Thursday, February 07, 2008

Bug squashing

Yesterday and today I found bugs in Cake's evaluation. I was looking at some games that Cake had lost, and made a change in the evaluation which should have improved the situation. However, although the evaluation was different, the output of the engine remained the same - the exact same number of nodes searched with the same value for the position. That made me *very* suspicious, and I looked at the code a bit more closely, and discovered that during my code cleanup of last summer I had broken a really important piece of knowledge. Being suspicious, I continued looking for bugs and found one minor bug and one cosmetic bug. The match result improved drastically after stomping the first bug, from +19-16 @5s/move to +26-11. I don't have much hope that the minor bug will make a big difference but soon I will see!

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