Author: Michael Henderson
Date: 13:10:30 09/25/04
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On September 25, 2004 at 10:30:52, Rick Bischoff wrote: >Hi, > >I am confused about the mate threat extension. I have the following code: > >search ( depth, alpha, beta ) > >->check extension >->else pawn extension > >->if depth <= 0 do the queiscent > >->if checkReps return draw >->if insufficnetMaterial return draw > >->Probe the hash table and return if good > >->if not in check and depth>3 and last move was not null and material is ok: >->-> do null move >->-> x = -search(depth - 3, -beta, -beta +1 ) >->-> undo null move >->-> if ( x >= beta ) return beta >->-> if ( x < (-MATE+MAXPLY) ) cout << "found mate" > >->normal alpha/beta stuff > >end search > >"found mate" never gets printed out in WAC141 unless I change the null move to a >full width search... Why? Well, I shouldn't say never, but I let it run to ply >9. some questions: fail soft or fail hard alpha beta? How do you detect mates in the search? -- king capturing or static IsMate() function? If your depth is >= 4 only then you do null move, that might be too high up in the tree for mate threats--I think your mate threats are going to your main alpha beta stuff. Try doing null move regardless of depth and see what result you get. Michael
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