Author: Robert Hyatt
Date: 11:23:21 10/04/01
Go up one level in this thread
On October 04, 2001 at 00:26:38, Uri Blass wrote: >On October 03, 2001 at 11:30:56, Robert Hyatt wrote: > >>On October 03, 2001 at 09:58:48, Uri Blass wrote: >> >>>On October 03, 2001 at 09:47:04, Chessfun wrote: >>> >>>>On October 03, 2001 at 08:58:28, Uri Blass wrote: >>>> >>>>>I do not understand some draw decisions >>>>> >>>>>For example the following position from bringer's game in the last round: >>>>> >>>>>[D]8/2R5/8/6K1/1k6/7p/6bP/8 b - - 0 107 > > > > > > > > > > > > >>>>> >>>>>The last capture was at move 96 and I am not sure if white cannot win this >>>>>position >>>>> >>>>>If white can get the following position in the game then it seems to me that >>>>>black is losing(I do not have the 5 piece tablebases of KRP vs KB and someone >>>>>with these tablebases can probably say even that it is a forced mate and exactly >>>>>the number of moves. >>>>> >>>>>Uri >>>> >>>>It's mate in 21, but I can't see how White can force black into this position >>>>within 18 more moves. >>>> >>>>Sarah. >>> >>>I also cannot see and the original position may be a draw with exact game >>>If someone decide to build the 6 piece tablebases for 4 pieces with blocked >>>pawns(white pawn at h2 and black pawn at h3) we may know. >>> >>>Maybe it is a good idea to tell chess programs to build these tablebases during >>>a game when the hardware is fast enough and it is tournament time control. >>> >>>It may be a very good option for correspondence games even today. >>> >>>Even if programs need 30 to build these tablebases it may be possible to do it >>>at some tournament time control games when this kind of position is in the root >>>and the program may use 30 minutes for one move but later play always from the >>>tablebases. >>> >>>Uri >> >> >>Did you mean 30 minutes or 30 hours? 30 hours would be very fast for a 6 >>piece file. With pawns, maybe 30 days. > >I did not suggest to generate the full 6 piece tablebase of KRP vs KBP but only >the tablebases for the case when the white pawn is at h2 and the black pawn is >at h3. > >the number of relevant positions to investigate is bounded by 31*61*60*59 in >this case > >31 possibilities for the black bishop(it cannot be at h3 because there is a pawn >there) >61 possibilities for the white rook after putting the bishop >60 possibilities for the white king after puting bishop and rook >59 possibilities for the black king. > >Positions after a capture are known by the 5 piece tablebase so we do not need >to investigate them. > >Uri That is just one case. There are _many_ others with blocked pawns. IE let's make this a KQP vs KRP ending. With the pawns blocked. It turns into a KQ vs KR for tablebase generation purposes. That takes a while... IE it isn't computed in 1 minute or 10 minutes because there are so many iterations to do, and the size of the temporary files are _still_ big... I don't think computing them on the fly is doable. It takes over 2 hours just to compute all the 4 piece endings by themselves...
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