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Subject: Re: Revisiting WCSAC #398

Author: Frank Schneider

Date: 23:45:34 08/22/03

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On August 22, 2003 at 10:54:17, Steven Edwards wrote:

>The following position is #398 from _Winning Chess Sacrifices and Combinations_:
>
>[D]2qrr1n1/3b1kp1/2pBpn1p/1p2PP2/p2P4/1BP5/P3Q1PP/4RRK1 w - - 0 1
>
>It has been referenced in a number of CC papers over the past three decades
>including the description of the NWU program Chess 4.x by Slate and Atkin.  It
>was also a test position for the MacLisp Paradise program by David Wilkins at
>SRI.
>
>The position is a mate in ten.  My old program Spector, moribund for seven
>years, picks the key move 1. Qh5+ at iteration eight as "obviously winning" and
>sees the full mate PV on iteration nine.
>
>PV: Qh5+ Nxh5 fxe6+ Kg6 Bc2+ Kg5 Rf5+ Kg6 Rf6+ Kg5 Rg6+ Kh4 Re4+ Nf4 Rxf4+ Kh5
>Rg3 Re7 Bg6#
>
>Spector requires over fifty million nodes for the complete search and I'll guess
>that the numbers aren't all that much different for most programs using common
>search techniques.
>
>BUT, the above mentioned Paradise chess program pulls out the mate PV with a
>search tree containing only 109 nodes.  It solves many other tactical puzzles
>with similarly small search trees.
>
>Are there any programs out there today that emphasize knowledge per node rather
>than nodes per second?

Gromit 3.10.16 (predecessor of Anaconda) on an iPAQ 3660, 8MB Hash needed
35sec to find Qh5 and announces a Mate in 10 after 68sec (iteration 7), which
is about 320000 nodes.

Frank






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