# Question
Title: Why does Stockfish suggest capturing a bishop in this position when my opponent can fork my king and rook?
The position in question is:

```
[FEN ""]
[StartPly "13"]

1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. Nc3 e5 5. Ndb5 Bb4 6. Bg5 Bxc3+ 7. bxc3 Qa5 8. Qd5 Nge7 9. Nd6+ Kf8 10. Qxf7# 1-0

```

It's black turn and the engine is recording to take the hanging bishop, but doesn't Nc7+ fork the King and the Rook? Stockfish is still showing a negative evaluation for this position.

**Am I missing something important?**

# Answer
> 10 votes
White does indeed fork the king & rook after Nc7+ - but after Nxa8, the knight is not escaping, so Black is at worst even on material.

```
 [FEN ""]

 1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. Nc3 e5 5. Ndb5 Bb4 6. Bg5? Qxg5 7. Nc7+ Kd8 8. Nxa8

```

After something like ...b6 followed by Bb7, the knight's a goner. White can get at most one pawn for the knight (after Nxb6), which leads to a material imbalance of R+P vs B+N. This particular imbalance is roughly equal, although I've also read that the side with two minors tends to be favored in middlegames since they represent two useful attacking pieces while the extra pawn is only useful in the endgame. Moreover, Black is also way ahead in development (even if he does take some time to round up the knight on a8).

In short, you're not missing anything important insofar as White does not end up grievously behind in material - but Black has more than enough positional compensation.

# Answer
> 11 votes
I agree with the other two answers, but I feel like I also need to comment on the beginning of the game since there was A LOT more important stuff there than just the answer to why Qxg5.

This is very similar to a Kalashnikov Sicilian by transposition with the exception that the knight is on c3 instead of a pawn on e4, but the ideas are very similar. In particular, the moves Bb4, and Bxc3. The doubled pawns were not worth it, and I will go into why below. There are fairly extensive notes in the game below about the opening play.

```
 [FEN ""]

 1. d4 (1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 5. Nb5 d6 {This is a normal move order to get to the Kalashnikov Sicilian. Your game is not quite a Kalashnikov, but it is very close, and the strategic similarities are relevant. } (5... a6 {Or this. Ulf's favorite, leading to an endgame.})) 1... c5 2. Nf3 cxd4 3. Nxd4 Nc6 (3... d5 $1 {Take the center!}) 4. Nc3 e5 $2 {This is premature since the N is on c3 instead of e4 having been played. You also have to have a feel for how the hole on d5 needs to be managed. In general, you do not want to create a backwards pawn on an open file.} 5. Ndb5 {Nd5 is now a threat winning on c7.} Bb4 $2 {In similar structures in the Kalashnikov, the bishop never goes to b4, as you almost never want to take on c3. The doubled pawns are not worth it for reasons I will give below, but also because after e5, you have weakened the dark squares around your king. The game actually showed what happened when a knight got to d6.} (5... a6 $1 6. Nd6+ Bxd6 7. Qxd6 Qe7 {Is a main line that Ulf Anderssen plays with the difference being that the N is on c3, instead of e4 being played, so your options were limited to just a6.}) (5... d6 $4 6. Nd5 Qa5+ 7. Bd2 $18 {Is the simplest.} Qxb5 $4 8. Nc7+ Kd8 9. Nxb5) 6. Bg5 Bxc3+ $2 {In many similar positions, the Nc6 will come to d4 with strong threats, but here, giving up the bishop takes that off the table. At least, I would wait until white wastes a tempo with a3, forcing your decision. In addition, a Nd4 gums up any white counterattack down the d-file, and limits white's space.} (6...Qxg5 $19 {This is MUCH stronger here.} 7. Nc7+ Kd8 8. Nxa8 b6 {And black is way ahead in development, and more importantly, it is hard for white to finish development, and catch up.}) 7. bxc3 Qa5 $2 (7... Qxg5 {As you, and the others mentioned.}) 8. Qd5 Nge7 $4 9. Nd6+ {We see the dark squares have the final say due to bxc3 earlier.} Kf8 $2 10. Qxf7#

```

# Answer
> 6 votes
In addition to Allure's comments. Two pieces is favourable to a rook in a position like this where there's no clear squares for the a8-rook to attack, but lot's of squares in the center for the two minor pieces to control.

Black is definitely better after the exchange.

---
Tags: analysis, stockfish, evaluation, candidate-move
---


# Question
Title: Do any national chess bodies not strictly follow FIDE rules?
There are some subtle differences in the rules of chess used in different un/rated competitions. For example, chess.com never considers King + Bishop sufficient mating material (specific example here).

Do all national chess bodies (e.g. AICF, FEDA etc) strictly adopt FIDE rules, or do some make their own variations like chess.com does?

The more 'human' way of asking the same question is like this: Is chess played by exactly the same rules around the whole world, or are there subtle variations in the rules of the game from country to country, as is the case with some games/sports e.g. rugby union?

# Answer
I do not know the rules for every country, but if the USCF and ICCF are any indication, most bodies have their own tweaks to tournament rules. The rules for the actual piece movements are consistent.

The exception is when a tournament is both nationally-rated and FIDE-rated, then FIDE rules take precedence.
> 8 votes

# Answer
> Is chess played by exactly the same rules around the whole world?

No. To be honest, as outlined below, even FIDE rated chess is played by slightly different rules because the FIDE Laws give this flexibility

According to the preface of the FIDE Laws of Chess:

> A necessary condition for a game to be rated by FIDE is that it shall be played according to the FIDE Laws of Chess. It is recommended that competitive games not rated by FIDE be played according to the FIDE Laws of Chess.

Only games which are going to be rated by FIDE have to be played by the same rules but there are cases where games are not going to be FIDE rated where it makes a lot of sense to depart from parts of the FIDE Laws.

One obvious example is children's chess. In December I was one of several arbiters in a large room where several children's tournaments were being played, with different strength players in each and slightly different rules regarding clocks and illegal moves. For the stronger players in the FIDE and nationally rated tournaments clocks were used and the "2nd illegal move loses" rule was strictly enforced. In the weaker, unrated tournament there were no clocks (unless a game looked like taking too long in which case a clock was introduced with 5 minutes per player) and a loose "3 illegal moves loses the game" rule.

The English Chess Federation publishes its tournament rules which outline some of the differences. This is what it says for non-FIDE rated games:

> **Section D – Optional rules for events that are not FIDE-rated**
>
> 1. FIDE recognises for its own events and matches only one system of notation, the Algebraic System. For events that are not FIDE-rated, organisers may permit the use of descriptive notation.
> 2. For events that are not FIDE-rated, organisers may permit the use of adjudication.
> 3. For Under 11 Rapid Chess events that are not FIDE-rated – i.e. those restricted to players who are under the age of 11, defined by either the calendar year or the academic year – the number of illegal moves that results in the loss of a game may be increased from two so long as it is prescribed in advance in the regulations of the event.
> 4. Where no arbiter is appointed, e.g. in an evening league match, then the organiser is empowered to make decisions otherwise the responsibility of the arbiter with respect to Article 11.3.2.1. In the case of a team match, the organiser is also empowered to delegate this responsibility to the match captains.

Note that there are also areas of the FIDE Laws where there is a choice defined with a default. Here is how the ECF (see above document) handles one of the more contentious ones, the one which results in a zero time default rule if the organizer doesn't specify a more sensible time in advance:

> According to Article 6.7.1 of the FIDE Laws of Chess, the regulations of an event shall specify a default time on the entry form. Should the organizer fail to do so, the default time shall be 30 minutes for a Standard-play game and 10 minutes for a Rapid Chess game. Blitz games shall have no default time – the time shall just be allowed to expire.

The document also usefully highlights other areas where FIDE gives options (which naturally give rise to even FIDE rated chess being played by slightly different rules in different tournaments):

> **Section C – Optional Rules**
>
> 1. According to Article 10.1 of the FIDE Laws of Chess, the regulations of an event may specify a different scoring system. For example a player who wins his game, or wins by forfeit, scores three points (3), a player who draws his game scores two points (2), a player who loses his game scores one point (1), a player who loses by default scores zero points (0). If not specified, normal scoring is used (1, ½, 0).
> 2. Leaving the playing area:- According to Article 11.2.4 of the FIDE Laws of Chess, the regulations of an event may specify that the opponent of the player having the move must report to the arbiter when he wishes to leave the playing area. If this is not specified, there is no obligation for the opponent to communicate his intention to leave.
> 3. According to Article 11.10 of the FIDE Laws of Chess, the regulations of an event may specify that a player cannot appeal against any decision of the arbiter, if he has signed the scoresheet. If not specified, the player may appeal even after signing the scoresheet. It is strongly recommended that an Appeal Committee should be set up in advance.
> 5 votes

# Answer
A list of differences between USCF and FIDE rules: http://www.uschess.org/images/stories/FIDEInformation/uschess-fide-rules-twocolumn-comparison-feb2020-rev-2.pdf

Some highlights: Can an arbiter call a flag, can you call your own flag, can an arbiter call a touch violation without a claim, how complete a score you need to get a flag win, when you can claim repetition/50 move, unlimited vs. 10-move illegal move lookback and can you promote to an inverted rook.

(Calling your own flag under USCF rules stops your opponent from continuing to bring their score up to date. So if you know they're outside what's required regarding scorekeeping to claim a win....)
> 4 votes

---
Tags: rules, fide
---


# Question
Title: Can Black save this Knight vs Bishop endgame with a pawn down?
After playing horribly in the opening, my opponent played a couple of suboptimal moves which suddenly allowed me to exchange some pieces and get the following unclear position.

I thought about giving the h pawn away, giving White two potentially useless h pawns if he captures gxh4. However, I thought that making use of it would require trading my g pawn for the White f pawn, which seems to be impossible.

```
[White "Villain (2200)"]
[Black "Hero (2000)"]
[fen "2B3k1/5pp1/4pn2/8/3P3p/4P1PP/5P1K/8 b - - 0 1"]

1... Ne4 2.Kg2 hxg3 3.fxg3 *

```

The position after fxg3 was when I needed to formulate a plan. I thought of several options, all of which are more or less passive defenses, as I think moving my pawns would only weaken them and gain nothing in any position.

**First idea:** Leave my king on g8, and sacrifice the knight to get a fortress. More precisely, force White to move his pawn to g6 and trade the knight and f7 and e6 pawns for White's other pawns (king, pawn g6, light-squared bishop vs. king g8, pawn g7).

```
[Event "Draw"]
[fen "6k1/6p1/3K2P1/8/4B3/8/8/8 b - - 0 1"]

```

However, I didn't see any way to force this: if White can keep any pawn not in g6, he wins if I sacrifice the knight.

**Second idea:** Leave my king to protect the g pawn. This forces White to exchange the e pawns. Then I can use my king to stop the passed d pawn and my knight to stop the kingside pawns. However, from what I calculated (and analyzed afterwards), it seems it is not sufficient. This is just an example of what I think could happen; I haven't checked every move thoroughly, but the general idea is still the same: Black can block White's d pawn, but White can always force a win due to Black knight's limited mobility and zugzwang.

```
[White "Villain (2200)"]
[Black "Hero (2000)"]
[fen "2B3k1/5pp1/4p3/8/3Pn3/4P1PP/6K1/8 b - - 0 3"]

3... Nd6 4.Ba6 Kf8 5.Bd3 Kg8 6.Kf3 Kf8 7.e4 Kg8 8.d5 exd5 ( 8...Kf8 9.e5 ) 9.exd5 Kf8 10.Ke3 Kg8 11.Kd4 Kf8 12.Kc5 Ke7 13.Kc6 g6 ( 13...f6 14.Kc7 Ne8+ 15.Kc6 ) 14.Kc7 Ne8+ 15.Kc6 f5 16.g4 fxg4 17.hxg4 g5 18.Bg6 Nf6 19.d6+ Kd8 20.Bf5 Ng8 21.Kd5 Nf6+ 22.Ke6 Nd7 23.Kf7 Ne5+ 24.Kf6 Nc4 25.d7 1-0

```

During the game I remembered that KBPvKN with the advanced pawn can be a win in some positions. However, I didn't remember when that happens, and I also couldn't see any way to force the exchange of all kingside pawns before allowing White to advance his pawn this far. In post mortem, I was able to blitz a win against the opponent in a position similar to this (without the g pawns), even though he claimed it is an easy draw.

