Author: Robert Hyatt
Date: 14:17:50 12/02/05
Go up one level in this thread
On December 02, 2005 at 15:49:11, Paul Jacobean Sacral wrote: >On December 02, 2005 at 15:19:51, chandler yergin wrote: > >>On December 02, 2005 at 14:56:48, Uri Blass wrote: > >>>Engines can say mate in 14 even when there is mate in 11 but not the opposite. >>> >>>Engines should say mate in 11 for white only when they checked all defences of >>>black and found that there is no defence against mate in 11. > >>Engines evaluate all moves 1/2 move i.e. 1 Ply at a time. >>Nothing more.. nothing less. >>The deeper the search the better the evaluation. >>You assert bugs when there is none. > >Excuse me, but with replies like that people will start to think that you are a >troll. Please don't explain to Uri Blass how engines work: He has written an >engine himself. > >Call it bug, mistake, error or whatever you like: If the shortest possible mate >in a position is #14 and an engine displays #11, there is something wrong. Maybe >a rare effect of nullmove pruning or something like that... but #11 is simply >wrong and not a "better evaluation!" :) > >Yours truly Paul J. Sacral That is completely correct. If an engine claims a shorter mate, and it is proven the mate is longer than that, then the engine has a bug, pure and simple. The inverse is not true, since many engines will find a deeper mate and quite before finding the absolute shortest mate (some like Crafty won't do this except when EGTBs are involved) and this is not necessarily a bug, but an artifact of how the search is extended. I am not sure why this has become "disinformation central" all of a sudden...
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