other strong engines but you can find ample other BOTs.

Among strong BOTs (apart from Stockfish ones), I would suggest checking out:

1. LeelaChess: A neural net based BOT.
2. ASMFish

There are many more BOTs on lichess, you can view them here on lichess BOT team.

You can also find many not so strong self-implemented engines that you might like testing against, for example this.
> 8 votes

# Answer
http://computer-chess.org/doku.php?id=computer\_chess:wiki:lists:chess\_engine\_list

* Arasan
* GreKo
* Crafty
* Rodent
* Toga etc
> 3 votes

# Answer
To complement the list given by @SmallChess, you can find at https://www.computerchess.org.uk/ccrl/4040/ an ELO ranking of many chess engines.

In the 2300-2600 range ("similar or a bit below a human master"), and amongst open-source engines, you have :

* K2 0.87 (2580 ELO)
* Jazz 840 64-bit 4CPU (2552 ELO)
* Maverick 1.5 64-bit (2522 ELO)
* Winter 0.1.1 64-bit (2492 ELO)
* Lozza 1.18 64-bit (2452 ELO)
* Topple 0.1.1 64-bit (2360 ELO)

I haven't tested these engines myself, but they seem to fit your criterias.

**Update** : If you're looking more for engines in the 2000-2300 range, then these engines might suit you better :

* Absolute Zero 2.4.7.2 64-bit (ELO 2294)
* CT800 1.30 64-bit (ELO 2253)
* Zevra 1.8.4 r650 64-bit (ELO 2236)
* ZCT 0.3.2451 (ELO 2210)
* Tunguska 1.0 64-bit (ELO 2133)
* Cinnamon 2.0 64-bit (ELO 2054)
> 2 votes

# Answer
Try https://github.com/fernandotenorio/Tunguska And let me know if your Python engine beat mine! =D
> 1 votes

# Answer
> StockFish is extremely good, and even given extremely little time will perform well. This makes it difficult to see the changes in the engine's strategy which resulted from a change in the engine's code

You can use `go depth x` or `go nodes y` to get Stockfish to almost arbitrary strength levels.
> 1 votes

# Answer
> StockFish is extremely good, and even given extremely little time will perform well. This makes it difficult to see the changes in the engine's strategy which resulted from a change in the engine's code

Aside from the mentioned UCI depth option, Stockfish also supports different playing strengths. See Is there a list of approximate Elo ratings for each Stockfish level? for discussion on Elo.
> 0 votes

# Answer
Here are a two suggestions:

1. Micromax
2. Sunfish
> 0 votes

# Answer
Here is a list of computer chess engine rankings. Elo's are provided.

http://www.computerchess.org.uk/ccrl/4040/
> -1 votes

---
Tags: engines, stockfish, uci
---


title: I am only good in bullet. Why?

text:
# Question
Title: I am only good in bullet. Why?
I am 2100 in lichess bullet (1+0) and 1500-1700 to anything else. Why does it happen?

# Answer
> 2 votes
If you play mostly bullet you will be better at bullet. Bullet restricts the depth of thinking to a very small amount of time which means its easier for one to make a mistake for the opponent to capitalize on. Increase the time length that someone can make their plans their position becomes harder to capitalize on.

Article if your interested in a GM's perspective. https://chessmood.com/blog/does-bullet-chess-make-you-better

---
Tags: lichess, bullet-chess
---


# Question
Title: Why is d5 better than dxe5 in this position?
I tried looking at a few lines with the engine but still couldn't quite understand how white managed to obtain a better position in some of the lines. Any help would be greatly appreciated.

```
[Title "White to move"]
[fen "r1bqr1k1/1pp2pp1/p1n2n1p/4p3/3PP3/2PB1N1P/P2Q1PPB/R4RK1 w - - 0 15"]

```

# Answer
After 1.dxe5 Nd7 Black will get back their pawn with ...Nxe5 and be relieved that White's impressive center has been torn apart.

After 1.d5! The Nc6 is sent to a bad square and leaves the Pe5 with insufficient defense, e.g. 1...Ne7 2.Nxe5 with a décisive advantage for White.
> 2 votes

---
Tags: strategy
---


# Question
Title: Can black win (or even draw) after 3. Qxf7 Kxf7?
Recently I've been watching a streamer who plays chess. He's been using an aggressive opening with 3. Qxf7 (when he's white). The opponent is forced to respond with Kxf7. And the streamer always wins even against strong masters so I think the position is strongly winning for white.

