Author: Ernst A. Heinz
Date: 11:31:02 10/27/98
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On October 27, 1998 at 14:18:45, Roberto Waldteufel wrote: > > [...] > >If your code detects that one side has an unstoppable passed pawn when the >opponent has only king and pawns left, how do you establish that the opponent >can't do something nasty like capture one of your pawns on the 2nd rank thereby >creating a more advanced passed pawn on the 6th rank, or even worse trapping >and >mating your king with an onslaught of king and several pawns, aided perhaps by >some squares being blocked by your own pawns? I use an array of bitboards >indexed by side to move and king position (ie 128 bitmaps) which tells me which >squares would be "unstoppable" squares for pawns. However, I only use this to >determine trivial wins when one side has only a bare king, and when prior tests >have determined that I do not have mating material unless I promote a pawn. I >think the same quick "unstoppable passed pawn test" might be useful when the >losing side has some pawns as well, but I never figured out a satisfactory way >to tell whether the unstoppable passed pawn was enough to be sure of victory or >not in this more complicated situation. I would be interested to know how you >handled this. That's exactly why I said I deem the "square of the pawn" rule as being too simplistic. :-) Actually, you only need to account for the Pawn races in your evaluation function but *not* for possible mating scenarios which should be resolved by the search in general. =Ernst=
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