TalkChess.com

[Steve Maughan]

Mc Mad posted this endgame position on the general forum. It got lost in the thread and I think it's of interest to programmers so I'm re-posting here with some analysis:

[d] 5q2/1p1kp3/pP4p1/4B3/3N3K/1B6/P4P2/8 w - - 0 1

The position is really quite deep. The forced win of the Queen is 19 ply. Most of those moves would be regarded as quiet and most forms of selectivity would prune, or aggressively reduce. Most engines struggle, even when shown the first two moves.

From a engine / programming perspective I think the key position is after the following moves:

1. Be6+ Ke8 2. Nf5 gxf5 3. Kg5 f4 4. f3 Kd8

[D]3k1q2/1p2p3/pP2B3/4B1K1/5p2/5P2/P7/8 w - - 0 5

White is a knight down compared to the root position. It isn't zugzwang as black can play a5 with no immediate repercussions. The queen has a safe square to move to as it looks as if she can move to e8 (although it's mate in 1).So aggressive pruning is likely. I think this is difficult for engines to see past this position from the root.

I think only the engines with highly developed code for detecting trapped pieces and zugzwang are able to see it.

Any thoughts?

Steve