Monday, September 24, 2012

Perft for Checkers for Depth 28

My quest for deeper perft numbers for 8x8 checkers using has reached depth 28. Below you see the perft(28) breakdown per move, called "divide". As stated before, the numbers were computed on a cluster of machines, optimized with a "hard collision"-free transposition table as well as bulk counting. The move generator does not eliminate duplicate captures.

At this point, the limits of 64-bit unsigned integers have been reached. Although there are obvious ways around these restrictions, this seems a very good time to give this (by now probably insane) project a rest. I have updated this OEIS entry up to depth 26, and may add the higher depths also when I am a bit more comfortable with these most recent results.

divide(28)
12-16 = 2400708339858199191
11-16 = 2431386196712611878
11-15 = 2231787529331259810
10-15 = 2186446356811761737
10-14 = 1872427919495823777
 9-14 = 2285893686261887442
 9-13 = 2969067990365356900
 --------------------------
perft(28) = 16377718018836900735