Author: Tony Werten
Date: 22:24:24 05/04/04
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On May 04, 2004 at 11:43:17, Tord Romstad wrote: >On May 04, 2004 at 10:57:34, Tony Werten wrote: > >>On May 04, 2004 at 10:55:20, martin fierz wrote: >> >>>On May 04, 2004 at 10:53:44, martin fierz wrote: >>> >>>>On May 04, 2004 at 10:44:43, Tord Romstad wrote: >>>> >>>>>When there is little thinking time left, my engine annoyingly often fails to win >>>>>KQKR endgames. Are there any simple but effective eval tricks which can help to >>>>>play such endgames well without searching very deeply? >>>>> >>>>>Tord >>>> >>>>none really that i know of. of course there are two, but those are obvious, the >>>>first is easy, the second is hard: get the defending king to the edge of the >>>>board, and if possible, separate king and rook of the defender. but it's tough >>>>to win this on knowldege, i would say - humans at least can hardly win against a >>>>computer defence, and they are nice examples of chess-playing entities not >>>>searching very deeply :-) >>>> >>>>cheers >>>> martin >>> >>>umm, forgot one: of course your king has to be close to the defender's king too. >>>and i really can't think of anything else, but then i never looked at the theory >>>of this endgame. i had to play it once, but for a human player it's pretty >>>irrelevant to know about this... > >Thanks for the ideas, Martin! > >Unfortunately I already use mostly the same heuristics as you describe >above, but perhaps it would work better with some tuning of the weights. >Experimenting with null move tricks, like Gerd suggested, is another >possibility. > >>You forgot 1 more: Use tablebases .... > >No, they are too big. The KQKR tablebases alone consume more than 1 MB. >:-( Yes, for handhelds etc that's too much. But having the acces code available makes it easier to find general rules. First, throw out all positions where side to move has a winning capture ( your quiesence search will find those ) then throw out "easy" positions ( side to move can give check with hanging queen/ give checkmate, if you include checks in qsearch you will find those too anyway ) then go hunt for exceptions ie rook wins. Tony > >Tord
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