For an exmaple game, consider 1. e4 e5 2. Qh5 kf6 3. Qxf7 Kxf7.

Yes white is down a queen, but look at the compensation. Black is down a critical e pawn leaving a big hole in the middle. Black is forced to bongcloud and loses castling rights. Black is down a tempo or more, having to move the king to safety, allowing white to develop faster. And finally, black is in an unfamiliar position and taken by surprise (unless this opener catches on).

Is there anything black can do to stabilize and win, or if that's not possible, draw in this position?

# Answer
```
[FEN ""]
1.e4 e5 2.Qh5 Nf6 3.Qxf7 Kxf7

```

According to the lichess player database, White wins about 31% of the time, while Black wins 65% of the time. While this would indicate that White has *some* compensation for the queen, it's clearly not enough. Black is going to waste some time on their king safety, true, but White is actually *down* a tempo to start out, as Black's knight is developed but White has nothing developed. This makes it much harder to capitalize on the king exposure. The immediate 4.Bc4+ attempting to develop with tempo is countered by 4...d5.

Black's plan here is to survive and get to a more defensible position - having sacrificed a whole queen, White has no chance if they can't get to Black's king fast. If Black can develop the f8 bishop and get in Rf8 and Kg8, Black's as good as castled (and the half-open f-file can actually help Black's rook.) Playing d6 and Be6 can help guard the diagonal the king is on (and the d6 pawn guards e5.) Any piece trades are probably in Black's favor, as White can't afford to go to an endgame.
> 1 votes

# Answer
White is clearly and totally lost after 1. e4 e5 2. Qh5? Nf6 3. Qxf7??. The statistics in the lichess database cited by DM above are very surprising in light of that fact (I would have expected a black winrate in the high 90 percent range, not in the range of just shy of 70 percent; LC0 is less generous than me, giving Black a winning probability of 99.9 percent).

However, looking at the actual games in the lichess database that end with a white win, it is worth noting that they seem to come from White players with lichess ratings \< 1700 playing bullet. At that level, in bullet, I suppose a lot goes, especially if one side is very familiar with an opening the other side rightly thinks is totally losing.

A much darker, also possible explanation is that these are players who are substantially stronger than their rating and who use this opening as a kind of handicap to sandbag much weaker opponents.

In any case, there are no redeeming factors to this opening and Black is totally winning here, with no compensation for White to speak of.
> 4 votes

---
Tags: opening, queen-sacrifice
---


# Question
Title: What are some good chess resources to learn from?
I have looked in a lot of places, but I can't find good places to learn chess. I am at the stage where I know basic chess strategies, but my rating is still below average. I can't find a source longer than a short article to learn from. Do you have any suggestions? I can't really pay for things (my main roadblock, but I can if I have to.

# Answer
I'm an older player (84), but in my youth I read several chess manuals which explained all the basics and gave hints for improvement, such as books by I.A.Horowitz, Fred Reinfeld and Reuben Fine. These are still available on eBay at reasonable prices. And there are certainly more modern books that cover the same area, by Bruce Pandolfini, Jeremy Sillman, and Yasse Seirawan for example. But now in the era of the computer and the Internet, there is a readily available source of this information at your fingertips. Just Google tips for chess improvement. GM Arthur Bisguier for instance has written "Ten Tips for Winning Chess" which you can find there. And I'm sure there are countless others. Then there's "YouTube" which has many free chess tutorials and also game analyses, such as by Agadmator and Mato. I watch them there myself. Those are all good starting places. And of course you have to supplement what you learn by applying it in actual play. Good luck on your chess journey!
> 3 votes

# Answer
Remember.. No question is dumb

It really depends which chess learning stage you are.. If you are absolute beginner , either sign up for chess lessons on some popular chess websites. Understand the basics of chess. How to move pieces , rules of chess , Openings , Middle Game and Endgame.

Once you learn all that and become an intermediate player , learn about variations in openings , tactics in Middle Game and How to win Endgames.

I hope these two phases should keep you busy for a relatively long time.

I run a chess channel on youtube however I am not a chess expert and I am also learning just like you. I do share some of the chess content that I study. Feel free to watch those videos. But remember , if you want to learn chess , study books and sign up for a good chess website.

https://www.youtube.com/channel/UCfBrplys3U5FMAHHkbGmhGg
> 2 votes

# Answer
The Practice section on Lichess has some nice interactive lessons. If you like this format, you can also take a look at the top Lichess Studies, which are really good as well.

I also want to mention a few instructive YouTube channels:

There is also Chessable. Since you are unable to spend money, you can take a look at their free courses.