**Third idea:** Use my king to stop the d pawn, exchange my e pawn to White's d or e pawn and force him to defend the isolated pawn so he can't make progress. This is what I decided to do in the game, making by endgame skills look ridiculous.

```
[White "Villain (2200)"]
[Black "Hero (2000)"]
[fen "2B3k1/5pp1/4p3/8/3Pn3/4P1PP/6K1/8 b - - 0 3"]

3... Kf8 4.Ba6 Ke7 5.Bd3 Nf6 6.Kf3 Kd6 ( 6...e5 7.dxe5 Nd7 8.Kf4 Ke6 9.Bc4+ ) 7.Bc4 Nh7 8.h4 Nf6 9.g4 Nd7 10.g5 f6 11.Kg4 Nb6 12.Bb3 e5 13.gxf6 gxf6 14.h5 Ke7 15.h6 Kf8 16.Kf5 1-0

```

Something like 6...e5 was my idea but I couldn't make it work in any position. For example, after 6...Kd6 7.Bc4, I realized the f7 pawn would hang. I saw no other way to make my position any better: any pawn move would weaken them and any king move would give White more space. Only after 13.gxf6 I realized that my plan of moving king to stop the d pawn allowed White's king to break through easily.

**Question:** Did I miss something? Was one of these plans drawing after all, or is there a resource I didn't see, or is the game simply lost?

# Answer
> 3 votes
I think it is good to notice the possibility of different fortresses, like the one you mention, and of course the wrong coloured bishop for the h-pawn. But to turn reaching such a fortress into a "plan" is way to early in this position.

I think fxg3 was probably ok. At the first glance it looks ugly that now there are white prospects for a passer on the d-line and on the h-line, but your g and f-pawns can actually deal with the white g and h-pawns. Against g4 and h5 you should play f6 and against h4 and g5 (like in the game) you could have played g6. These setups prevent an h-passer.

But maybe 10.f6 was still ok. Then you certainly should have played 11…fg 12.Kg5 Nf8 which prevents the intrusion of the white king. But even here h5-e4-e5-h6 and Kf6 might just win for white.

An engine will be able to come up with better lines, but my feeling is that

* Keeping your pawns compact.
* Keeping the white king away.
* Preventing a h-passer.

might have earned you a draw. (Coincidentally you violate all these guidelines with the move e5, after which you are surely completely lost.)

# Answer
> 3 votes
In the second idea, it looks to me like 8... exd5 is a mistake. I would try 8... e5 instead, accomplishing your idea of putting the pawns on dark squares, followed by f6, Kf8 and Ke7. If the white king comes to g6, you just move back to f8. The knight will always have a move that the bishop doesn't cover. The most challenging idea looks like playing h4 and g5. For example:

```
[White "Villain (2200)"]
[Black "Hero (2000)"]
[fen "2B3k1/5pp1/4p3/8/3Pn3/4P1PP/6K1/8 b - - 0 3"]

3... Nd6 4.Ba6 Kf8 5.Bd3 Kg8 6.Kf3 Kf8 7.e4 Kg8 8.d5 e5 ( 8...exd5) 9. h4 Kf8 10. g4 f6 11. g5 fxg5 12. hxg5 Kf7

```

and it doesn't look to me like White can make progress. If White brings the king to support the g-pawn instead advancing the h-pawn, Black could recapture on f6 with the king and that also looks like a fortress.

I haven't checked the moves leading up to 8. d5.

# Answer
> 1 votes
What if you don't play `fxg3`? It seems that white `h-pawn` and `g-pawn` that can create a passer is a big head-ache for black. It does not look like white can capture `h-pawn` easily, their doubled pawns on the `h-file` would not look very good.

Maybe in your initial position you could play `Kh7`, and then to `g6`. The `f7-pawn` is safe while the knight is on `f6`.

# Answer
> 1 votes
In your second plan, you say:

> Black can block White's d pawn, but White can always force a win due to Black knight's limited mobility and zugzwang.

That is White's hope for sure, but it should not happen. For instance, in the line you give, 18...Nf6?? is very collaborative: why not 18....Nd6 with a clear draw ? Your knight is not going to be zugzwanged since White cannot control c4, b5, e4, f7, e8, c8 and b7 at the same time. If the white king aims for f5, simply Kf6 will stop him.

```
[White "Villain (2200)"]
[Black "Hero (2000)"]
[fen "2B3k1/5pp1/4p3/8/3Pn3/4P1PP/6K1/8 b - - 0 3"]

3... Nd6 4.Ba6 Kf8 5.Bd3 Kg8 6.Kf3 Kf8 7.e4 Kg8 8.d5 exd5 ( 8...Kf8 9.e5 ) 9.exd5 Kf8 10.Ke3 Kg8 11.Kd4 Kf8 12.Kc5 Ke7 13.Kc6 g6 ( 13...f6 14.Kc7 Ne8+ 15.Kc6 ) 14.Kc7 Ne8+ 15.Kc6 f5 16.g4 ( 16.h4 Nd6 17.Bc2 Ne8 18.g4 {White gets a h-passer, but the g-pawn gives enough counterplay for Black.} fxg4 19.Bxg6 Nd6 20.Bd3 g3 21.Bf1 Nf5 22.h5 Kf6 {is drawn as well}) fxg4 17.hxg4 g5 18.Bg6 Nd6! ( 18...Nf6? 19.d6+ Kd8 20.Bf5 Ng8 21.Kd5 Nf6+ 22.Ke6 Nd7 23.Kf7 Ne5+ 24.Kf6 Nc4 25.d7 ) 19.Bd3 Ne8 20.Bg6 Nd6 21.Kc5 Nb7 22.Kd4 Kf6 23.Bd3 Nd6

```

Admittedly, earlier in your line, White could aim for a passed h-pawn instead of exchanging with g4. And 8.d5?! doesn't look very smart either. But the position should be drawn anyway.

Anyway, this "second plan" looks like the most natural: ask white to demonstrate how he plans to makes progress, exchanges pawns and block the passer on a dark square.

# Answer
> 0 votes
I know I am late to the party, and it should be a draw, but none of the answers really hit on the easiest plan, and that was f5, making is impossible for white to create a passed pawn, except for an h-pawn, but the white bishop cannot control the queening square.

The structure is similar in reasoning to the question I posted here.

f5 looks weakening, but the only weakness, e6, is easily defended by the black king, and the white king does not have time to run to d7 to help the bishop attack it, or the black knight will wreak havoc.

```
 [FEN "2B3k1/5pp1/4pn2/8/3P3p/4P1PP/5P1K/8 b - - 0 1"]

 1... Ne4 2. Kg2 hxg3 3. fxg3 Nd6 4. Ba6 (4. Bd7 Kf8 5. Kf3 Ke7 6. Ba4 f5 7. Kf4 Kf6 8. h4 Nf7 9. Bc2 g5+ 10. Kf3 (10. hxg5+ Nxg5=) 10... e5 $1 11. Bb3 (11. d5 e4+ 12. Kg2 Ke5 13. Kf2 gxh4 14. gxh4 f4= {Wrong bishop after the knight takes on d5 soon.}) 11... exd4 12. Bxf7 dxe3 $1 13. Bc4 gxh4 14. gxh4 Kg7=) 4... f5 5. Kf3 g5 6. h4 gxh4 7. gxh4 Kf7 8. Kf4 Kf6 9. Be2 Ne4 10. Bf3 Nd6 11. Bc6 Nc4 12. h5 e5+ 13. dxe5+ Nxe5 14. Bd5 Nd3+ 15. Kg3 (15. Kf3 Kg5 16. Bf7 $4 Ne5+ $19) 15... Kg5 16. Bf7 f4+ 17. exf4+ Nxf4=

```

# Answer
> -2 votes
Against a human it could certainly happen. Black should not resign! But against a computer maybe, my intuition say no.

More importantly is how good are white and black at endgames. That could be worth more than a pawn.

I would play on as white and expect to win. But I always expect to win endgames:)

I would play on as black and expect to draw. But I am confident in my endgame play.

---
Tags: analysis, endgame, draw, minor-pieces
---


# Question
Title: Idea behind e-pawn sacrifice in Open Sicilian: Najdorf, Freak Attack (6. Rg1)?
There are 10 games in my database with this variation played on a high level and the White score is +6-2=2, almost always White is the elo-wise weaker player. The highest rated White player to employ this line is GM Tigran L. Petrosjan and he won his two games on a 2400+ level, against higher rated opponents.

Since it is played at such high level, repeatedly and with success, I suspect there is an idea to this sacrifice, but reviewing games and consulting the engine did not give full clarity. In fact the engine gives lines different to what is played, mostly going for Bf4 and trading queens.

The sacrifice in question is 8. g5!? (instead of say 8. Bg2), which compels Black to take on e4.

Only one Black player supported his Bishop with 10...d5, the rest retreated with 10...Bb7. My questions are: Why does White not only give, but provoke Black to take the pawn and why do most players not play ...d5 (after ...d5, f3 Bg6 and the position would seem very solid for Black)? Is it because they do not know the position and it looks as if the Bishop could be harassed and restricted after closing the diagonal?

```
[White "Petrosian, Tigran L (2568)"]
[Black "Smirnov, Pavel (2645)"]
[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 { B90 Sicilian Defense: Najdorf Variation } 6. Rg1 b5 7. g4 Bb7 8. g5 Nxe4 9. Nxe4 Bxe4 10. Qg4 Bb7 11. Bg2 Qc7 12. Be3 g6 13. O-O-O Bg7 14. f4 O-O 15. h4 Nd7 16. Bxb7 Qxb7 17. f5 Ne5 18. Qh3 Qe4 19. h5 Nc4 20. Rge1 Rfc8 21. hxg6 hxg6 22. fxg6 fxg6 23. Kb1 Qd5 24. Bc1 Rf8 25. Ne6 Qf5 26. Qxf5 Rxf5 27. Nxg7 Kxg7 28. Rxe7+ Kf8 29. Rh7 Kg8 30. Rh6 Kg7 31. b3 Ne5 32. Rxd6 Rf1 33. Re6 Ng4 34. Rexg6+ Kf7 35. Rxa6 Rd8 36. Rhd6 Re8 37. Rd4 Rg1 38. Kb2 Ree1 39. Rd7+ Ke8 40. Rh7 1-0

```

Here's a game where Black played ...d5:

```
[White "Nadj Hedjesi, B. (2311)"]
[Black "Milosevic, A. (2269)"]
[FEN ""]

1. e4 c5 2. Ne2 Nf6 3. Nbc3 d6 4. d4 cxd4 5. Nxd4 a6 { B90 Sicilian Defense: Najdorf Variation } 6. Rg1 b5 7. g4 Bb7 8. g5 Nxe4 9. Nxe4 Bxe4 10. Qg4 d5 11. f3 Bg6 12. f4 e6 13. Be3 Qa5+ 14. Bd2 Qb6 15. f5 Bc5 16. fxg6 Bxd4 17. gxf7+ Kxf7 18. Rg2 Nd7 19. g6+ hxg6 20. Qxg6+ Ke7 21. O-O-O Rae8 22. Rg3 Kd8 23. Ra3 Kc8 24. Ba5 Qa7 25. Bc3 Bc5 26. b4 Be3+ 27. Kb1 Qb6 28. Bxg7 Rhg8 29. Qf7 Rd8 30. Bh3 Rge8 31. Rxd5 exd5 32. Bxd7+ Rxd7 33. Qxe8+ Kc7 34. Rc3+  1-0

```

# Answer
I think that a lot of the answers to your various questions about "why this or that" come down to the fact that it is just very unexplored theory, and the black players are just using their best judgment, probably mostly on-the-fly since Rg1 is so rare. I have just 18 games in my database after 9...Bxe4, and 7 of those games were played by white players below master level. That is not a lot of practical practice.

As far as white having a lesser Elo-rating, I assume that I have most of the same games as you (I use Mega 2020), and for the most part, the rating differences are not that great, so I do not consider it a big deal. 5 of the 11, white out-rated black, and the other 6, black out-rated white. Only one had a huge disparity with a 2500 white player vs. a 2100 black player.

Obviously, the main idea is to get a lead in development where black has barely even started developing the kingside. The latter part of that sentence is the key. In addition, it seems to me that sometimes, it can also be hard to get that development going. For example, I think that instead of trading the Bf1, that a quick Bd2 and 0-0-0 may be even more dangerous, highlighting that inability to develop.

