Author: Tord Romstad
Date: 04:50:52 02/20/06
Go up one level in this thread
On February 19, 2006 at 22:11:11, Sean Mintz wrote: >As I try to figure this out, perhaps you have an idea as to what it might be: > >[D]8/2p5/3p4/KP5r/1R3p1k/8/4P1P1/8 w - - > >depth correct what I get > >1 14 14 >2 191 191 >3 2,812 2,812 >4 43,238 43,238 >5 674,624 674,624 >6 11,030,083 11,030,078 > >So, at a depth of 6 ply, I come up 5 moves short. I don't have any good advice about this particular position, but this is how I solve this sort of problems in general: First, you need an open source program which you know give correct perft scores (i.e. Crafty). Modify this program to print perft numbers not only print the perft number for the position for the board, but also each subtree below each move at ply 1. For the position above, you should get output similar to the following: Subtree below move e2e3: 745505 Subtree below move g2g3: 271220 Subtree below move e2e4: 597519 Subtree below move g2g4: 892781 Subtree below move b4b1: 1160678 Subtree below move b4b2: 818501 Subtree below move b4b3: 941129 Subtree below move b4a4: 745667 Subtree below move b4c4: 1027199 Subtree below move b4d4: 957108 Subtree below move b4e4: 860971 Subtree below move b4f4: 174919 Subtree below move a5a4: 868162 Subtree below move a5a6: 968724 perft(6) = 11030083 Make your own program print similar statistics for each move. For at least one of the moves, the numbers will differ between the two programs. Execute this move in both programs, and do a perft(5) from the resulting position. By using this procedure recursively, you will quickly be able to zoom in on the exact position where your program generates too few (or too many) legal moves. Good luck! Tord
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