Author: Tord Romstad
Date: 08:57:40 10/12/03
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On October 12, 2003 at 09:47:39, Uri Blass wrote: >If you searches checks every where in the search then by definition >you find the draw at ply 1 if your program has stalemate detection in its >evaluation. > >[D]r7/8/8/8/8/PPPP4/2QP4/k6K b - - 0 1 > >If it does not detect the draw at depth 1 even with checks everywhere then we >have different definition of everywhere so you should expalin your definition of >everywhere. I haven't tried it, but I am 100% sure I wouldn't get a draw score at ply 1 in this position. My guess is that Gothmog would need many hours to return a draw score. My definition of "checks everywhere" is the checks are not limited to the first ply of qsearch, but can in theory be generated and searched at all deeper plies of the qsearch. In this respect, I do use checks everywhere. I do not, however, search *all* checks everywhere. In particular, I try to prevent the qsearch from exploding by generating checks at deeper plies only if the number of replies to the previous checks is very limited. Beyond the first few plies, I *only* search checks if *all* the previous moves of the opponent in the qsearch have been single-reply-to-checks. There are also several further restrictions (for instance I don't search checks in positions where the side to move has a huge material advantage). Another reason I cannot solve your position is that I only include checks in the qsearch in middle-game positions, and your position is classified as an endgame position. >extending escape to checks everywhere is not enough to search checks everywhere >and you need also to generate all possible checks everywhere. > >If after some checks by the black rook you stop generating rook checks then you >do not generate checks everywhere. > >I do not believe that Diep or Hiarcs or Chessmaster extend checks everywhere by >my definition. I also don't think so. Extending checks everywhere by your definition is probably not even possible; there are almost certainly positions where even a 1-ply search would not terminate within a reasonable amount of time. Tord
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