As to why the bishop goes back to b7, I think that it is much more natural. The bishop going to g6, while solid, could still come under attack by h4-h5. It is too early to tell, and most strong players would probably be weary of that. With the bishop on b7, it controls a lot of squares, and it almost forces white to trade the light-squared bishops since on d3, the white light-squared bishop will surely be blunted by the natural g6. Trading off a potential attacker in this position is, clearly, desirable.

There is a lot of room for analysis in this opening.

```
 [FEN ""]

 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Rg1 b5 7. g4 Bb7 8. g5 Nxe4 9. Nxe4 Bxe4 10. Qg4 Bb7 (10... d5 11. Bf4 {This developing move, stopping e5, is probably best.} (11. f3 Bg6 {And while solid, the kingside is still far from being developed, and the Bg6 may still become a target.})) 11. Bg2 (11. Bd2 g6 12. Bc3 e5 {If this is the computer's best suggestion, then I really like this as white.} 13. O-O-O {May even be more dangerous.} exd4 $4 14. Bxd4 Rg8 15. Bg2 Nc6 16. Bf6 Be7 17. Rge1 $18) 11... Qc7 {Trying to keep control of the h1-a8 diagonal.} 12. Be3 g6 {This is where I would rather have this on c3, really giving the black king nowhere to go.} 13. O-O-O Bg7 {And black has a solid pawn, but the position is very open, and tactical in nature.}

```
> 5 votes

---
Tags: sicilian-defense, gambits, sacrifice, najdorf
---


title: What is the definition of an "outpost"?

text:
# Question
Title: What is the definition of an "outpost"?
The Wikipedia definition of an "outpost" is this: “A position on the chess board where a knight is defended by a pawn from its same side.” Does it have to be a knight?

# Answer
> 5 votes
There is no "official" definition because there's no ISO standard for chess terminology, so the term means whatever the author wants it to mean, but I'd say the essence of it is that it is a "safe" and "advanced" square for a piece, where "advanced" typically means at least the 5th rank. As an analogy consider common non-chess definitions of outpost such as "an outlying or frontier settlement" or "a military base established in another country".

"A position on the chess board where a knight is defended by a pawn from its same side" is not only too restrictive by being limited to knights, but at the same time is too unrestricted because it would include something like a white knight on f3, which while protected, is hardly at an **out**-post; it's more of a "home base".

As for the "safe" part, it's a bit relative, but generally it means that it is not easy for the opponent to chase away or trade the piece. This may mean that the piece can't be chased away by pawns, because there are no pawns on the adjacent files or they are too far advanced, or because the pawn move to chase away the piece would come at a cost. Alternatively the opponent could trade it for a piece, but sometimes it's a bad tradeoff because the player who had the outpost might get some compensation such as a protected passed pawn. Or sometimes there is no way to trade it without sacrificing material, for example in a knight vs bishop scenario where the bishop is on the wrong color squares, so the only way to capture the knight is with a rook.

Finally, while not all outposts are for knights, perhaps most are; the reason for the emphasis on knights is due to knights being short-range pieces. Rooks and bishops can often be active from their home territory when on a good file or diagonal, but knights need to move closer to the action.

# Answer
> 3 votes
No, it does not have to be a knight.

It is really any forward square (5th rank or 6th rank), occupied by any piece (knight, bishop, rook, and more rarely since it can be chased away by less-valuable pieces, but even a queen sometimes). The piece usually applies uncomfortable influence over the opponent’s position.

For example, I have seen rooks planted often on d6, protected by a pawn (on e5 or c5, or even both). The rook exerts great pressure, but if taken, a strong passed pawn appears instead...trading one advantage for another.

It also really does not even have to be protected by a pawn, as long as it is, or can be, defended enough that you can continue to control it. A knight on e5 protected by a Re1 is a common example here.

P.S. GM Dofrman in the book, “The Method in Chess” has his own definition of an outpost: “an outpost is a square on a half-open file in front of an enemy pawn, situated on the 6th (for White - on the 3rd) rank.”

When I watched the videos on chess.24.com, even GM Jan Gustafsson seemed to be a little taken aback by his definition, thinking it should be more broad.

Personally, I think that his definition is a bit limiting.

---
Tags: terminology
---


title: Touch move and capture sequence

text:
# Question
Title: Touch move and capture sequence
When considering the touch move rule, I am still unclear about the legal sequence for a capture. Example, white intends to capture a took on a8 with rook on a1 (open file). Does white have to touch black's rook first? The way I read the rule, if white touches a1 first, they can only play a2 through a7, since touching a8 AFTER a1 violates the rule. What is the legal sequence?

# Answer
Here is what the FIDE Laws of Chess have to say:

> 4.3 Except as provided in Article 4.2, if the player having the move touches on the chessboard,with the intention of moving or capturing:
>
> 4.3.1 one or more of his own pieces, he must move the first piece touched that can be moved
> 4.3.2 one or more of his opponent’s pieces, he must capture the first piece touched that can be captured
> 4.3.3 one or more pieces of each colour, he must capture the first touched opponent’s piece with his first touched piece or, if this is illegal, move or capture the first piece touched that can be moved or captured. If it is unclear whether the player’s own piece or his opponent’s was touched first, the player’s own piece shall be considered to have been touched before his opponent’s.

So, if the first two pieces you touch are one of your pieces and one of your opponent's pieces then you must capture your opponent's touched piece with your touched piece. Order is irrelevant in this case.

If you first touch your piece and then one of your opponent's pieces which you cannot capture with your touched piece then you must move your piece even if you can capture your opponent's touched piece with one of your untouched pieces.

If you first touch one of your opponent's pieces and then one of your pieces but can't capture the opponent's touched piece with your touched piece then you must capture your opponent's touched piece if you can. Otherwise you have to move your touched piece.

Overriding these rules is the rule preventing you from making an illegal move. You may only move a touched piece or take an opponent's touched piece if that move is legal.
> 7 votes

---
Tags: rules, illegal-move, captures
---


title: How do we identify opening lines?

text:
# Question
Title: How do we identify opening lines?
How many opening moves are needed before we can identify that such moves fall into a particular well-known opening such as Ruy Lopez, London, kings gambit, an so on? And after such identifying moves, can we we say that such opening is already completed and the player is on his own for the development of his pieces?

# Answer
Openings are typically decided by ECO Codes.

So as few as one move and as many as 5-6 or more moves could decide an opening. For example, as soon as you play 1. b3 it is a Nimzo-Larsen attack. (A01)

As soon as 1. e4 c5 is played it is a Sicilian defence. (B20) But there are many variations. If the game continues 2. Nf3 e6 3. d4 cxd4 4. Nxd4 a6, it becomes the Kan variation. (B41) So on and so forth. You can find a full list of recognized openings and their ECO codes in the link above.

As for your second question, no, after the identifying moves have been played, the opening is typically not completed yet. For example, take this line of the Budapest gambit.

```
[FEN ""]
[Event "Budapest Gambit"]

1. d4 Nf6 2. c4 e5 3. dxe5 Ng4 4. Nf3

```

This is as many moves as it takes to recognize the opening as Budapest Gambit, Adler Variation (A52). However, you can hardly say the opening is over.

```
[FEN ""]
[Event "Budapest Gambit"]

1. d4 Nf6 2. c4 e5 3. dxe5 Ng4 4. Nf3 Nc6 5. Bf4 Bb4+ 6. Nc3 Bxc3 7. bxc3 Qe7 8. Qd5 f6 (8... Qa3)

```

This is a very common continuation to the Budapest Gambit, even though these moves aren't needed to identify it as such - it is all still theory. The player isn't "on his own", there are still many established lines to follow.
> 5 votes

# Answer
> How many opening moves are needed before we can identify that such moves fall into a particular well-known opening such as Ruy Lopez, London, kings gambit, an so on?

It depends on the opening. Some are more strictly defined than others; e.g. a game is really only a "Ruy Lopez" if it reached the position after 1.e4 e5 2.Nf3 Nc6 3.Bb5, but lots of different lines where white plays an early d2-d4 and black's ...c7-c5 is answered by d4-d5 are called "Benoni".

Some variations have a well-known name on move 12-ish (like the Soltis variation in the Dragon), whereas a major line used in world championship matches like 1.Nf3 d5 2.g3 g6 doesn't even have a real name at all.

There's really no logic to it, it's a bunch a historical accidents and traditions.

But these are only the **names** of openings. They are useful when talking to somebody about your game, or when you need a title for your new book or you are looking for a book, and for nothing else.

They are completely unrelated to how much a given player knows about some opening. Especially opening books often start *from* some named position.
> 3 votes

# Answer
https://en.wikipedia.org/wiki/List\_of\_chess\_openings has what you want.

> And after such identifying moves, can we we say that such opening is already completed and the player is on his own for the development of his pieces

Openings certainly don't "complete" like that. In fact, ECO openings only give you the head start. Whether a player is on his own depends on the skills. For example, grandmasters certainly understands better chess than the wikipedia can give.
> 2 votes

---
Tags: opening, learning
---


# Question
Title: Is this position with KRP against KBP a draw?
I encountered the following position with White to move.

```
[FEN "6R1/8/3k4/pK6/Pb6/8/8/8 w - - 45 83"]

```

I see no way for White to win, but am not completely sure. Is it known to be a draw? More generally, is the result for all such positions with head-to-head pawns and rook against bishop known?

# Answer
> 10 votes
This endgame is indeed a draw. You can check positions with 7 or fewer pieces in the Sygyzy tablebases to see if they are a win, a loss, or a draw. If you want the depth to mate for 6 pieces or fewer, use the Shredder database

Given the context, I suppose you would like to know **why** this is a draw. If White was trying to win, the best option is to take Black’s pawn. Black’s bishop is stuck defending it. If the pawn falls, Black falls with it. White can and will win the pawn.

```
[FEN "6R1/8/3k4/pK6/Pb6/8/8/8 w - - 0 1"]

1. Ra8 Kd5 2. Rxa5 Bxa5 3. Kxa5 Kc5

```

The clutch is doing soh leaves White with a major problem. The pawn endgame is a draw! Due to having a rook pawn, White will either be stalemated by the Black king, or Black will get in front of the pawn and be stalemated by White.

---

```
[Title "White is stalemated"]
[FEN "8/8/8/K1k5/P7/8/8/8 w - - 0 1"]

1. Ka6 Kc6 2. a5 Kc7 3. Ka7 Kc8 4. a6 Kc7 5. Ka8 Kc8 6. a7 Kc7

```

---

```
[Title "Black is stalemated"]
[FEN "8/8/8/K1k5/P7/8/8/8 w - - 0 1"]

1. Ka6 Kc6 2. Ka5 Kb7 3. Kb5 Ka7 4. a5 Kb7 5. a6+ Ka7 6. Ka5 Kb8 7. Kb6 Ka8 8. a7

```

---

If White does not target g the Black pawn, BBlack will merely wait it out. They will just shuffle their bishop around to keep protecting their pawn. The Black king will move around such that the pawn endgame will remain drawn. Eventually, there will be a draw via the 50-move rule or threefold repetition.

For all situations with head-to-head pawns, it seems that most will be won. Moving your position one file over move creates gives a win for White. Therefore, it seems to me that the only drawn positions are ones with rook pawns and a close enough Black king. In other words, there are very few of them.

```
[FEN "7R/8/4k3/1pK5/1Pb5/8/8/8 w - - 0 1"]

1. Rb8 Bb3 2. Rxb5 Kd7 3. Rb7+ Kc8 4. Re7 Bd1 5. b5 Bf3 6. Rf7 Be4 7. Kb6 Bg6 8. Re7 Kd8 9. Re5 Bc2 10. Kc6 Bb3 11. b6 Ba4+ 12. Kd6 Kc8 13. Re7 Kb8 14. b7 Be8 15. Kc5 Ka7 16. Rxe8 Kxb7 17. Re7+ Kc8 18. Kc6 Kb8 19. Rf7 Ka8 20. Kb6 Kb8 21. Rf8#

```

# Answer
> 7 votes
This particular position is a draw; since it's a 6-man endgame, you can use e.g. Shredder's database.

However, not all positions like this (with blocked rook pawns) are drawn. A famous one is Timman vs. Velimirovic, Rio de Janeiro, 1979. That game was adjourned three(!) times, giving both players plenty of opportunity to analyze it. In the end, Timman managed to win it, just before the 50-move rule kicked in. The main idea is to cut off the black king on the kingside (by mating threats and/or attacking the bishop), then sacrifice the rook for the bishop and the pawn and use the king to block the black king from reaching the promotion square.