---

Also, there are a lot of great questions on here which include other great resources for learning. Here is a list of some of the best ones:
> 2 votes

# Answer
I'm a beginner-level chess enthusiast and have recently started learning the game. One book I've found incredibly helpful and enjoyable is "Encyclopedic Manual of the Game of Chess" by Mikhail Tal and Nikolai Zhuravlev.
> 0 votes

# Answer
KorpalskiChess.com has a lot of interactive exercises carefully selected by a chess coach.
> 0 votes

---
Tags: beginner, recommendations
---


# Question
Title: Why is this line of the Caro-Kann playable for white?
Today in an online game my opponent opened with e4 and I played the Caro-Kann, as I usually do. We went into a line that was new to me, shown below:

```
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1. e4 c6 2. Nf3 d5 3. d3 dxe4 4. dxe4 Qxd1+ 5. Kxd1

```

I felt pretty good about this position, since white gave up their castling rights for a small advantage in development, which doesn't look worrying at all with the queens already traded off and I went on to win the game. Much to my surprise however, I later discovered that after 5. Kxd1 Stockfish slightly prefers white's position, and that this line has been played by various superGMs with good results.

Why is the position after 5. Kxd1 good for white? What is white's compensation for being unable to castle? What are the main ideas for both sides in this position?

# Answer
> 9 votes
> What is white's compensation for being unable to castle?

With queens off the board castling rights are not that important.

> Why is the position after 5. Kxd1 good for white?

White has a center pawn and a nicely developed knight while black has a pawn on c6 taking away the b knight's best square, no center pawn and no pieces developed. In these open positions fast development is very important.

# Answer
> 3 votes
I have been playing this variation for many years, I think it is excellent for White. It gives a stable advantage and White does not risk anything.

Why is the endgame so good? The short answer is, White will play a4 and if possible a5 at some point and point out the compromised Black structure on the queen side. This might sound surprising but if you play a couple of games you will realize that this is difficult to combat. A typical line might go something like this

```
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1. e4 c6 2. Nf3 d5 3. d3 dxe4 4. dxe4 Qxd1+ 5. Kxd1 Nf6 6. Nbd2 Bg4 7. Be2 Nbd7 8. Ne1 Bxe2+ 9. Kxe2 e6 10. a4

```

and White is already much better. You continue with a5 if you can, the White knight goes to d3 and the other to c4 if allowed. White will play f3 to completely solidify the center and stay with a good Bishop. Usually that Bishop goes to e3 putting pressure on a7 which holds Black's rook back. If Black goes a6 (or a5 immediately here) there's a big weakness on b6. Then White simply puts the rooks on the d file and slowly advances.

The computer even gives the option to play h4 at some point and push on the king side too though I haven't been able to make this work in a human game consistently so I would probably not recommend it.

What can Black do to combat this? To be honest, I don't know. If I were a Caro Kann player I would simply not go into this endgame. With precise play you will hold but it's no fun and the winning chances are near nil. 3...Bg4 can lead to some sharp variations where White plays h3 g4 and Ne5 at some point, following up with h4 and it can become very tactical. If you like a tactical mess you can play that with Black. 3...g6 is more solid and will likely transpose into some hyper accelerated Dragon Sicilian after 4.e5 c5 5.c3 followed by d4 or similar variations. The alternative is 3...Qc7 which fights for the e5 square more directly and "threatens" that e5 move.

---
Tags: opening, caro-kann
---


# Question
Title: g4 pawn push to remove bishop pin - why is it good sometimes? (specific example below)
In the following position, why is g4 so powerful (+4.1 according to stockfish), when g4 is normally considered a weakening move?

```
[Title "Why is g4 so powerful here?"]
[fen ""]
[Startply "28"]

1.e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. d3 d6 6. O-O Be7 7. Be3 b5 8. Bb3 O-O 9. a3 Bg4 10. Nc3 Nd4 11. Bxd4 exd4 12. Nd5 Nxd5 13. Bxd5 Rb8 14. h3 Bh5

```

# Answer
> 4 votes
The first thing to note is that 14...Bh5 is a blunder. Much better would have been 14...Bd7 keeping an eye on the weak light squares on the queenside and particularly c6.

The move 15. g4 is very strong here because it comes with tempo and frees the knight to take the d4 pawn, again with tempo. It is only one pawn but white's pieces are better and white has the initiative. White is calling the shots and black has to respond rather than make their own plans.

