Author: José de Jesús García Ruvalcaba
Date: 11:56:46 10/09/98
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On October 09, 1998 at 13:04:53, John Coffey wrote: >On October 09, 1998 at 09:38:35, Robert Hyatt wrote: > >>On October 09, 1998 at 02:11:19, Jouni Uski wrote: >> >>>I have feeling, that using 3-5 pieces tablebases don't give any measurable >>>rating gain - may be 2-10 points maximum = no real gain. >>> >>>Jouni >> >> >>I would disagree here, as I see KRP vs KR regularly. In fact, in long >>games on ICC, I'd bet I see this about every 10 games or so. Lonnie >>can comment because he has played against Crafty a lot. And it is quite >>often for two computers to end up a pawn up or down, in the ending, and >>if one knows about this, it will win more, or draw when it should lose, >>than without them. >> >>ditto for endings like KRB vs KR... where it knows to trade into that >>when it can be drawn... > >Fritz5 has KRP vs KR and KQ vs KR. Not sure if it has anything else. > >I wanted to create a tablebase with all the possible K + 2 pawns (or less) >vs all the K + pawn positions. I figured that the number of possible positions >is around 489 million, but if I were to store it 2 bits per position >(win/loss/draw/unknown) then I could get it in 128 megs. > >John Coffey To make a tablebase, you need all of its descendants first. The direct sons of KPPKP are: KPKP (black captures one white pawn) KPPK (white captures the black pawn) KQPKP (white promotes to a queen) KRPKP (white promotes to a rook) KBPKP (white promotes to a bishop) KNPKP (white promotes to a knight) KPPKQ (black promotes to a queen) KPPKR (black promotes to a rook) KPPKB (black promotes to a bishop) KPPKN (black promotes to a knight) And each one of these has its own sons, which must be calculated first, until you reach KK, KBK or KNK (which are drawn). So, your storage requirements might be a little higher. With so many pawns, a tablebase with little information (like the one you want to make), could be useful, as you can search only the branches which do not decrease the exact score for the side to move.
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