Author: Gerd Isenberg
Date: 23:49:12 11/04/02
Go up one level in this thread
On November 04, 2002 at 19:03:21, Sune Fischer wrote: >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. > Ok, but with conditional move generation of the underpromotions triggerd by undo queen promotion the risk of missing one move is zero. And in most of the cases no additional underpromotions are generated. Gerd >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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