Author: Sune Fischer
Date: 16:03:21 11/04/02
Go up one level in this thread
On November 04, 2002 at 18:46:50, Gerd Isenberg wrote: >On November 04, 2002 at 18:11:59, Sune Fischer wrote: > >>On November 04, 2002 at 16:55:10, Uri Blass wrote: >>> >>>Depth 11 was finished few minutes ago and the score is very convincing. >>>It seems that depth 11 is good not only to find the fail low but also to find >>>the fail high for Be6 >>> >>>11 67 161361 228198851 c8e6 >>>11 319 201885 285759097 c8e6 f4c1 c3c2 b1b2 e6c4 b2a3 c7c5 a3b2 c2d1n g1d1 b4d3 >>>d1d3 c4d3 d4c5 d6c5 c1c5 d8b8 b2c3 d3e4 >>> >>>depth=11 +3.19 c8e6 f4c1 c3c2 b1b2 e6c4 b2a3 c7c5 a3b2 c2d1n g1d1 b4d3 d1d3 c4d3 >>>d4c5 d6c5 c1c5 d8b8 b2c3 d3e4 >>>Nodes: 285759097 NPS: 141545 >>>Time: 00:33:38.85 >>> >>>Uri >> >>Congrats, I knew Movei could do it though :) >>Your PV is 19 plies, so a bit extended. >>Looks like there is a knight promotion, I wonder how often these underpromotions >>aren't fail lows, cause I'm thinking of removing them completely, better branch >>factor and all you know... >>Of couse I would keep them at the root, so as not to have a bug, what do you >>think? >> >>-S. > >Carefull - at least the knight promotion should be considered. But if the >queen-promotion is rejected by capture of the promoted queen, underpromotions >make not much sense, because they may captured as well. If a queen promotion >forces a stalemate-draw, also rook as well as bishop promotions should be >considered. Well yes there is a risk, but how often does it happen? I think searching underpromotions is basicly a waste of time, if the queen promotion isn't good enough, then most likely the others can be discarded as well. Bishop promotions must be very rare, I don't recall ever having seen a PV with a bishop promotion, 99 of 100 it's a queen. And as long as it's deep enough in the search the noise will be very high anyway. I mean, I do not even search my losing captures in qsearch (I sort with SEE) so in that context I consider the search of underpromotions overkill/waste of time (simply cull them like you cull losing captures!). What happens to the branch factor if you don't? Imagine you have a position with 2-3 pawns promoting, in some cases you might have two pawns that both have three possible squares, that's 6 moves for those two pawns, and 6 moves times 4 promotion types, that's 24 moves! Quite a BF explotion :o) -S. >Gerd
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