Again, that is not possible from your starting position, since the Black king is already close to a8, but with the Black king on f4, it is a win for White:

```
[FEN "6R1/8/8/pK6/Pb3k2/8/8/8 w - - 45 83"]

1. Ra8 Ke5 2. Rxa5 Bxa5 3. Kxa5 Kd6 4. Kb6 Kd7 5. Kb7

```

The same procedure (sacrificing the rook for the bishop and pawn) **always** wins if the pawns are *not* rook pawns. It's relatively easy for White to reach one of the key squares of the last pawn after the exchange, except if you time it so badly that the Black king can take opposition. But it's rather simple to drive the Black king far away enough.

# Answer
> 4 votes
I once drew a game by heading to this type of position. A great benefit of knowing endings is knowing when to head into the ending and what positions to aim for. I am black below in a tense game with blunders on both sides.

```
[Result "1/2-1/2"]
[Termination "Game drawn by agreement"]
[TimeControl "1/259200"]
[FEN ""]

1.c4 Nf6 2.d4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.d5 a5 8.h3 Na6
9.Bg5 h6 10.Be3 Nh5 11.Qd2 Nf4 12.Bxf4 exf4 13.Qxf4 Nc5 14.O-O-O Re8
15.Nd4 Bf6 16.h4 g5 17.Qe3 gxh4 18.g3 Qe7 19.gxh4 Bg7 20.Rdg1 Kh8
21.Bh5 Qe5 22.Bxf7 Re7 23.Nf3 Qf6 24.Bg6 a4 25.e5 Qf8 26.e6 a3
27.b3 Qf6 28.Kc2 c6 29.Nd2 cxd5 30.cxd5 Nxe6 31.Nde4 Nd4+ 32.Kb1 Bf5
33.Bxf5 Nxf5 34.Nxf6 Nxe3 35.Rg6 Rf8 36.fxe3 Rxf6 37.Rxf6 Bxf6
38.Nb5 Rxe3 39.Nxd6 Rd3 40.Kc2 Rxd5 41.Nxb7 Be7 42.Re1 Bxh4 43.Re6 Kg7
44.b4 Bg5 45.Kb3 Bc1 46.Re1 Bb2 47.Na5 Rd3+ 48.Ka4 Rd4 49.Nc6 Rc4
50.Ne5 Rd4  51.Rh1 Bc3 52.Nc6 Rc4 53.Kb5 Rxc6 54.Kxc6 Bxb4 55.Kd5 Kg6
56.Rh3 Kg5 57.Ke5 h5 58.Rg3+ Kh4 59.Rb3 Bf8 60.Kf5 Be7 61.Rb7 Bd6
62.Rh7 Bc5  63.Kg6 Kg4 64.Rxh5 Bd4 65.Ra5 Bb2 66.Rf5 Bc1 67.Kf6 Bb2+
68.Ke6 Bc3 69.Rf7 Kg5 70.Kd5 Bb2 71.Kc4 Kg6 72.Rf1 Kg5 73.Kb4 Kg6
74.Rf3 Kg5 75.Rxa3 Bxa3+ 76.Kxa3 Kf5 77.Kb4 Ke6 78.Kb5 Kd7 79.a4 Kc7 1/2-1/2

```

---
Tags: endgame, rook-and-minor-endgame
---


# Question
Title: What effects would being able to capture while castling have?
Capturing an enemy piece while castling has been illegal for many decades, and the concept has been solidified in chess history.

But what effects would it have if it were allowed? First, some ground rules.

1). Captures may only take place on the squares where the king and rook land, for obvious reasons. As such, castling cannot be done of an enemy is on b2/b8.

2). The king and rook are capable of both capturing when castling, since it just makes sense that they should be able to.

3). Castling with capture if the king is in check is allowed, as it is merely a complicated capture, one of the 3 ways to get out of check. This is not castling out of check in my opinion. The king may also castle if their square is occupied by a checking piece, as that is not castling into check, but a long-range capture for the king.

For example, to bring everything together, castling in this position is perfectly legal given that the king and rook have not moved before. The king is moving onto a checking piece's square, the checking piece is being taken by the rook, and both the king and rook are capturing on their landing squares.

```
[FEN "8/8/8/8/8/8/8/R1qqK2k w - - 0 1"]

1. O-O-O+ {White takes both queens with check, thereby winning the game!}

```

Note-in this position, the Black queen reached their current squares via promotion and/or capture.

---

What effect, in endgames and middlegames in particular, would this have on chess, if capturing while castling was legal? What kinds of tactics would become obsolete, and what new ones could arise? To keep them question limited, only a few examples are needed for a sufficient answer. Good, solid examples in which the differences between present rules and these new ones determine, down to the bone, who wins would be appreciated.

Lastly, does anyone know of a joke problem that has been created using this concept?

# Answer
> 2 votes
Not much would be affected, as user @user1583209 noted in a new deleted comment: “ I don't think this would change much. By the time an enemy piece entered that far into your camp usually you would typically have castled already or lost castling rights anyway.”

However, there are at least a few positions in the opening lines that would be influenced at the least. For example, in this line of play Blacks gains a small advantage, at the least, by preventing White from castling kindside.

```
[FEN ""]

1. e4 b6 2. Nf3 c5 3. d4 Ba6 4. d5 Bxf1 5. Kxf1

```

But if capturing while castling were allowed, White will be able to castle whilst capturing the bishop, retaining the advantage, not having to take the time to manually castle.

Additionally, as @Chessanator noted in a comment, the Benko Gambit would be the most affeted opening due to having a similar motive in my example.

---
Tags: theory, castling
---


# Question
Title: Are there any repeated games between GMs?
I know there are almost an infinite numbers of games in chess, which is actually near 10^40.

But had a thought; in the games played between grandmasters, they usually they know what the best move is, so I guess the possible number of games is significantly reduced in that scenario.

Is possible to have two repeated games? Or are the chances for this too low, even with two GMs always making some of the best moves?

# Answer
It depends on what you mean by "repeat games", but even in the strictest sense of the word, repeat games have certainly happened. Here's an example of a completely repeated game:

```
[FEN ""]
[White "Liviu Dieter Nisipeanu"]
[Black "Gata Kamsky"]
 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.c3 Nf6 5.d4 exd4 6.cxd4 Bb4+ 7.Bd2 Bxd2+ 8.Nbxd2 d5 9.exd5 Nxd5 10.Qb3 Na5 11.Qa4+ Nc6 12.Qb3 Na5 13.Qa4+ Nc6 14.Qb3 Na5 15.Qa4+ Nc6 16.Qb3

```

This is a well-known draw, and as Chessbase put it, there've been at least 75 games that ended this way. Still, you can't fault the players: Nisipeanu (who had White) had lost his first two games in the tournament, while Kamsky had the Black pieces and one can't ask for more than a draw with Black.

If you're thinking of "repeated" until a decisive result, then opening traps can easily yield repeated games. Here's a famous example:

```
[FEN ""]
 1.d4 d5 2. c4 dxc4 3. Nf3 c6 4. e3 Be6 5. Ng5?? Qa5+

```

Black wins since the knight on g5 is lost. A list of victims of this trap is given here.

Here's another record that might be of interest. Although the game wasn't repeated in its entirety, it was repeated up to the point where a human player might have resigned. In game 64 of the superfinal of the 16th TCEC season, between top engines Stockfish & AllieStein, the engines followed a known game for 39 moves. The original game happened in 2018, between Exxon (Toltec 4 Pro)-Attakinski (Raubfisch ME262\_GTZ). Playing out the position after the book line ended was rather academic, since Black is completely lost.

```
[FEN ""]
[White "Stockfish"]
[Black "AllieStein"]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. e5 Nfd7 5. f4 c5 6. Nf3 Nc6 7. Be3 Qb6 8. Na4 Qa5+ 9. c3 Nxd4 10. Nxd4 cxd4 11. b4 Qc7 12. Bxd4 Be7 13. Bd3 Nb8 14. O-O b6 15. Rc1 Nc6 16. Bf2 O-O 17. a3 Bb7 18. c4 dxc4 19. Rxc4 b5 20. Rc3 bxa4 21. b5 Rfc8 22. bxc6 Bxc6 23. Bxh7+ Kxh7 24. Qh5+ Kg8 25. f5 Qxe5 26. Rh3 g6 27. Qh7+ Kf8 28. fxe6 Qg7 29. Be3 Qxh7 30. Rxh7 Kg8 31. Rfxf7 Bf6 32. Rh6 Bb2 33. Rxg6+ Kh8 34. e7 Be8 35. Rh6+ Kg8 36. Rf8+ Kg7 37. Rhh8 Kg6 38. Rhg8+ Kh7 39. g4 Rcb8 40. g5 Be5 41. Bc5 Bg6 42. Rd8 a6 43. Kf2 Bf7 44. h3 Bg6 45. Kf3 a5 1-0

```
> 5 votes

---
Tags: grandmaster, master-games
---


title: Openings that reach endgames?

text:
# Question
Title: Openings that reach endgames?
I'm looking for some openings for white and black that have a high probability of trading queens early on without being significantly worse. Does anyone know any openings that fit this criteria?

# Answer
There's a "drawing line" in the Petrov Defense for White:

```
[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Qe2 Qe7 {Black has to play this or 6. d3 wins a piece} 6. d3 Nf6 7. Qxe7+

```

Playing 7. Qxe7+ loses White's opening half-tempo, but queens are off, and if that's what White wants he's gotten it. Not playing Qxe7+ can still lead to a queen trade, until either side decides to block the e-file with minors.

The Berlin Defense is another well-known opening with early queen trade:

```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5.d4 Nd6 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8

```

This opening has gained a reputation for drawishness at GM level.
> 5 votes

# Answer
White:

Exchange Spanish with an early d4

1.d4 King's Indian Exchange Variation

Black:

Pirc Defence 1.e4 d6 2.d4 Nf6 3.Nc3 e5 4.dxe5 dxe5 - I actually think this is close to equal for Black. (4.Nf3 is usually played.)

Berlin Defence

Nimzo-Indian 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 O-O 5.a3 Bxc3+ 6.Qxc3 b6 7.Bg5 Bb7 8.f3 h6 9.Bh4 d5 10.e3 Nbd7 11.cxd5 Nxd5 12.Bxd8 Nxc3 13.Bh4 Nd5

If you want to look for a highly effective repertoire for white based on early simplifications, I would say Oleg Krivonosov's (olegas) games on ICC are very underrated. Some other players are pretty good at sidelines, but these may not trade pieces very often, such as Igor Glek and Michael Adams.
> 1 votes

---
Tags: opening, endgame, queens, captures, trading
---


# Question
Title: Breadth-first search vs Depth first search in knowledge-based chess engines
I would like to learn about the difference between depth-first and breadth-first search in knowledge-based chess engines (that, of course, excludes alpha-zero). The difference isn't that clear-cut, but, to my knowledge, some engines prefer to go deeper than explore more options per move. It seems that depth-first search, as it is used in Stockfish, has prevailed for now, but I don't necessarily find that obvious. Can anyone point me to research which has been done in this area?

# Answer
Strength in chess engines depends on speed and speed depends on how strongly you can prune the tree. That is, how many nodes you can discard without degrading the accuracy of your search result.

In principle you might be able to visit the same nodes using either BFS or DFS, so a priori it is not clear which would be better prunable i.e. faster.

In chess, however, DFS is better prunable because one strong countermove is enough to invalidate a move. Therefore, the value of a move depends more strongly on a small set of next countermoves and the value of these countermoves on a small set of next moves etc. So, Min-Max-Search naturally lends itself to better pruning with DFS.
> 5 votes

# Answer
There is no need for research. Breadth-first, by definition needs to traverse all nodes at a level before going to the next. It just doesn't work for chess, where the number of positions is too many and most of the positions are just stupid (e.g. dropping a queen). Chess engines always use deep-first.
> 3 votes

# Answer
One important point to consider is that **BFS has a hugely higher space complexity than DFS**.

Notation:

* b = branching factor = number of moves per step, about 31 in chess
* d = minimum depth of tree till optimal solution (e.g. 10 if checkmate in 10 turns is possible)
* m = maximum depth of tree (e.g. 150 moves till draw)

**Space complexity of BFS: O(b^d)**

**Space complexity of DFS: O(b * m)**

Assuming that a position with b=31, d=10 and m=150 is evaluated and each node needs 24 Bytes of space, BFS would need about 20 **Peta**byte of space and DFS only 111 KB, making BFS infeasible. Also keep in mind that modern CPUs only have a few MB of cache (e.g. 16 MB for the i9-9900KS), so they could not even fit all nodes of BFS at the depth of d=4 (22MB).

