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Tough for Engines - Trapped Piece Detection & Zugzwang..
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Mark Pearce



Joined: 12 Jan 2012
Posts: 61
Location: London, England
PostPost subject: Re: Tough for Engines - Trapped Piece Detection & Zugzwa    Posted: Sat Jun 02, 2012 1:44 pm Reply to topic Reply with quote
Steve Maughan wrote:

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

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

Moving on 2 ply from your initial position (i.e. Be6+, Ke8), Houdini 2.0 finds the win of the Black queen in 14 minutes. This is using 2 cores and 1 GB cache on a i7 2600K. I will now try it on your initial position.
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Display posts from previous:   
Subject Author Date/Time
Tough for Engines - Trapped Piece Detection & Zugzwang.. Steve Maughan Fri May 25, 2012 3:52 pm
      Re: Tough for Engines - Trapped Piece Detection & Zugzwa Gabriel LEPERLIER Fri May 25, 2012 7:48 pm
      Re: Tough for Engines - Trapped Piece Detection & Zugzwa Mark Pearce Sat Jun 02, 2012 1:44 pm
      Re: Tough for Engines - Trapped Piece Detection & Zugzwa Vincent Diepeveen Sat Jun 02, 2012 3:51 pm
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