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I was analyzing the following position for one of the correspondence games that I am playing. In the position, white is up 2 pawns and with my limited understanding, I can't see any real compensation for black. I checked with Stockfish 10 at depth 29 and it evaluated the position as +0.63. I also checked with Komodo 13.2 which gives the position as +0.50 at depth 25. My question is basically on what is the compensation that black has for the 2 extra pawns or is there, in reality, no compensation and I didn't let the computer go into a higher depth.

Here is the position(Black to move):

[fen "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 w - - 0 1"]
  • 9
    Note : if your correspondance game is ongoing, the tournament rules most probably won't allow you to discuss the game publicly. This can be assimilated to asking for outside help or to cheating. If the game is finished, or if the rules specifically allow you to post such a question online, you should probably mention it in the body of the question. – Evargalo Feb 24 at 13:15
  • @Evargalo He asked a previous question about the rules, and it is permitted. I did mention that it may not be ethical, but it is legal. It was the one RIGHT before this. chess.stackexchange.com/questions/28634/… – PhishMaster Feb 25 at 2:57
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First, I don't think that there is any doubt that black has significant compensation, but clearly, black is still trying to hold this, not win it when talking two computers playing each other. I believe that between two humans, I would probably prefer black.

If you have an eval that says +.63 for white, but black is down two pawns, you have to realize that it means that black has roughly 1.37 in positional compensation.

White obviously has the two pawns, but black has the two bishops in a relatively open position, is ahead in development with the Rd8 already controlling the file, and h4 is a target that at the very least can be used to gain a tempo. Lastly, the g4 square is a wonderful spot for the Bc8, and helps control the open file. Also, the Rf1 is poorly placed, and the Bc1 currently does not have a bright future. One of the extra pawns, although I am going to trade it off, is currently doubled.

I analyzed this using a computer, and it is a VERY difficult position to get a handle on because so many of the moves are almost equal in the evaluations. In each case, what I did was let it get to a depth of 33-37 using Stockfish 11, and then I would advance the game by a move and force in the best move, and then let it get to a depth of 33-37 again, and so on. So, by the time I got to the 16th move of the variation, it was still looking 35+ ply ahead.

Here is the variation I found, and I have notes as to why the moves are being played. At the end, it is still only +.41, and despite the two pawns minus, it is hard to believe that white can win due to black's incredible activity, and the Kg8 will enter the game soon.

 [FEN "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 b Q - 0 1"]

 1... f6 2. e4 Bg4 3. e6 (3. exf6 Bxf6 4. g3 Bxc3+ 5. bxc3 Rd3 6. Kf2 Re8 7. e5 Rc8 {and black is almost winning...f5 is already the only move so white can play Bf4 next defending g3.}) Bxe6 4. Kf2 Rd3 (4... Bg4 5. Be3 Rd3 6. Rfe1) 5. Rd1 (5. Be3 Bg4 6. Rac1 Re8) 5... Rxd1 6. Nxd1 Rc8 7. Nc3 f5 8. e5 Bf8 {Ba3 threat.} 9. Bd2 a5 {Idea a4-a3.} 10. Ke1 {To prophylactically protect the Bd2 after a4; Na4 Rc2} Bc5 11. Rd1 Be7 $1 {Only after a2 is undefended does this combined with a4 work.} 12. g3 a4 $1 13. Nxa4 (13. a3 Bb3) 13... Rc2 14. Rc1 Rxc1+ 15. Bxc1 Bxa2 16. Nc3 Bc4 $14 {Nd1 +.41.}
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    3. e6 throwing away the pawn seems odd. Can you tell why that move was chosen? – Brilliand Feb 25 at 2:42
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    @Brilliand The initial answer would be because the computer said so, but it is impossible to keep the pawn, so that was the best way to give it back. I added a line that shows how easily white can get into deep trouble if he tries to hang on to the pawn with exf6 since there is no time for e5 since h4 hangs, and is more important there. – PhishMaster Feb 25 at 2:52
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The formula for winning a position at this stage of the game when you are 2 pawns up goes like this:

  1. Swap the pieces off, or at least enough to make stage 2 possible
  2. Create a passed pawn
  3. Queen the pawn

The problem here is that white is struggling to complete development and black is the one who has all the control.