With strong pruning (i.e. throw away very bad moves), the branching factor can be reduced to perhaps 5-10 good moves per step, but this does not solve the exponential space complexity of BFS.
> 3 votes

# Answer
In addition to the great accepted answer, I'll point out that engines do differ in the amount of breadth/depth they analyze, even though all of them do use depth first search because of alpha beta search (something you should research if you want to learn more, as all traditional engines use it) being much better optimized for it.

For example, Stockfish is very well known for aggressively getting rid of moves it has to consider through various pruning techniques, so it can consider the best few moves to extremely great depths because it doesn't need to calculate as many positions.
> 2 votes

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


title: Software-based training on Linux

text:
# Question
Title: Software-based training on Linux
10 years ago I used to learn from an old version of Fritz on DVD. It was great. It had a teaching move while you played full games and it also had automated curriculum to teach you openings, endings, and tactics.

At this point in my life I've fully rejected all Windows and MacOS operating systems in favor of Linux. I'd like to have a chess learning experience like I did with Fritz, though.

I've signed up for Chessbase/Fritz online, but it doesn't seem to have any of the many learning features that I had a decade ago. Do I have any other good options?

I'm looking for a richer learning experience than just an engine analyzing my games post-hoc.

# Answer
Have you taken a look at lichess.org ? It has a solid web interface, Android/iPhone applications, plenty of chess games/variants, analysis move, there are a few trainings, starting from the basics and ending with pretty advanced stuff, finally there are puzzles taken from the actual chess games, where you have to win the game someone won (or lost) before.
> 3 votes

# Answer
You can have a look at Lucas Chess. There's a version for both Linux and Windows. (I use the windows version with wine and no performance problems). There's a lot of modes and resources for studying in this software.
> 1 votes

---
Tags: learning, software, training
---


title: Lichess' Stockfish's tuning

text:
# Question
Title: Lichess' Stockfish's tuning
I remark that whatever the level of the Lichess' Stockfish I choose it plays in average at the same speed. How could I tune my Stockfish (the one I use in Fritz or Arena) to achieve the same with the same performance ?

# Answer
The settings used for the Stockfish levels on lichess can be found at https://github.com/niklasf/fishnet/blob/53e218bd184554265748513f85d19e601f18c310/fishnet.py#L117-L119:

```
LVL_SKILL = [0, 3, 6, 10, 14, 16, 18, 20]
LVL_MOVETIMES = [50, 100, 150, 200, 300, 400, 500, 1000]
LVL_DEPTHS = [1, 1, 2, 3, 5, 8, 13, 22]

```

where `LVL_SKILL` refers to the `Skill Level` UCI option in Stockfish, `LVL_MOVETIMES` to the maximum move time in milliseconds, and `LVL_DEPTHS` to the maximum depth for each of the eight levels.

The move time and depth might not be easy to set in a local GUI, but you can simply use the `Skill Level` option to adjust playing strength where 20 means best play and 0 is the lowest available level for Stockfish.
> 5 votes

---
Tags: stockfish, lichess
---


# Question
Title: Is the game done if your only movement is getting out of check?
If I play as White and use my queen to check Black on every move, and Black can only move their king to get out of the check, can I win the game? White could move something else, but they decide to check on every move.

This happened years ago when I was new to the game in a tournament, and the referee gave me the win as it was not checkmate, but my opponent only had a king and two pawns left. Was that my win?

# Answer
No, this is not a win.

What you describe is called perpetual check and according to the rules of chess it results in a draw.
> 6 votes

# Answer
> Is the game done if your only movement is getting out of check?

No. By rule, your *only* legal move when in check is to get out of check if you can. If you cannot, the game is over, as it is checkmate.

> If I play as White and use my queen to check Black on every move, and Black can only move their king to get out of the check, can I win the game? White could move something else, but they decide to check on every move.

Initially, the game isn't over just because you keep putting the other player in check. However, if this goes on long enough without any captures or pawn moves, your opponent could invoke the 50 move rule. If that doesn't happen, the tournament director (TD) could eventually invoke the 75 move rule (referenced at the same Wikipedia link as the 50 move rule). In either case, the game would be a draw. Also, before you invoke one of those rules, you may achieve a threefold repetition, which is also a draw.

> This happened years ago when I was new to the game in a tournament, and the referee gave me the win as it was not checkmate, but my opponent only had a king and two pawns left. Was that my win?

Taking the last first, yes, it was your win. However, instead of a win on the board, the TD gave you the win by adjudication, because in their opinion you would have gotten there eventually. There may have been a time constraint to be met - perhaps the next round needed to start to keep the event on schedule, or - if it was the last round - the room needed to be vacated for another event.
> 1 votes

---
Tags: rules, draw, check
---


# Question
Title: How to proceed in this endgame position?
```
[FEN "3k4/ppp3pp/1b6/8/PP6/4BpP1/5P1P/6K1 b - - 1 24"]

```

This position is evaluated -4 but i cant find any plans for Black and lost. What should have been my strategy from this position ?

This is the full game :

```
[Event "Rated Rapid game"]
[Site "https://lichess.org/xxLijzuK"]
[Date "2020.04.08"]
[Round "-"]
[White "CorsaireBouritos"]
[Black "AKP2002"]
[Result "1-0"]
[UTCDate "2020.04.08"]
[UTCTime "06:59:51"]
[WhiteElo "1214"]
[BlackElo "1228"]
[WhiteRatingDiff "+6"]
[BlackRatingDiff "-6"]
[Variant "Standard"]
[TimeControl "600+0"]
[ECO "B02"]
[Opening "Alekhine Defense: Scandinavian Variation"]
[Termination "Normal"]
[Annotator "lichess.org"]
[FEN ""]

1. e4 Nf6 2. Nc3?! { (0.63 → 0.00) Inaccuracy. e5 was best. } (2. e5 Nd5 3. c4 Nb6 4. d4 d6 5. f4 g6 6. Nc3 Bg7) 2... d5 { B02 Alekhine Defense: Scandinavian Variation } 3. Nxd5 Nxd5 4. exd5 Qxd5 5. c3?! { (0.08 → -0.48) Inaccuracy. d4 was best. } (5. d4 Nc6 6. Be3 e5 7. Nf3 exd4 8. Nxd4 Nxd4 9. Qxd4 Qxd4) 5... Nc6 6. d4?! { (0.00 → -0.75) Inaccuracy. Qf3 was best. } (6. Qf3 Be6 7. d4 O-O-O 8. Be2 h5 9. Qxd5 Bxd5 10. Nf3 h4) 6... e5 7. Nf3 e4?? { (-0.94 → 0.70) Blunder. exd4 was best. } (7... exd4 8. Nxd4 Nxd4 9. Be3 Bc5 10. Bxd4 Bxd4 11. Qxd4 Qxd4 12. cxd4) 8. Ng5? { (0.70 → -0.42) Mistake. Nd2 was best. } (8. Nd2 Be7 9. Nc4 O-O 10. Bf4 Qd8 11. d5 Nb8 12. Be2 Nd7) 8... Be6?? { (-0.42 → 1.92) Blunder. h6 was best. } (8... h6 9. Nh3) 9. Nxe6 fxe6 10. g3?? { (1.71 → 0.13) Blunder. Qb3 was best. } (10. Qb3 Qxb3) 10... e5?! { (0.13 → 0.97) Inaccuracy. e3 was best. } (10... e3 11. f3) 11. Bg2 exd4 12. cxd4?? { (1.01 → -1.30) Blunder. Qg4 was best. } (12. Qg4) 12... Nxd4?? { (-1.30 → 0.36) Blunder. Bb4+ was best. } (12... Bb4+ 13. Bd2) 13. O-O O-O-O 14. Re1?? { (0.28 → -1.35) Blunder. Qg4+ was best. } (14. Qg4+ Kb8) 14... Nf3+ 15. Bxf3 Qxd1?? { (-1.29 → 5.46) Blunder. exf3 was best. } (15... exf3 16. Qa4 Bc5 17. Be3 Bxe3 18. Rxe3 Kb8 19. Qg4 Qxa2 20. Ra3 Qd5 21. Qxf3 a6 22. Qxd5) 16. Rxd1?? { (5.46 → -0.76) Blunder. Bxd1 was best. } (16. Bxd1) 16... exf3 17. Rxd8+ Kxd8 18. Bf4 Bb4?! { (-1.27 → -0.58) Inaccuracy. Bc5 was best. } (18... Bc5) 19. Rd1+ Kc8 20. a3 Ba5 21. b4 Bb6 22. a4? { (-0.94 → -2.07) Mistake. Rd3 was best. } (22. Rd3 Rf8 23. h4 h6 24. Kf1 a5 25. h5 Rf5 26. Rxf3 Rxh5 27. Bd2 Rd5 28. Ke2 Re5+) 22... Rd8 23. Rxd8+?! { (-1.57 → -2.63) Inaccuracy. Rc1 was best. } (23. Rc1) 23... Kxd8 24. Be3?! { (-2.54 → -3.85) Inaccuracy. h4 was best. } (24. h4 Kd7 25. Be5 a5 26. bxa5 Bxa5 27. Bxg7 Ke6 28. h5 c5 29. Kh2 c4 30. Kh3 Kd5) 24... Bxe3 25. fxe3 g5 26. g4?! { (-2.39 → -3.53) Inaccuracy. h3 was best. } (26. h3 h5) 26... b6?? { (-3.53 → 0.00) Blunder. Kd7 was best. } (26... Kd7 27. Kf2 c5 28. bxc5 Kc6 29. a5 Kxc5 30. Kxf3 b6 31. a6 Kc4 32. Ke4 b5 33. Kf3) 27. b5?? { (0.00 → -2.46) Blunder. Kf2 was best. } (27. Kf2 Ke7 28. Kxf3 c6 29. Ke4 Kf6 30. Kd3 Ke5 31. e4 h6 32. h3 Ke6 33. Kc3 Ke5) 27... Kd7? { (-2.46 → -1.22) Mistake. Ke7 was best. } (27... Ke7 28. Kf2 c5 29. Kxf3 Kd6 30. Ke2 Kd5 31. Kd3 Ke5 32. Kd2 Ke4 33. Ke2 c4 34. Kd2) 28. Kf2 Kd6 29. Kxf3 Kc5?? { (-3.08 → 0.00) Blunder. c6 was best. } (29... c6) 30. e4?? { (0.00 → -2.66) Blunder. Ke4 was best. } (30. Ke4 c6 31. bxc6 Kxc6 32. Ke5 a6 33. e4 b5 34. axb5+ axb5 35. Kf6 Kd7 36. Kf7 Kd6) 30... Kb4?? { (-2.66 → 12.85) Blunder. Kd4 was best. } (30... Kd4 31. h3) 31. e5 Kc5 32. Ke4 h5 33. gxh5 g4 34. e6 Kd6 35. Kf5 Ke7?! { (25.19 → Mate in 9) Checkmate is now unavoidable. Kc5 was best. } (35... Kc5 36. e7) 36. h6 Kf8 37. Kf6 Kg8 38. e7 Kh7 39. Kg5 { Black resigns. } 1-0

```

# Answer
This is a very common kind of endgame, where you have a pawn majority on one side and fight against a single pawn in the center. Winning this is not difficult, but let's first look at your game...

You

* fixed the position of the queenside pawns by playing b6 (to which white cleverly replied b5
* ran with your king towards the queenside

Basically you should do the opposite:

* keep your king in the center close to the white e-pawn (say around e5, d5, e4 or c4), which white cannot advance
* try to create a passed pawn on the queenside: for this you want to start with a6 or c6, not b6.