Here is some analysis:

```
[Title ""]
[fen ""]
[Startply "28"]

1.e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. d3 d6 6. O-O Be7 7. Be3 b5 8. Bb3 O-O 9. a3 Bg4 10. Nc3 Nd4 11. Bxd4 exd4 12. Nd5 Nxd5 13. Bxd5 Rb8 14. h3 Bh5 (14...Bd7 15. Nxd4 Bf6 16. c3 Bxd4 17. cxd4 c6 18. Ba2 Qf6 {and black is regaining the pawn}) 15. g4 Bg6 16. Nxd4 {threatening the knight fork on c6} Rb6 17. Nc6 {anyway} Qd7 18. Nxe7+ Qxe7 19. a4 {quick, before black has time to play c6} bxa4 20. Rxa4 Qf6 21. b3 c6 22. Bc4

```

# Answer
> 2 votes
Normally moves like h3-g4 are considered weakening because they open up your king, and also provide pawn levers for the opponent. For example after h3-g4, if opponent plays h5, then they can conceivably open lines against your king after ...hxg4.

But in this position:

1. Black is in no shape to attack White's king. If anything it is White who will attack Black's king (they have far more space on the kingside).
2. Dynamic considerations - after ...Bg6, White gets to eat a free pawn on d4 (which simultaneously threatens f4 to roll Black off the board on the kingside).

Point 2 is the more important factor - you can see how the engine evaluation jumped after ...Bh5, since it loses a pawn.

# Answer
> 0 votes
In this case, Black's bishop will be trapped on g6 by White's pawns. f7 is pinned by White's bishop so the only retreat square is h7. That white bishop is rather difficult to kick out so it will take at least three moves for Black to re-manuever his bishop.

---
Tags: pawns, bishops, pins
---


# Question
Title: How do arbiters handle touch move complains where players deny?
So, two cases. Player A (A) and Player B (B)

**Case 1**

B touches a piece. A sees it. B plays something else. A complains to arbiter that B didn't play the touched piece. Arbiter didn't see that B touched the piece.

**Case 2**

B didn't violate any touch move rule. A complains to arbiter that B touched a piece and didn't move

So in case 1 A is telling the truth and B can deny it. In case 2 A is lying.

In these situations whose side does arbiter take? Assuming there are no 3rd party witnesses. How does the arbiter know who is lying and who is telling the truth?

# Answer
> How do arbiters handle touch move complains where players deny?

There is a very simple principle arbiters follow: "Claims must be supported by evidence"

So, for instance, if you claim a draw by 3-fold repetition it is not enough for you to make a claim. You must also provide evidence via your scoresheet for it to be considered.

Hence in both cases the arbiter has no evidence that a piece was touched and will rule that the player on move is free to make any legal move. The incident may give the arbiter reason to watch that board more closely in future.
> 14 votes

---
Tags: rules, fide, etiquette, arbiters
---


title: Timeout vs Insufficient Material

text:
# Question
Title: Timeout vs Insufficient Material
This is not a new topic but it did happen in my game at chess.com. I was playing white and played the only legal move h7 and was checkmated on the next move.

My question is: What will happen if I just let my time ran out? Will the system give a draw as black has only one knight and the system will consider it as "insufficient material" even though there is a checkmate in 1 move?

```
[Title "Timeout vs Insufficient Material"]
[fen "5k1K/8/7P/6n1/8/8/8/8 w - - 0 1"]

1. h7 Nf7#

```

# Answer
> 2 votes
Chess.com specifically uses these rules for a dead position:

> Here are the piece combinations that lead to a draw by insufficient material:
>
> * King vs. king
> * King and bishop vs. king
> * King and knight vs. king
> * King and bishop vs. king and bishop of the same color as the opponent's bishop

Because you have a pawn your position does not meet any of these rules so you would lose.

# Answer
> 1 votes
> What will happen if I just let my time ran out? Will the system give a draw as black has only one knight and the system will consider it as "insufficient material" even though there is a checkmate in 1 move?

If chess.com uses the FIDE Laws of Chess then, of course, it is a win for black. Here is the relevant section:

> 6.9 Except where one of Articles 5.1.1, 5.1.2, 5.2.1, 5.2.2, 5.2.3 applies, if a player does not complete the prescribed number of moves in the allotted time, the game is lost by that player. However, the game is drawn if the position is such that **the opponent cannot checkmate the player’s king by any possible series of legal moves**.

Not only does there exist a possible series of legal moves, that series of legal moves is the *only* legal series of moves.