  • Black controls the open d file
  • Black can control the d1 square next to white's king by Bg4
  • Black controls the white squares
  • Black's g7 bishop potentially controls the a1-g8 diagonal and if the f7 and e5 pawns are exchanged then this could be very painful for white
  • Black's development is almost complete while it is hard to see how white can get any of his pieces to good squares any time soon without losing material. The white queenside rook and bishop don't look like they are going to be playing an active role for a while.

In short, white is probably going to have to give up material just to get to stage 1 alive. The question remains can white complete stage 1 and still have prospects of stage 2, creating a passed pawn? The low evaluation of about 0.5-0.6 suggests that there are some chances but everything is still to play for.

2

First of all, white's pieces don't have much mobility. The B has one legal move, the queen's rook also only has one move, the king's rook only has four moves and none of them are particularly good. The king is kind of in the way. White is going to have to spend some time coordinating his pieces.

Second, black has the two Bishops.

Third, white's pawns are doubled and there is no clear way to advance them in the short term.

There isn't not enough compensation for two pawns but certainly black's more active position is worth at least a pawn, maybe a little more and that's what the engines are saying.

-1

When you get those results from an engine that shows the game is essentially even while you see a two pawn difference then that means you do not fully understand the value of positions.

Black has the two bishops. With Bg4 he will control the file his rook is on and finish his mobilization.

White will have problems getting his pieces onto useful squares. The white bishop is bad as whites pawns block the bishop

Black will double rooks on the queen file threatening a pawn and the bishop if white moves it to d2.

p-f6 will be double edged freeing the black bishop but giving white a potential passed pawn in the late endgame. White could advance the behind 3 pawn to reblock the bishop. black should wait on that move until rooks and other bishop are deployed.

Overall it is a tough position with a lot of play and white has a minimal edge that might matter between computers but not so much between people who actually do the moves.

If you are black I suggest you offer a draw. Especially since you have been getting outside help by posting the question about an ongoing ICCF game online. If you are white I suggest you offer a draw and hope black takes it.

  • What is the problem if I have been getting outside help by posting a question? In your answer, you didn't state that it was against their rules. Also in this question, I wasn't getting help on what move was the best, but instead on the reasoning behind the evaluation of the engine. – SubhanKhan Feb 24 at 21:33
  • I dont care about their rules. You dont care about their rules. This is whether I have ethics. And whether your ethics are different. I dont need to tell you their rules. If you care about their rules you would read them and heed them. Asking for help on the engine reasoning helps you decide how to best use the engine and is against their rules. NO outside help from people of any kind is sort of implied if not explicitly stated that way. – edwina oliver Feb 24 at 23:13
  • Could you please give some evidence of your claims on their rules. I read their rules and I asked the question to double-check since I didn't want to go against their rules. I am quoting your comment above in which you said: "You don't care about their rules". Where is your evidence for the claims that you are making? If I didn't care about their rules I wouldn't have asked that question. The reason I posted on that position was that Phishmaster gave the evidence that it was allowed in their terms. For once don't be ignorant, please. – SubhanKhan Feb 25 at 4:17
  • You asked a question about a postal ICCF game you were playing. Now if your postal is not ICCF but some web site event then their rules may be different. To me postal chess without further elaboration means ICCF. ICCF says no help from people. If you ask anything about a position that would be getting help from people. Even if you dont think so. – edwina oliver Feb 25 at 14:41
  • I read their terms and I couldn't find it anywhere, so if you yourself are so certain that it's against their terms then give evidence and this will be the end of the argument. You might be confusing it with the USCF. – SubhanKhan Feb 25 at 23:57

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