The idea then is to have that a-b-c passed pawn run, forcing the white king away from the protection of the kingside pawns

One possible line with comments....

```
[FEN "3k4/ppp3pp/1b6/8/PP6/4BpP1/5P1P/6K1 b - - 1 1"]

1... Bxe3 { Perhaps not the computer's first choice but a decent practical human decision to turn it into a clearly won pawn endgame. Could perhpas have delayed this exchange to gain an extra tempo (for centralizing the king) since white does not have any good moves. } (1... a5 { Prevents white from playing a5. Objectively the strongest move in the position. The main idea is to keep the white king out of play for as long as possible. } 2. bxa5 (2. b5 Kd7 3. Kf1 Kd6 4. Ke1 (4. Bd2 Kd5 { and white does not get anywhere as the king is bound to the protection of the f2 pawn, black can just collect the a and b pawns or promote the c pawn as he wishes. }) 4... Bxe3 { now is the time to exchange because black will keep the f3 pawn } 5. fxe3 Kd5 6. Kf2 Ke4 { followed by c5-c4-c3-c2-c1Q 0-1 }) 2... Bxa5 { The white king's path to freedom via f1 e1 is now blocked. Black is basically playing king+bishop+pawn vs a single bishop. } 3. h4 { trying to activate the king via h2 } 3... Kd7 { centralizing the king } 4. Kh2 Kc6 5. g4 Kd5 6. Kg3 Ke4 7. Bc5 (7. g5 g6 { the white king has no way to escape and black just pushes the c pawn to c1 }) 7... b6 8. Bf8 g6 { and black will just push the c pawn to c1. }) 2. fxe3 g5 { threatening to create a protected passed pawn on f3. } 3. g4 Kd7 4. Kf2 Ke6 5. Kxf3 Kd5 { First goal achieved: King is centralized. Note that white can never play e4 since after Kd4 white will eventually run out of moves and will have to move the king from the protection of the e pawn. } 6. b5 c6 { or a6 or c5 all will create a passed pawn for black } 7. bxc6 { basically forced because otherwise black would end up with one vs zero pawns on the queenside, which would make his task even easier } 7... bxc6 { Second goal achieved: black has a passed pawn } 8. a5 c5 9. Ke2 Kc4! { Aiminig for the a5 pawn, while keeping an eye on the e3 pawn (which would still be lost after e4 Kd4). Also the black king is threatening to get to d3 after which white would also be lost. } 10. Kd2 { basically forced, because black was also threatening Kc3 after which he'd get to d3 when white runs out of pawn moves } 10... a6 11. Kc2 Kb4 12. Kd3 Kxa5 { Again this is the more human decision. Black could also go for pawn promotion with Kb3 (followed by c4...). It is important to realize that black can catch the e pawn (rule of the square). Also it helps that the lone white king is lost against the a and c pawn (even without the black king's support). } 13. Kc4 Kb6 14. e4 a5 15. Kd5 (15. e5 a4 16. e6 Kc6 17. e7 Kd7 { and the white king is lost against the a and c pawns }) 15... a4 { I am faster than you. Needs to count. } 16. e5 a3 17. e6 a2 18. e7 a1=Q 19. e8=Q Qd4+ 20. Ke6 Qe3+ { and black trades queens and will get a new queen soon on c1. } *

```
> 13 votes

# Answer
I think you should avoid taking on `e3`, even though it is objectively winning, this gives your opponent a passed pawn on e-file and exposes your f3-pawn (which is a big headache for white), this complicates the game.

If you don't take on `e3` yourself, you opponent can force you with `a5`, is there a way to stop that? Yes, there is: play `1...a5` yourself, if `2.bxa5 Bxa5`, just march you king to `e4` and push your pawns on the queen side. For anything else white pawns on the queen side will be too weak, you can just march your king over and take them.
> 7 votes

---
Tags: endgame, pawn-structure, pawn-endgame
---


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

```

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

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

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

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

# Answer
> 10 votes
There's a 12-page chapter on this position in Cristoph Wisneski's "Play 1...Nc6!: A complete chess opening repertoire for Black." In that book it's reached via 1.e4 Nc6, 2.d4 d5, 3.Nc3 e6. More generally you're probably more likely to see this discussed in books on the Nimzowitsch defense (with d5, not e5) rather than French defense books.

# Answer
> 7 votes
There's also a chapter on it in "Dangerous Weapons: French" by John Watson from Everyman (2007)

---
Tags: opening, french-defense
---


title: Train Leela Chess against myself

text:
# Question
Title: Train Leela Chess against myself
Is it possible to play against a "virgin" Leela Chess engine to see how many games it takes it to beat me? That is, can I train Leela Chess by playing against it myself?

# Answer
> 9 votes
Not an expert but you can play against a "virgin" Leela by using one of the younger nets. For example in the first Leela test (the so-called training run) the strongest net was 11248. If you play against, e.g., net 00010, it'll be much weaker.

However, you can't train Leela by playing against it. You can play against the trained product, but you can't train Leela yourself. That's because Leela is supposed to learn entirely by self-play (that's why its full name is Leela Chess Zero - "Zero" for zero human knowledge).

# Answer
> 5 votes
Yes, you could in principle set up Leela such that it learns by playing against you. It would require some programming skills and a lot of time to play games.

Currently Leela has been trained on 300.000.000 games. You should expect to have to play at least a couple of thousand games against it to see an improvement.

Also, Leela doesn't learn anything if it always loses. So you either can't start from zero, or you'd have to massively handicap yourself such that you regularly lose even against the initial random play.

---
Tags: training, leela, windows
---


# Question
Title: Can we play to reach study like positions?
I am talking about a field called "Chess Study". A typical chess study is very complex, and even computers make mistakes in solving them.

So, can we play some variation which can result in such positions ?

See for example this very famous study and its commentary:

Solution to a truly remarkable study

Grandmasters and Engines Couldn't Solve This Puzzle. Then Came The Magician

# Answer
> 2 votes
> So, can we play some variation which can result in such positions ?

If a study is legal, so can be reached from the starting position by a series of legal moves, then the answer to your question is trivially "Yes".

Chess players shouldn't really collude before the game to decide the outcome but when siblings or partners play each other they sometimes play an agreed sequence of moves which leads to a forced draw.

In the same way two players could work out the moves required to reach a particular study position, agree to play them and then play them.

---
Tags: study
---


# Question
Title: How can I convert screenshot capture into FEN to analyse on Windows 10+?
I want to analyze position presented on meeting, web page or video but problem is that I have not FEN to start such analysis. It need manual work to do it.

I want to capture screenshot than convert it into FEN. How can I do it on Windows 10+? (not create image/scan than process it with external tools which is not doing screenshots - I know how to do it in such way.)

On Windows I can use Shift+Window+S to capture region than save to image or to clipboard. Is anybody using some software or tool to do it?

I can write such software with use deep learning but it takes time and maybe it is not need to invent wheel again.

# Answer
This will do it. https://chessvision.ai. There is also the Chessify app on the ios store where you can take pictures of chessboards and import the position.
> 6 votes

# Answer
https://www.ocf.berkeley.edu/~abhishek/putz/ Lost two piece from scan

http://www.chessgrabber.nicolaas.net/ Lost one piece, added one piece, and replaced two pieces.

https://play.google.com/store/apps/details?id=com.fimetech.chessfimee Claims to be 98% accurate.
> 4 votes

---
Tags: analysis, software, fen
---


# Question
Title: How close was Seirawan to challenging Kasparov?
Growing up in the '80's in the Pacific Northwest (USA), my chess hero naturally was Yasser Seirawan. He was the first top-class GM to emerge from the USA since Fischer and our country's best hope to break the Soviet headlock on world chess. Our hopes at the time seemed reasonable - he twice made the Candidates Matches. Sadly, after the fall of the Iron Curtain the chess world fell into general chaos, and my understanding is that Yasser spent what should have been his peak competitive years focused on simply making a living in a difficult chess economy. He famously beat the newly minted world champion, Kasparov, in the '86 Olympiad, but never had a chance at the title. He semi-retired from competitive chess around the turn of the century, but has returned to competition on occasion and turned in some very strong results. In 2011 he earned a silver medal in the World Team Championships, representing the USA, with a 2773 performance rating. (To me, that seems a ridiculous result!)

My question to the historians of the game: Did Seirawan have the potential to challenge Kasparov, but was held back by his inability to focus entirely on chess in that chaotic era? Or am I just making excuses for my hero, and I should be content with Seirawan's considerable achievements and the salutary impact that he has had on American (and world-wide) chess.

# Answer
There are games on record between the two:

```

[Title "Yasser Seirawan vs Garry Kasparov (1986)"]
[Event "Dubai"]
[Site "Dubai"]
[Date "1986.11.23"]
[EventDate "?"]
[Round "8"]
[Result "1-0"]
[White "Yasser Seirawan"]
[Black "Garry Kasparov"]
[ECO "D91"]
[PlyCount "123"]
[FEN ""]

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.Bg5 Ne4 6.cxd5 Nxg5
7.Nxg5 e6 8.Nf3 exd5 9.b4 Qd6 10.a3 O-O 11.e3 c6 12.Be2 Bf5
13.O-O Nd7 14.Na4 a5 15.Qb3 b5 16.Nc5 a4 17.Qc3 Nb6 18.Nd2
Rae8 19.Rfe1 Re7 20.Bf3 Rfe8 21.g3 Bh3 22.Bg2 Bxg2 23.Kxg2 f5
24.h4 Nc4 25.Nf3 Bf6 26.Re2 Rg7 27.Rh1 Qe7 28.Ree1 h6 29.Qd3
Rf8 30.Nd2 Qe8 31.Nxc4 dxc4 32.Qd1 Re7 33.Ref1 Qf7 34.Qf3 Qd5
35.Qxd5+ cxd5 36.Kf3 Bg7 37.Rd1 Rff7 38.Rd2 Re8 39.Rdd1 Bf8
40.Rdg1 Bg7 41.Rd1 Kf8 42.Rd2 Ke7 43.Rdd1 Kd6 44.Rh2 Kc6
45.Rhh1 Bf8 46.Rd2 Bd6 47.Rdd1 Bxc5 48.dxc5 Re4 49.Rhe1 Rd7
50.Rd4 g5 51.hxg5 hxg5 52.Red1 Rxd4 53.Rxd4 Rh7 54.Ke2 Rh3
55.g4 f4 56.exf4 Rxa3 57.fxg5 Ra2+ 58.Kf3 c3 59.Rd1 d4 60.g6
d3 61.Ke3 Rxf2 62.g7 1-0

```

```

[Title "Garry Kasparov vs Yasser Seirawan (1988): You Come at the King, You Best Not Miss"]
[Event "Thessaloniki ol (09)"]
[Site "Thessaloniki GRE"]
[Date "1988.11.22"]
[EventDate "?"]
[Round "9"]
[Result "1-0"]
[White "Garry Kasparov"]
[Black "Yasser Seirawan"]
[ECO "D21"]
[PlyCount "76"]
[FEN ""]

1.d4 d5 2.Nf3 c5 3.c4 dxc4 4.Nc3 cxd4 5.Qxd4 Qxd4 6.Nxd4 Bd7
7.Ndb5 Na6 8.e4 Nf6 9.f3 Bxb5 10.Nxb5 e5 11.Be3 Bb4+ 12.Kf2
Ke7 13.Bxc4 Rhc8 14.Rac1 Bc5 15.Rhd1 Bxe3+ 16.Kxe3 Ne8 17.Bb3
Rxc1 18.Rxc1 f6 19.a3 Nd6 20.Bd5 Nxb5 21.Bxb7 Nbc7 22.Bxa8
Nxa8 23.Rc8 Nb6 24.Rg8 Kf7 25.Rh8 Nc5 26.Rb8 Ke7 27.b4 Nc4+
28.Ke2 Nd7 29.Rg8 g5 30.a4 a5 31.bxa5 Nxa5 32.Ra8 Nc6 33.a5
Kd6 34.g3 h5 35.h4 gxh4 36.gxh4 Nc5 37.a6 Kc7 38.a7 Nb7 1-0

```

```

[Title "Cup World: Seirawan vs Kasparov (1989)"]
[Event "Cup World"]
[Site "Skelleftea SWE"]
[Date "1989.08.??"]
[EventDate "?"]
[Round "13"]
[Result "1/2-1/2"]
[White "Yasser Seirawan"]
[Black "Garry Kasparov"]
[ECO "E75"]
[PlyCount "85"]
[FEN ""]