If chess.com does not use the FIDE Laws of Chess (possible but unlikely, I think) then you need to ask them.

---
Tags: endgame, checkmate, online-chess, draw, knights
---


# Question
Title: What are some decent books for explaining the positional ideas of the 4...Nxd5 line of the QGD from black's perspective?
Specifically, this line.

```
[fen ""]
[Startply "8"]

1.d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 Nxd5

```

# Answer
The line is the subject of Chapter 3 of Alexei Kornev's book Play 1.d4 d5 2.c4 e6!, published by Chess Stars. The contents page of the book is available at the link. It's a repertoire book from Black's perspective. Kornev writes that after 5.e4 "Black must find several very precise moves in order to reach equality".
> 2 votes

# Answer
Since White gets a significant advantage at once with with 5.e4, I doubt that anyone has ever written a book about it.
> 0 votes

---
Tags: opening, queens-gambit-declined
---


# Question
Title: Can you really learn from playing against computers just like when playing against humans?
I am wondering whether or not playing against chess against a computer will help you get better as quickly as playing against humans.

The motivation for this questions come from video gaming. I used to play a certain video game called *Rome:Total War* a lot, which is a game in which you control 100s of troops in a battle set in ancient times. It also is a tactical and strategical game like chess, but the 2 are not really very similar in any other respect.

In that game, I avoided playing against AI at all costs. That is because they play in a totally different way from humans, and you didn't really learn to play against humans from playing against the AI.

I myself have noticed that if I use some chess programs, the same kind of things happen. If I put it at a very low level, the computer still makes some good moves, however, if you capture something with your Queen, while the captured piece is protected by a pawn; the pawn won't take it, because the computer is trying to play terribly. This is totally not how humans would play, quite the opposite actually.

So, my final question is: If you play x matches against the computer set at a comparable Elo rating, would you learn as much as playing X matches against a human with the same Elo rating?

# Answer
I read an article in chess life about a man who won an significant open tournament even though he was unrated when he entered. He had practiced only against the computer.

I myself have learned a lot of what I know from computer programs. It is very difficult to find good players here and the computer is always available. From what I have read you learn most when you play against a player who is just a little better than you are. The computer allows you to control the level of play of your opponent. This is most effective when you opponent can tell you afterward what you did wrong and what you did right, so you will want to have the computer analyze the game afterward.

I would recommend also using books of games (or a database of games) where you can go over the analyzed games from players about your own strength. I have one of my grandfathers books which is a collection of games by Capablanca called "The Immortal Games of Cabablanca" the games early in his life helped me a great deal. I couldn't understand his later games enough to get much out of them.

To conclude, you can learn from playing a computer. They will play at the set level of play and can analyze your games, however use other sources to help you advance as well.
> 10 votes

# Answer
The computer is a calculator. It does not think but just calculates. As a result, it is very good at tactics, seeing deeper as the level is increased. I've been playing the computer exclusively for the past 8 months or so, generally at a medium setting to have a better chance to make a combination against it. I find that it does help sharpen my tactics, since I must have a very deep combination to beat it since it does not make calculating mistakes, while conversely, I must calculate its tactics very carefully if I want to avoid losing. I find that the best strategy to use against it is a positional, constricting game, not allowing it free rein for its tactics. Since it does not "think" like a human, it does not understand strategy. For exanple, if I mass my troops behind the lines for a kingside attack, it has no idea what I'm doing, and it might be too late to use saving tactics when I've finally encroached on the king position. In that sense, it can help you to become better at strategical thinking. So to anwswer your question, I think that playing the computer can help you to a limited extent to develop you game for use against humans. It will sharpen your tactics, but as explained, it wil not help you as much against a human who understands strategy and can see what you are planning if you are using a positional approach as opposed to an open game, tactical approach. By extension, it would follow that a match against a human at a certain rating would teach you more than a match against a comnputer of that rating.
> 4 votes

# Answer
I would say that playing against engines helps a lot both in the positional and tactical aspect, but you should acknowledge that human players' pattern repertoire is stricter than the one of a computer. This means that, given a human and an engine at the same strength, the engine's moves will surprise you more than the human ones on average.

I disagree with CConero's answer about engines being good at spotting tactics and bad at positional plans. In fact, positional plans are nothing but prolonged tactics, with an added layer of fogginess due to the inability of the player to exactly calculate the following moves.

Engines are probably *less better* than humans at positional play than they are at tactical play - this is due to the human's capacity of absorbing the "dead labour" of chess books which engines can't read for now (as far as I know) - but they still are better than humans at positional play.

