Author: blass uri
Date: 13:35:24 06/07/99
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On June 07, 1999 at 15:39:18, Dann Corbit wrote: >On June 07, 1999 at 15:16:23, blass uri wrote: >[snip] >>>Dann: >>>In my database (for which basically all positions are from actual games) I have >>>218 promotions where promotion to knight is clearly the best move, 85 where >>>promotion to bishop is the best move, and 147 promotions to rook. Consider the >>>following: >>>6n1/5P1k/7p/np4b1/3B4/1pP4P/5PP1/1b4K1 w - -; ce 32766; pv f8=N#; bm f8=N#; id >>>"BWTC.0907"; >>>4K3/5P1k/8/8/7N/8/8/8 w - -; ce 32758; pv f8=B Kg8 Nf3 Kh7 Kf7 Kh8 Bg7+ Kh7 >>>Ng5#; bm f8=B; id "IMCP.015"; >>>4K3/3P4/3kN3/8/4PP2/8/8/8 w - -; ce 32762; pv d8=R+ Kc6 Rb8 Kd6 Rb6#; bm d8=R+; >>>id "IMCP.070"; >>How many games do you have in your database? >Depends on what you mean. The figures come from C.A.P. data, for which there >are one half million board positions. They are broadly slanted towards the >openings, so promotions are not as frequent as you might think. The figure for >promotion to queen in the same set of rows is: >6570 >and so the positions where not having underpromotion will hurt you are about >(218+85+147)/(6570) >= 450/6570 = .0685 >so about 7% of the time an underpromotion is needed!!! >That sounds like a *very* signficant hole to me. In part of these 7% of the cases(including your 3 examples) underpromotion is needed only to win faster but is not important practically for the result of the game. Uri
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