Author: Jeremiah Penery
Date: 22:01:36 09/27/00
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On September 27, 2000 at 04:45:38, Eduard Nemeth wrote: >[D]8/8/p3R3/1p5p/1P5p/6rp/5K1p/7k w - - 0 1 > >Shredder 4 and Fritz 6a this don't find ! I have a modified Crafty that solves this well enough: 7-> 0.33 -0.04 1. Re1+ Rg1 2. Rf1 Rxf1+ 3. Kxf1 a5 4. bxa5 b4 5. a6 b3 8 0.34 -- 1. Re1+ 8 1.85 ++ 1. Re1+!! 8 1.86 0.61 1. Re1+ Rg1 2. Rf1 Rxf1+ 3. Kxf1 a5 4. bxa5 b4 5. a6 b3 6. a7 b2 7. a8=Q# 8-> 1.88 0.61 1. Re1+ Rg1 2. Rf1 Rxf1+ 3. Kxf1 a5 4. bxa5 b4 5. a6 b3 6. a7 b2 7. a8=Q# 9 1.89 -- 1. Re1+ 9 5.86 ++ 1. Re1+!! 9 5.87 Mat07 1. Re1+ Rg1 2. Rf1 Rxf1+ 3. Kxf1 a5 4. bxa5 b4 5. a6 b3 6. a7 b2 7. a8=Q# 9-> 5.89 Mat07 1. Re1+ Rg1 2. Rf1 Rxf1+ 3. Kxf1 a5 4. bxa5 b4 5. a6 b3 6. a7 b2 7. a8=Q# Part of the modifications I did was to not do a nullmove at all when the total depth is 5 or less, and it also doesn't use nullmove when depth_remaining is 2 or less. The normal "adaptive null-move reduction" has also been changed, to only use r=3 when depth is more than 12 instead of the normal 6. Here's the modified parts of the nullmove code from Crafty's search.c if (iteration_depth > 5 && depth > 2) { # if defined(NULL_MOVE_DEPTH) .... null_depth=(depth > 12*INCPLY) ? 2*INCPLY : 3*INCPLY; .... # endif }
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