As a support for my argument, notice that many positional strategies of today's top players (the most notorious being the flank pawns' pushes) are borrowed from engines' ideas.
> 0 votes

---
Tags: engines
---


# Question
Title: Albin countergambit question about a line
In the albin countergambit, after this line:

1. d4 d5 2. c4 e5 3. dxe5 d4 4. e3 Bb4+ 5. Bd2 dxe3 6. fxe3 Qh4+ 7. g3 Qe4 8. Qf3 Bxd2+ 9. Nxd2 Qxe5  Why is the position better for black? Is it the fact that white has three pawn islands whilst black only has two? It's -1 for black according to stockfish and 60% winrate for black according to Lichess.

Is there a reason I'm not seeing?

Thanks!

# Answer
The main reason in my opinion is that white has (scatteredly) expanded more than their position allows them to. it's important to keep a tight structure in these situations, which they have not managed to do.

In fact, their king is in danger for two reasons:

* They need at least three tempis to castle, since queenside castle looks very dangerous
* The main defender of their position, the essential e pawn, is isolated and can be defended for now only by their queen, so it already is a target.

In essence, black is ready to launch an attack and white is probably already late to defend.
> 2 votes

---
Tags: opening, queens-gambit
---


title: Castling on King side

text:
# Question
Title: Castling on King side
This is a quiz from a chess website. The challenge is to castle on King Side. White to play. How can we do this ?

# Answer
* bypassing the position's illegality
* assuming that White's goal is to castle kingside and that Black aims to prevent it,

then :

> 1.Bg2 is mandatory: we won't ever castle kingside if the Rh1 moves or is captured, so 1.Bg2 or 1.Ng2 is necessary to prevent 1...Bxh1. However, after 1.Ng2? Nxf2! we can prevent 2...Nxh1 only by moving Rh1 or Ke1, losing castling rights.

But after

> 1.Bg2 Bxg2 2.Nxg2 Nc6
> White still needs many moves to get rid of the Nh3 that controls g1. Meanwhile, Black threatens ...Nd4 forking the checking squares c2 and f3 for which they would force the Ke1 to move.
> 3.c3 Ne5 (aiming at d3 or f3) is insufficient, so White must play
> 3.Na3 Nd4 4.Nh4 to parry the threats.

Alas,

> 4...Ng1 is then decisive, when 5...Ndf3 cannot be parried: either the Rh1 or the Ke1 will have to move without castling.

As a conclusion :

> White won't be able to castle kingside if Black tries to prevent it.
> 6 votes

---
Tags: puzzles, castling
---


# Question
Title: Are cyborg (human+computer) players really better than the best chess engines?
I saw this rating score chart recently:

Is it true that cyborg chess players are (that much) better than the best chess programs by themselves?

# Answer
Yes, it is true that "cyborgs" are better than the best chess engines. That's why the best correspondence chess players still beat engines. (Sort of. By far the most common result of such games from the opening position is a draw.)

See source (part 2 can be found from the same link), which is an interview with a former correspondence chess champion.

> **Today chess engines are much stronger than the best humans and many people wonder about the role of humans in correspondence chess. What can you do that the engines cannot do?**
>
> It is indeed impossible to achieve any significant result in today’s correspondence chess without engines and databases. But we humans play, not the engines, and the input of humans mainly affects two areas: a) the choice of a suitable opening, and b) steering the engine toward (or away) from certain types of position.
>
> If you want to be successful in top correspondence chess you can only play a certain set of openings because you simply cannot afford one single sub-optimal move – if you do, you will sooner or later regret it. That’s as certain as death and taxes.
>
> How well you guide your engines depends on your general chess knowledge. The better your chess knowledge (the significance of pawn structures, good bishop, bad bishop, etc.) the better you will do here – today’s engines are very strong but they still misjudge positions. If you have enough time and patience and composure you can feed the computer with more good ideas than your opponent – exactly the process described by former World CC Champion GM Ron Langeveld in an interview on the ICCF website.
> 7 votes

# Answer
At this point in time in my opinion the human factor in a computer + human vs computer game might still be playing a difference, although I'm not aware of any experiments in this field done recently.

Given the speed of improvement of computer chess compared to the human one, I think that in this scenario the human's help will asimptotically tend to get close to 0.
> 1 votes

# Answer
Garry Kasparov said “For a period of about ten years, the world of chess was dominated by computer-assisted humans.” Eventually, AI alone dominated, and it’s worth noting that today the stratagems used by AI in many games baffle even the greatest masters
> 0 votes

---
Tags: rating, computer-chess, elo
---


# Question
Title: Can one side force a loss in regular chess?
Chess is unsolved, so there is no known optimal strategy for one side to force a win or a draw.