1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Be2 O-O 6.Bg5 c5 7.d5 h6
8.Be3 e6 9.Qd2 exd5 10.cxd5 Re8 11.f3 h5 12.a4 a6 13.a5 Nh7
14.Bd1 Nd7 15.Nge2 Ne5 16.b3 Qh4+ 17.Bf2 Qf6 18.Qe3 h4 19.h3
g5 20.O-O Bd7 21.Kh1 Nf8 22.Bg1 Nfg6 23.Bh2 c4 24.Rb1 Rac8
25.Qa7 Nf4 26.bxc4 Nxc4 27.Rxb7 Nd2 28.Rg1 Nxh3 29.e5 Rxe5
30.Rxd7 Nxg1 31.Qxg1 Ree8 32.Rxd6 Qf5 33.Ba4 Qd3 34.Bxe8 Rxe8
35.Rc6 h3 36.Bg3 hxg2 37.Qxg2 Nxf3 38.d6 Re6 39.Qf2 g4 40.Rc8+
Kh7 41.Nf4 Rh6+ 42.Kg2 Ne1+ 43.Kg1 1/2-1/2

```

Yasser Seirawan won the World Junior Chess Championship in 1979 in Skien Norway, a year before Garry Kasparov won it in Dortmund Germany. The two were contemporaneous. Seirawan proceeded to train in Switzerland with Korchnoi following his Junior Chess Championship win.

It's not precisely clear why the two didn't meet up in international competition. In the games they played it seems Seirawan was competitive against Kasparov.

In interview's Seirawan stated publicly that he **doesn't like the FIDE cycle at all** and that he always enjoyed being busy and working on projects (such as writing). Speculating, it could be Seirawan's dedication to editing **Inside Chess magazine** and his dislike for the FIDE cycle may have distracted him away from international competition.

Perhaps only Seirawan knows.
> 8 votes

# Answer
Seirawan explains why he could not be world champion in his book "Chess Duels My Games With The World Champions" In the section titles "World Champion Seirawan?" My summary is that he did not play at world champion strength consistantly enough and that he has interests other than chess.

I highly recommend this book to any Seirawan fan. I also grew up in the pacific northwest in the 80's.
> 6 votes

# Answer
A hero of mine was Karpov. For his ability to make small, seemingly innocuous moves that had the effect of causing imperceptibly small improvements that magically gave him advantages. And in my way of thinking, he was arguably the best defensive player in the world. So I got hold of the book "The Making of a Champion" that gives games from Karpov's career. I was surprised that only two grand masters managed to score 50% against Karpov during Karpov's years at the top (1975-1985). They were Kasparov and Seirawan. That's how impressive Seirawan is at the board. Apologies to those readers who know more and for any inaccuracies.
> 4 votes

---
Tags: history
---


# Question
Title: Is there a way (or tool) to convert games in PGN to notations like the one in the description?
Example:

White: Kd6, Rh6

Black: Kd8

1.?

**Background story:** I'm thinking of creating material for developing the visualization skills of my students. If I can convert easy problems to text notations and ask people to solve them without a chess board, I'm thinking it would be a good exercise for visualization in chess.

# Answer
PGN is for game notation, i.e. the whole game. You can use the FEN notation by creating the position on chessvideos.tv FEN generator site and then use the code to input this into Fritz or your preferred software. Code is on the top right. `3k4/8/3K3R/8/8/8/8/8` is the code for the position you gave.
> 2 votes

# Answer
Just to complete the answer, you can use Fen2Ascii, a little program that converts pasted FEN lines into ASCII formatted text. From its website:

> r1bqk2r/pppp2pp/2n1pn2/5p2/2PP4/5NP1/PP1NPPBP/R2QK2R b KQkq - 0 7
>
> is changed to
>
> W-Ke1,Qd1,Ra1,h1,Bg2,Nd2,f3,Pa2,b2,c4,d4,e2,f2,g3,h2
> B-Ke8,Qd8,Ra8,h8,Bc8,Nc6,f6,Pa7,b7,c7,d7,e6,f5,g7,h7 Black to move.
> 2 votes

---
Tags: database, visualization
---


title: Looking for special chess freeware

text:
# Question
Title: Looking for special chess freeware
I am looking for chess **freeware** that **ideally** has the following facilities, and I am wondering what compromises I'll need to accept. I am also requesting the results of your experiences.

**List Of Needs**

1. It needs to be similar to what the old Window software called **Chessbd** provided. I would like the gui to allow creating a (2nd) **variations** window. The image below illustrates what I am looking for.
2. I would like to be able to **paste** pgn (from the clipboard), so that if I'm examining a game from another source, I don't have to save the pgn to a file and then load the file.
3. I would prefer it if the software allows connection to a separate engine. If not, I want the software to have its own engine.
4. I would prefer it if the software allows a connection to endgame tablebases.
5. I would prefer it if the software allows connection to opening book. If not, I want the software to have its own book.
6. My main PC is Fedora, with Wine, and a secondary PC runs Windows 10 (for other reasons). I use TeamViewer (freeware) for remote access to the secondary pc from the Fedora pc. I therefore would mildly prefer linux compatible or linux-wine compatible.

I appreciate any insights.

---

**Addendum - Arena chess**

First of all, thanks to djnavas for his answer re Arena chess. I just spent some time with Arena and **I was very impressed with it.**

**Unfortunately, unless I am mistaken, it will not do what I want.**

I installed and ran Arena, entered `setup` to enter a position, and then selected `Edit` in the `Navigation Bar`. This allowed me to turn off the engine(s) and make the moves for both sides. After entering a few moves, I selected `Options : Variation Board`. **Unfortunately**, the Variation Board did **not** permit me to **manually add a variation.** Further, the Variation Board did **not** provide **its own pgn-list-window.**

**For those of you who want to experience what I am looking for:**

If you **google** : `Chessbd` you will see the following link: http://www.dfong.com/chessbd/index.html

I just downloaded and started to run slic26v8.exe (i.e. the downloaded Chessbd installer) in Fedora 30, under wine. It looks like the installer was going to work. In another forum, a user responded that slic26v8.exe would not run under Windows 7.

If you can't get the installer to work, can you provide free cloud storage (or any other facility) for me to upload a zip file that looks like it will be less than 10mb? If so, I can upload the zip, you can download-unzip it, then try it.

Of particular note are the Alt-V command that will create an analysis window at any desired point in the mainline pgn, and the Alt-3 command which will append a scrollable pgn sub-window to the analysis window. This way, you can observe the pgn as you are manually trying different variations. These variations are automatically added to the mainline pgn.

When you close the Variations window, you revert back to the main window. Then you can traverse backwards or forwards to a different point in the pgn. When traversing, if you reach a position with a variation, the gui gives you the choice which move to select. At any point while traversing, you can open a new variations window, via Alt-V.

---

**Addendum 2 - ChessPad 2 and Arena Chess**

Thanks again to djnavas for the continued interest.

I tried ChessPad 2 in Fedora 30, via Wine. Invoking its \[Help:Help Topics\] menu option seemed to indicate that Help is not available. Anyway, experimenting, after setting up a position and manually playing a few moves for both sides, **I was unable to leave the display board open and start a second display board.**

Am I missing something here?

> ...I suggest you to start not with a position, but instead with a pgn from the start position...

Questions/comments:

1. Does "start position" refer to the position at the start of an actual game?
2. If not, what does "start position" refer to and how could such a strategy *approach* duplicating the functionality of Chessbd in Arena Chess, or something like it?
3. If so, this would not be practical for examining (for example) a chess endgame study. Getting past that, again, how could such a strategy *approach* duplicating the functionality of Chessbd in Arena Chess, or something like it?

# Answer
Seems like you are interested in a program like Arena. It does what you specified, can open pgn files with one or several games; a copied pgn game can be pasted; can generate diagrams; connect with engines via uci or xboard protocol; manage variations and administer opening books, from the interface.

Also, has versions for Linux and Windows.
> 2 votes

---
Tags: software, pgn, tablebases
---


# Question
Title: How do I keep my bishop pair in this Ruy Lopez line?
I am learning Ruy Lopez. And I always play Ruy Lopez opening while I am playing with the white pieces. I recently played the game with Ruy-Lopez and my moves are

```
[FEN ""]
[StartPly "10"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 b5 5.Bb3 Na5

```

I want to keep my Bishop pair, but if I play like this then my light-square bishop will be lost in 5 moves. So, what is the best move that I can play to save my bishop pair till the end?

# Answer
> 4 votes
In that position, you can't keep your bishop pair if Black wishes to take your Bishop. Acording to Modern Chess Openings, with this variant Black throws away the White Bishop by ceding the initiative in the center. In the recomended continuations, White has an advantage (+/=) and White must proceed to an inmediate attack:

```
[Event "Analysis"]
[Site "Ruy Lopez"]
[Date "2020.04.11"]
[Round "?"]
[White "Player"]
[Black "Oponent"]
[Result "*"]
[FEN ""]
[StartPly "10"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 b5 5.Bb3 Na5 6.O-O d6 7.d4 Nxb3
    ( 7...exd4 8.Nxd4 Bb7 9.Bd2 Nxb3 10.Nxb3 Nf6 11.Re1 Be7 12.Na5 Rb8 $14
    {Smagin - Kupreichik, Minsk 1985.} )
8.axb3 f6 9.Nh4 Ne7 10.f4 exd4 $5
    {It is a possible improvement.}
    ( 10...Bb7 11.d5 c6 12.c4 exf4 $14 {Arnason - Agdestein, Gausdal 1987.
    } )
11.Qxd4 Bb7 12.Nc3 $10
    {1/2-1/2(64) Alves, Lair Valio - Petters Merino, Oscar Augusto / CLEA4
    B07 email, CADAP Email 2000.}
*

```

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


# Question
Title: Database of every possible move in chess
Imagine that there is a chess database of every possible move and position. This database contains all possible moves from opening to end game.

If I played using my intuition against a chess engine, it can predict which move will make me lose and win.

So this means there is no need for a "chess engine" because all of the possible moves are already recorded.

If such a database exists it would have the following advantages:

* In fast blitz games, chess engine will definitely lose against chess possibility move database.
* We can exactly know which opening will have more opportunity to win against the others.

Or if such a database didn't already exist we could have a mathematical calculation of all possible moves from opening till end game.

Would it be possible for such a database to exist?

# Answer
> 36 votes
I believe your question essentially boils down to the topic of whether it is possible to completely "solve" chess. Wikipedia has an excellent article on the topic which should give you a good overview.

To summarise, the number of possible game variations in chess is estimated to be 10^120. This is a staggeringly huge number, for comparison, consider that the number of atoms in the observable universe is estimated to be around 10^80. In other words, if you were using the entire observable universe as your hard drive, you'd still need to store 10^40 combinations of chess games on *each atom*, in order to simply store it all. Needless to say, this is so far beyond our current and forseeable technologies that most people consider it to be completely impossible.

Chess endgames are considerably less complex, and we've got to a point where it's possible to calculate all possible combinations for five-piece and six-piece endgames. These are typically huge undertakings done by reasearchers with access to supercomputers, and the resulting endgame databases are huge (on the order of hundreds of terabytes). Each time a new piece is added, the size and complexity of the calculations goes up exponentially, which means that in the forseeable future, we can expect these results to expand by only a few pieces.

# Answer
> 13 votes
No, it would not be possible for such a database to exist. Calculating it would require an infeasibly large computer and the calculation would take so long that your computer wouldn't exist for long enough to complete the task.

Claude Shannon estimated that there are around 1043 possible positions in chess and your database would need to store the outcome of all of these (this would be, essentially, a 32-man tablebase). However, it is estimated that the Earth contains only about 1050 atoms so, even if you could build a memory cell out of just 10,000,000 atoms, you would still need a computer the size of the Earth just to store all the positions.

But such a huge computer brings big problems. The earth's diameter is about 12,800 kilometres and light takes about 43ms to cross that distance. That means that, if a clock cycle lasts longer than 43ms, then not only do you have horrible clock skew but different parts of your computer aren't even on the same clock cycle. Avoiding this limits your clock speed to about 23.5Hz (not GHz or MHz; just Hz). Even if you could completely evaluate a position in a single clock cycle, that means your computer would take about 4.3x1041 seconds to complete its task. That's about 1.4x1034 years. That's 14 million billion billion billion years.

Astrophysicists believe that the universe will look radically different in 1.4x1034 years than it does now. By then, stars will have long ago ceased to exist and even elements that are in no meaningful sense radioactive will have undergone large amounts of radioactive decay. Even the protons that form atomic nuclei will have undergone significant radioactive decay. So your earth-sized computer simply won't exist any more.

# Answer
> 6 votes
I think Daniel's answer is excellent (+1) but want to add a few thoughts anyway.

Would a 32-piece tablebase really replace chess engines? The answer is definitely no!

To play good chess, more information is needed than whether a move is winning, drawing or losing. Of course such a database would be unbeatable, but it would hardly beat anybody either.

To play chess strongly it is not enough to chose a non-losing move at every turn. Of the many drawing moves in each position, there are only a few that put real pressure on the opponent.

Existing chess engines are made significantly stronger by accessing tablebases. But as the databases grow, the access time would become a prohibiting factor long before using every atom in the universe for memory ;-).

So I think your conclusion is just wrong: Such a database would never lose and hardly ever win. It wouldn't tell us anything about openings except that almost all of them are draws. We could probably devise new algorithms to mine this database and come up with interesting conclusions about all kinds of positions, but I think this wouldn't change the world of chess in any significant way.

# Answer
> 3 votes
I think someday chess will be solved. Why? Because, well, not that long ago, playing chess against a computer was weird and unthinkable! How could you train a computer to play chess? Well, they did it! (In addition, the idea of a computer was strange...) My point is, it might seem weird because we've never seen of or heard of it. Its not something we can easily imagine. But technology is expanding at an exponential rate. I wouldn't be surprised if in the near future (10+ years) that it is solved, in one form or another.

# Answer
> 2 votes
Back in college in the early 1980s, I read in a game playing text that if a computer could plan, evaluate and execute a move, any single move, from the start of the game to all possible conclusions every 1/3 of a nanosecond, that is approximately 3 *billion* moves/second, to do this for every conceivable outcome would take 10 to the 120th centuries to complete. And who has that long to wait?

Another staggering statistic? You've obvious heard of a googol? Not THE Google, but the number? It is 10 to the 100th power. A 10 followed by 100 zeros. Now imagine the googolplex. That's 10 to the googol'th power.

I've read that there isn't enough of *anything* in the known universe, not even atoms, to require using the googleplex. In fact, even the googol is too big to describe anything. You should check out some of the astonishing trivia about these numbers.

# Answer
> 1 votes
If you use "pruning" you can delete the bad options (the ones that will lead you to a loss for sure) and keep on looping while pruning. This way you might have enough memory to store the "good" options.

# Answer
> 0 votes
Although it might not be possible to realise chess in a database in this universe, the abstract structure of the game can be said to exist as a finite mathematical object. One can reason about it and conclude that it has a definite result, although we might not know what that is. And then if you view it as a matrix you can ask questions like what is the maximum eigenvalue of chess approximately. Indeed Plato thought that numbers have real existence, so I guess he would say that the chess game exists in the same sublime and unhelpful way.

But more practically, I could imagine an advanced quantum computer might genuinely be able to represent this, and indeed solve chess. The jury is still out as to the capabilities of this technology, but in principle I can’t see that it’s impossible

---
Tags: opening, theory, endgame, middlegame, database
---


# Question
Title: Technique to win this same colored bishop endgame
The following endgame is a same-colored bishop endgame which I had on a game in Lichess. I tried for approximately 30 moves to try and win this game, but in the end, I got nothing more than a draw. I just felt that I was better due to white having 4 isolated pawns and 3 on light squares. Stockfish 11 evaluates the position as -4.3 at depth 40. The position in black to move. Please explain to me the technique to win this endgame.

# Answer
> 9 votes
The key here is zugzwang - White has an ideal defensive position at the moment, his king stops yours penetrating, his bishop covers the weak pawns on g4 and c4, and the pawn on a5 you can't easily get at is it is on a black square. BUT when white has to move he will either have to move his king (letting your king in), or move his bishop (leaving a pawn undefended) or move his a pawn (giving you an extra passed pawn)

So how can you take advantage of this? Well... if your bishop was on e6 and it was white's move he would be in zugzwang, and would either immediately drop a pawn (through a bishop or pawn move) or very soon afterwards (through a king move). Now note you can't just move your bishop straight to e6 as this would leave a position where you, not white, has the move. What you have to do is lose a move with the bishop - sometimes called triangulating with the bishop in reference to the similar idea with the King:

