Author: martin fierz
Date: 13:05:13 12/03/04
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On December 03, 2004 at 12:54:47, john tromp wrote: [snip] >Testing for four-in-a-row is done with two shift+and operations >per direction, and the 49-bit key is computed with 2 additions. hi john, i read your post with interest, because i wrote a bitboard-based connect 4 about 2 years ago (www.fierz.ch/4inarow.htm). my test for a win is not very elegant, and so i checked out your version. cute! i am using the concept of threats to evaluate intermediate positions so my program can play a sensible game without calculating to the end. but your win-test is really nice. perhaps i can work out some better way to detect threats with this... >The solver is currently being used to solve connect-4 on bigger >board sizes. Unfortunately, avoiding collisions while storing only >32-bit locks requires a lot of memory, more than I have access to. >For instance, 7x8 and 9x6 boards both require 63-bit keys, which >means the table size must exceed 2^(63-32)=2G, taking 10Gb memory. i don't understand this part. why don't you just increase your key/lock sizes? ok, you might have one collision in a bazillion read/store operations, but does it matter? cheers martin
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