However, is there an optimal strategy to lose? Consider a variant where checkmate results in a loss, but all other rules are the same as regular chess. Is there a known optimal strategy to win or force a draw?

For example, can one side force the opponent to checkmate (assuming the opponent tries to avoid checkmate)? If not, can one side force a draw by rules like stalemate, threefold repetition, or the fifty-move rule? Or is this as hard to solve as regular chess?

# Answer
There is likely not a way to force a loss. Selfmates are relatively rare, and one can probably not be forced from the opening position.

The best plan, paradoxically, is likely to try to capture as many of the opponent's pieces (but not pawns) as possible, while keeping your own pieces to be better able to force your opponent. The opponent's pawns are kept because they have very little choice as to where they can move, and can also be easily blocked to avoid the opponent moving them before you want them to. For example, in the following position, the f-pawn is blocked and the king cannot move, so Black has no choice but to advance the g-pawn and will have to checkmate White in two moves:

```
[FEN "3Q4/8/8/4N3/6p1/7k/5p2/5N1K b - - 0 1"]

```

> If not, can one side force a draw

Well, if checkmate indeed cannot be forced, then almost by definition a draw could be forced. The game can't go on forever, after all. If nothing else, the players will eventually run out of pawns to move or pieces to capture, and the 50 move rule will come into play.
> 14 votes

# Answer
As far as I know, there is no chess variant that has been investigated that is exactly as you describe. However, antichess is a quite similar concept. The objective is to lose all your pieces/be stalemated, and it is required for you to take a piece if you can. It was weakly solved to be a win, starting with 1. e3. It is still interesting, however, as many of the lines are extremely long (over 100 moves).

In order to answer your exact question, it would be fairly difficult, but might be slightly easier to solve than regular chess. A powerful computer would likely be needed in order to figure it out.
> 9 votes

# Answer
Finding the optimal strategy requires the investigation of pretty much all (pretty much, in the grand scale of things) the positions that are possible to get to from the start.

While developing a computer program that plays extremely well in chess (or other similar games) is a solvable task—actually, it is a solved task somewhere in the beginning of the XXI century—finding and proving an optimal strategy **is a totally different problem**. Chess is hard to fully analyze because of the large number of possible positions.

To go more formal, consider Shannon number `10^120` which is a lower-bound on the game-tree complexity of chess. It is true that the sensible games would go much lower to around `10^40`, but it will not matter too much.

For the game variant you describe, one has to find the *Shannon-like* number to say about the feasibility of finding the optimal strategy. However, simply by looking at the rules, I doubt it would result in something that is feasible.

Thus, I don't expect an optimal playing strategy for this variant to be found any time soon. While it might be slightly easier than for regular chess, the complexity will still be enormous.

NB: Antichess example is different because of the introduction of the compulsory capture, which severely reduces the number of possible variations.
> 7 votes

# Answer
Forcing self-mate can be done from certain positions, the one forcing their opponent to checkmate them is usually far ahead in material. When I was a teenager (a long time ago) I actually studied the art of self-mate.

There is a game in Chess Companion where one player gave the other queen odds and the one with the extra queen had to force self-mate (and achieved it!). From that game I learned the technique.

Obviously it is not forced from the opening position.

To achieve it you have to be far ahead in material to restrict your opponent's legal moves. Their final move will be to capture one of yours that is giving check. (I can't unfortunately remember how it's done).
> 3 votes

# Answer
What a great question.

One important mathematical model for chess is Combinatorial Game Theory. Under the vanilla version of this beautiful theory, developed by Conway, Berlekamp & Guy, one loses when one has no legal moves. One modification of the theory is so-called "misère" (a term taken from card-games) where one *wins* when one has no legal moves.

A game and its misère form thus share the same game tree. They just have opposite values assigned to the leaf nodes. One can derive values for all other nodes in the game trees by working back from the leaf nodes. One amazing feature is that the value of non-leaf positions between misere and non-misère versions of the same game can be very similar.

For example, the winning strategies for the well-known game of nim are essentially the same. It's only with the winning player's final choice that they decide to take one more or one less match from the last non-singleton pile.