```
[Event ""]
[Site ""]
[Date "????.??.??"]
[Round ""]
[White ""]
[Black ""]
[Result "*"]
[FEN "8/1p6/5p2/P1p1k1p1/b1P1P1P1/4K3/4B3/8 b - - 0 1"]

1...Be8
    ( 1...Bd7?! 2.Bd1 Be6 3.Be2 {And white is OK for the moment
    } )
    ( 1...Kd6?? {Trying to get to the a pawn} 2.e5+ Kxe5 3.Bf3 Kd6 4.Bxb7 )
2.Bf1 Bd7
    {so losing a move}
3.Be2 Be6
    {Now white has the move and has to give you something}
4.Bf3
    ( 4.Kf3 Kd4 )
    ( 4.Kd3 Kf4 )
    ( 4.Kf2 {Stockfish's Choice} 4...Kd4
        ( 4...Kxe4?? {Be Careful!} 5.Bf3+ )
    5.Bf3 Kxc4 6.e5 fxe5 7.Bxb7 Kb5 8.a6 Kb6 )
4...Bxc4
    {and wins}
*

```

There's a free course at chessable (https://www.chessable.com/) called "Basic Endgames" which covers this, amongst many other things

---
Tags: endgame, bishop-endgame, isolated-pawn, fortress
---


title: Good books to learn the Ruy Lopez with

text:
# Question
Title: Good books to learn the Ruy Lopez with
I have a very poor repertoire; with White I only play d4, and though I'm quite familiarized with the possibilities on this opening move, I'm lost regarding 1. e4.

Trying to gain flexibility, I want to start to play 1. e4 and, why not, learn the Ruy Lopez. Does anybody know a good resource or book to use to learn this opening? My rating is relatively high and my opponents are most likely going to know the book, so I can not enter this unprepared!

# Answer
> 4 votes
It's quite surprising how few opening books for playing the Ruy Lopez as white there are, given that it's one of those lines that have a claim of being "the main line of chess".

Greet's *Play the Ruy Lopez* is from 2006. Shaw's *Starting Out: the Ruy Lopez* from 2003. Khalifman had the Ruy Lopez in his *Opening for White according to Anand* series but it was very detailed, very high level and is also getting old.

Doknjas' *Opening Repertoire: The Ruy Lopez* was published last year, so it is easily the most recent white report in the Ruy. The writer is an FM, I have no idea how good of a writer he is. Here is a review at the BCF site.

But my vote goes to McDonald's *Ruy Lopez: Move By Move* for a first book on the Ruy.

Because it is very focused on the ideas of the opening, and it has a plan for how you should start playing the opening: first you play safe lines based on an early d2-d3, which are fine and played by the world top, and then later when you want to you can expand into more and more complex lines by playing d3 later in the game, or never. So it contains two repertoires in the closed Ruy, one with d2-d3 and one aiming for d2-d4.

Only if you are substantially stronger than 2000 OTB, already understand the structures and want ambitious concrete up to date theory, then I would get Doknjas as it is very recent.

And if Parimarjan Negi ever finishes the Ruy Lopez repertoire for Quality Chess he is writing, then that probably becomes THE book for strong players immediately.

# Answer
> 2 votes
If it doesn't have to be a book, I can highly recommend Fabiano Caruana's 3-volume video course on the Ruy Lopez, published by chessbase. Caruana lays out a full repertoire for white in the Ruy, discusses common themes and ideas, critical lines, reasons for his recommendations, and example games, often played by himself. Excellent stuff!

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


title: E6 Pin in Classical Dutch

text:
# Question
Title: E6 Pin in Classical Dutch
In a classical dutch setup, if white doesn't fianchetto and instead moves bishop c4 then it pins the e6 pawn. I don't really want to go into the stonewall even though that's the recommendation of the engine. Is there any variation or move that can get me out that is NOT the stonewall?

```
[FEN "rnbq1rk1/ppppb1pp/4pn2/5pB1/2BP4/4PN2/PPP2PPP/RN1Q1RK1 b - - 0 1"]

```

# Answer
> 2 votes
The pin of the `e6` pawn doesn't seem important at all in this position. In fact, it is hard to see what White is trying to accomplish with `Bc4`.

By "going into Stonewall" I guess you mean `.. d5`, and that is certainly tempting, seeing as White will have to lose a tempo just to put his Bishop on another not-great square. For an alternative, consider `.. Nc6`, getting ready for `b6` and `Bb7` deploying your light-square Bishop beautifully with action on the central squares `d5` and `e4`. Also, after `.. Nc6` the `d5` idea will never work for White due to `.. Nxd5!` and White's `g5` Bishop is hanging.

---
Tags: opening, dutch-defense
---


# Question
Title: In Caro-Kann, which one is less risky, the main line or the Steinitz?
After 1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4, the most popular move (main line) is 4...Bf5. But former world champion Anatoly Karpov seems to like 4...Nd7. Since Karpov's style is "solidly positional, taking no risks but reacting mercilessly to any tiny errors made by his opponents," I am wondering if 4...Nd7 is generally considered more solid and less risky than 4...Bf5, at least by Karpov.

I am hoping that Anatoly Karpov can answer or comment on this question, but it does not seem realistic.

# Answer
Regarding your question, as far as I remember, both lines hold.

* `Bf5` gave White a lot of options to fight for an advantage. It got revamped with the help of the computers, Black seeking to generate more active counter-play by castling short instead of long, but I had no courage to try those positions out as they were too wild for my taste.
* `Nd7` was regarded as more solid, giving White less attacking options, but also requires more enterprising play from Black.

Sadly, user `q.undertow` is right. There is no safe line in the Caro-Kann.

Allow me to explain why:

Since it's creation, it was considered inferior to French defense, masters arguing that `1...c6` is too slow, Black not fighting energetically enough for the center. This fact gives White enough time to put pressure on Black. This will always be the case with Caro, Black argues that he will be able to withstand the pressure and cash in White's over-extension in the endgame.

In some lines, White plays outrageous moves, almost "all-in"-ing, forcing Black to invest reasonable risk, in order not to lose. These positions are ugly for the eye of the beholder, but that does not matter. What matters is that objectively, the positions are sound and not inferior for Black.

Before the endgame, comes middlegame. Relinquishing initiative to White, Black will have to defend some serious threats and nobody in the old days knew just how far can White go with his aggression. They tried to play positionally, relying on general principles, but this approach gave only a small plus for White, so he turned to "all-in"-ing, backed by computer analysis. These new moves broke every principle they could, but still remained viable, forcing Black to reply in equal manner in order not to get crushed, generating mind-boggling positions.

Sadly, **it is White who steers the game, so if he wants to, he can drag you into sharp positions.** Positional lines hold for Black (last time I checked) so you should have no problems there as their plans are not difficult to grasp.

If you do get dragged in the complications, **book yourself up**, you won't be able to save yourself with calculation and general principles. From my experience, it was harder to play as Black, more stress, easier to make a mistake, less options to generate counter-play...
> 4 votes

# Answer
IMO it is an overstatement to say that Karpov took no risks. Just to give one example which is curiously on topic, in one of his Caro games he played an early `.. Ke8-e7 !?` in order to connect his Rh8 to his Queen, and got an advantage that way. I would call his style "positional dynamic" or something like that.

Perhaps the larger point is that in chess you simply can't win without taking at least some minimal risk. And I'm hoping that winning (sometimes) is your goal, rather than always drawing.

And there's a risk to systems like `.. Bf5` too, though of a different kind: that of being stuck in a minimally worse position with no counterplay. Playing that sort of position against a master is no fun at all.
> 3 votes

# Answer
From Fundamental Chess Openings (FCO) by Paul van der Sterren:

"Theory of this opening system (which sadly lacks any widely accepted name) has been enriched with a huge number of sharp and original variations"

Here he is referring to the Karpov variation (which now has a widely accepted name!).

So it's definitely not slow and solid necessarily- white can drag you into an attack still.

If you want a slow and solid variation, may I recommend the following variation: 1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nf6 5. Nxf6 exf6

FCO says of this: "It is solid and fairly simple strategically, but it must be admitted that Black is making a positional sacrifice of some sort. In exchange for obtaining open files, free development for all his pieces and a safe place for his king (supposing that Black castles kingside) Black accepts a doubling of pawns which may eventually boil down to a virtual pawn sacrifice. For if White manages to obtain a passed pawn on the queenside, Black will have nothing to show for it on the kingside. This line is clearly a matter of taste"

I play this from the black side regularly and agree with the assessment above.
> 2 votes

---
Tags: positional-play, caro-kann, karpov
---