Author: Dann Corbit
Date: 12:39:18 06/07/99
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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.
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