17

I recently played an endgame as Black in which I though up a silly, but effective, to advance my doubled pawns. Here’s the relevant part of the game.

[FEN "8/6p1/2p2kp1/1p1p4/p2P2K1/P1P5/1P6/8 w - - 0 1"]

1. Kf4 g5+ 2. Kg4 g6 3. Kg3 Kf5 4. Kf3 g4+ 5. Kg3 g5 6. Kg2 Kf4 7. Kf2 g3+ 8. Kg2 g4

Then White ran out of time and I won.

We were both down to the seconds on the clock, and I thought that this was a good idea. That was because I thought, “Why must I think, when I can just herd the White king down the board is a systematic manner that saves me from wasting too much time on future thought?”

However, was my “caterpillar” plan really a good strategy in this endgame situation?

12

tl;dr: "Yes."

Discussion: Technically, this position is governed by the basic concept of the "Outside Passed Pawn" and the winning method is to use that pawn to restrict the opposing king's ability to defend the other pawns on the board.

The purest expression of that concept is in David's answer, which is to just use the one pawn and leave the other as a Damoclean Sword dangling over the head of your opponent's king.

But, given the special case of this situation (you actually have two outside passed pawns, not just one) you could also decide play it strictly as a single g-pawn endgame, but with tempo move in hand. To do this, you would use the caterpillar's "head" (the lead g-pawn) along with your king to drive the opposing king backwards to the back rank. (While doing this, when your king moves beside your pawn, keep it to the center -- f file -- side of your g-pawn.) When that is accomplished (let's say your K reaches f3, the pawn g3 and your opponent's K goes to f1 to prevent your king from advancing in front of the pawn) you simply push the g-pawn forward to g2 and when he moves to g1 to block the advance of the pawn, then you move the rearmost g-pawn from g7 to g6, leaving your opponent the choice of getting out of the way of your lead g-pawn and letting it queen, or moving one of his other pawns and letting you create a queen from one of your other pawns.

I would probably have played it that way, simply because it seems the least complicated to me, but there are multiple winning ideas in this position, and none of them are objectively better than any other.

11

Overall, that is totally fine, and it worked great. That said, without a detailed calculation of any promotion and stalemate possibilities on the k-side, the easiest win will be running to b2 and just queening the a-pawn since you may well have to do that anyway. That is best done with the p on g6 still far away, and white cannot ignore it, so he has to go take that first, and that is VERY slow.

My initial instinct was to run to b2 much earlier. It is simpler.

P.S. Also, as Taemyr first mentioned, and then OverlordAlex, there really is no stalemate threat since even if you get to g2+; Kg1 Kg3; white still has b3 ab; a4 b2; a5 b1=Q and mate. I should not have even worried about that.

  [FEN "8/6p1/2p2kp1/1p1p4/p2P2K1/P1P5/1P6/8 w - - 0 1"]

1. Kf4 g5+ 2. Kg4 g6 3. Kg3 Kf5 4. Kf3 g4+ 5. Kg3 Ke4 6. Kxg4 Kd3 7. Kg5 Kc2 8. Kxg6 Kxb2 9. Kf6 Kxa3 10. Ke6 Kb3 11. Kd6 a3 12. Kc6 a2 13. Kd5 a1=Q
  • 1
    It does not matter for an engine, but playing Kc4 after you've gobbled up the pawns (e.g. instead of 11. .. a3) simplifies further calculation, as you can essentially premove up to checkmate. – phihag Oct 23 at 8:53
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    @phihag You are correct, or even on the next move. I actually did not do that with an engine, and the end position is so easy that I did not look for a better move, but that is even that much easier. Good call. – PhishMaster Oct 23 at 9:56
9

White is in zugzwang so the basic idea of forcing white back using the pawns for extra tempos is perfectly correct.

You still need to figure out how to queen without stalemating but you have the right idea.

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    Stalemating is not a problem as white has queenside pawns that he will be forced to move, giving black an alternative path to victory. Absent those paws is another question.. – OverlordAlex Oct 22 at 13:10
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    "zugzwang" is an English word? I didn't expect that. "Blitzkrieg" ok, because it has a unique historical meaning, but "zugzwang"? – HeadhunterKev Oct 22 at 13:52
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    @HeadhunterKev English or not, it is a chess term. (Sadly, I only know that from watching Criminal Minds, but still...) – T.J.L. Oct 22 at 14:49
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    "zugzwang" wikipedia entry: en.wikipedia.org/wiki/Zugzwang (TIL) – aloisdg says Reinstate Monica Oct 22 at 15:41
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It was OK, but unnecessary. You could have left your "back" pawn on the starting square to make your opponent lose more time while going to capture it. Then you are free to go into the queenside to take all of his pawns.

The endgame is easily won anyway so there is no one road do victory, though. For instance, you could end up with your pawns leaving the White king with no moves, forcing him to give his panws away (but beware of stalemate!)

1

It was a very sensible strategy. You never have to worry about stalemate because at the key moment, like round about now, your king can head over to the queenside to take the pawns on b2 and a3 and then queen your a pawn while your opponent is busy taking your g pawns.

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    He doesn't have to worry about stalemate because if white is unable to move his king white is forced to move a pawn. – Taemyr Oct 22 at 10:53
1

From the end position without the queenside pawns White can move to g1, claim the opposition, and have a draw. If you had just advanced the front g pawn until it got to g3 you would have g6 available to take the opposition and queen the front g pawn.

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