Another way to say this: players vie for strategic dominance. Once that is achieved, then one could force the opponent to do a number of different tasks: be checkmated, to checkmate, to send king on journey to occupy every square of the board, etc. The difference between these tasks would be secondary - once strategic dominance is achieved. In practice, it's not as clear cut: part of achieving strategic dominance in chess involves threats of mating. An attack may sacrifice strategic dominance for a winning tempo advantage in order to checkmate quickly. But nevertheless, regular chess and misère have much in common.

Now chess problemists have long had a misère genre they term "selfmates". (The problem database PDB contains over 58,000 of these today! Type g='s#' in the window https://pdb.dieschwalbe.de) These are about the dynamics of forcing a nearly-dominated opponent to execute the victory task, in an interesting way. They tend to involve long series of checks (so-called entailing moves in combinatorial game theory). For example https://pdb.dieschwalbe.de/P1014331 takes 10 moves. All this means that the initial game array is unpromising as a start for a selfmate. If I had to bet (and of course we can never know), I would hazard that misère chess is a positional draw from the starting position. I think this is true even if it turns out that orthodox chess is a win for White, because in misère, tempo does not have the same value.
> 3 votes

# Answer
**Almost surely not**

See Wikipedia on chess handicaps, in particular this game.

> In response for receiving the queen, Black undertakes to force White to checkmate Black.
>
> Paris vs. Marseilles, correspondence 1878 (remove White's queen)

Black successfully loses, but only by starting with an extra queen. This means Black can achieve a "winning position", pin White's remaining pieces, and set up a self-mate. Without the extra queen it's extremely unlikely Black can lose against an opponent who's trying to not win - that's why it's a handicap.
> 0 votes

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Tags: chess-variants, selfmate
---


title: What is the Colorado Gambit?

text:
# Question
Title: What is the Colorado Gambit?
I recently heard of an opening called the "Colorado Gambit". My chess opening is pretty weak and my friend suggested I might try it. What is Colorado Gambit and what is the reasoning behind the moves?

# Answer
```
  [FEN ""]

1. e4 Nc6 2. Nf3 f5?!

```

This is the Colorado Gambit.

If you are looking for a good solid opening, try looking up some of the following:

This is more than enough for the beginning. All the best!
> 7 votes

# Answer
First, an off-beat opening like this isn't going to help you improve. You might get some cheap wins but you aren't learning anything.

However, I've never seen this gambit and am fairly intrigued by it. The natural moves that you're likely to see (e5,Nc3,d3) score really bad for white. White can only really play 3.exf5 after which 3...d5 wins the pawn back, gives black an equal share of the center and a lead in development. The resulting pawn structure reminds of a mirror-image Boleslavsky structure in the Sicilian in that black could get receive a very good endgame if he could get e5 in and trade it for white's d-pawn. I'm not sure how all the tactics work out (especially after 5. Bb5) but it looks interesting enough to take a look at especially given how little theory there is in 1...Nc6.
> 0 votes

# Answer
9 years later...

The idea behind the Colorado Gambit is that if Black successfully exchanges their f5 pawn with White’s e4 pawn, they might be able to gain a foothold in the centre and use the half-open f file for their Rook. If Black successfully gains back the pawn and manages to play ...e5, they’ll be fine. This is helped by several traps lying in wait for an unwary White.

On the other hand, Black seriously weakens their King’s position and the h5-e8 diagonal. And after the mainline 3.exf5 d5, the e5 square is weak along with a backward “e” pawn.

```
[Event "Colorado Gambit"]
[FEN "RNBQKBNR/PPPPPPPP/8/8/8/8/pppppppp/rnbqkbnr b KQkq - 1"]

1.e4 Nc6 2.Nf3 f5?! 3.exf5 d5 4.Bb5! {White wants to exert control over the e5 square by exchanging pieces that control it} Bxf5 5.Ne5! Bd7 (5...Qd6?! 6.d4 Nf6 7.O-O e6 8.Bf4) 6.Bxc6! (6.Qh5+?! g6 7.Nxg6 Nf6 8.Qh4 hxg6! 9.Qxh8 Nb4! {Black has good counterplay}) 6...Bxc6 (6...bxc6? 7.Qh5+ g6 8.Nxg6 Nf6 9.Qh4 {Now there's no more ...Nb4}) 7.d4! (7.Qh5+?! g6 8.Nxg6 Nf6 9.Qh4 Rg8 10.Nxf8 d4! {With some complications}).

```

White has control over the central e5 square and Black’s backward “e” pawn. White also has 3 minor pieces to fight for the e5 square while Black has only 2 pieces to defend it.
> 0 votes

---
Tags: opening, gambits
---