Premature search stop in Crafty 25.3

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MOBMAT
Posts: 90
Joined: Sat Feb 04, 2017 10:57 pm
Location: USA

Premature search stop in Crafty 25.3

Post by MOBMAT » Sun Nov 24, 2019 6:04 pm

I tested Crafty 25.3 and 25.2 for that matter on this position:


It is a mate in 9, pretty easy for most engines.
Crafty starts the search and then abruptly stop the search prior to finding the mate in nine.
Here is the analysis from Arena. The earlier ply info was not output by Crafty (time savings, I presume).

Code: Select all

E:\Chess\Arena\TestSuites\M09-Test.epd  Position 5 / 28 Bg3-b8  M9
FEN: 6R1/k7/P7/PP6/8/1K1p2B1/6pP/6br w - - 0 1

Crafty 25.3:
 23	00:01	 11,694k	11,353k	+M10	1.Kc4 d2 2.Bb8+ Ka8 3.b6 Bxb6 4.axb6 Rc1+ 5.Kb5 Rb1+ 6.Kc6 Rxb6+ 7.Kxb6 g1Q+ 8.Rxg1 d1Q 9.Rxd1 Kxb8 10.Rd8+
 23	00:00	 1,367k	12,425k	+M10	1.Kc4 d2 2.Bb8+ Ka8 3.b6 Bxb6 4.axb6 Rc1+ 5.Kb5 Rb1+ 6.Kc6 Rxb6+ 7.Kxb6 g1Q+ 8.Rxg1 d1Q 9.Rxd1 Kxb8 10.Rd8+
 23	00:00	 2k	2k	+M10	1.Kc4 d2 2.Bb8+ Ka8 3.b6 Bxb6 4.axb6 Rc1+ 5.Kb5 Rb1+ 6.Kc6 Rxb6+ 7.Kxb6 g1Q+ 8.Rxg1 d1Q 9.Rxd1 Kxb8 10.Rd8+

Is there a configuration parameter that will prevent Crafty from ending the search prematurely?
Here is my crafty.rc file:

Code: Select all

mt 4 
smpnice=1 
egtb 
tbpath=g:\Syzygy; 
hash=16384M 
hashp=128M 
ponder off 
learn 0 
book off 
log=off 
swindle off 
exit
I've noticed this behavior with other engines and I'm guilty of implementing the same type of logic in one of my engine implementations, but for doing puzzle analysis, engines need to be able to search forever (at least till they run out of ply).
Vince S
Author of MOBMAT

"Reductions, extensions, and pruning, oh my!"

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