Author: martin fierz
Date: 13:15:21 07/22/04
Go up one level in this thread
On July 22, 2004 at 12:25:04, José Carlos wrote: >On July 22, 2004 at 09:57:37, martin fierz wrote: > >>On July 22, 2004 at 08:24:32, Anthony Cozzie wrote: >> >>>On July 21, 2004 at 10:20:30, Albert Silver wrote: >>> >>>>Hi, >>>> >>>>This is probably old news to many, but I ran across the pages of Michael Buro >>>>(http://www.cs.ualberta.ca/~mburo/), and saw an article on ProbCut, highly >>>>recommending it, and even mentioning its inclusion in a version of Crafty 18.15. >>>> >>>>"ProbCut works in chess on top of null-move search! Download >>>>mpc_crafty_18.15.tgz to play with it. We encourage all chess programmers to >>>>experiment with ProbCut!" >>>> >>>>One can download the article "ProbCut: An Effective Selective Extension of the >>>>Alpha-Beta Algorithm" on his page of publications >>>>(http://www.cs.ualberta.ca/~mburo/publications.html) as well as a follow-up >>>>article "A.X. Jiang and M. Buro, First Experimental Results of ProbCut Applied >>>>to Chess", Proceedings of the Advances in Computer Games Conference 10, Graz >>>>2003. >>>> >>>>For new programmers looking for material, this is certainly one, plus it might >>>>be added to the links in the Computer Chess Resource Center. >>>> >>>> Albert >>> >>>To me, ProbCut just seems wrong. How can you throw out an 8 ply search based on >>>a 4 ply search and expect to get things to work, unless your margin is just >>>huge? (Null move is obviously completely different here). >> >>i suppose this depends on the game. e.g. checkers is much more benign in terms >>of evaluation - you can hardly misevaluate a position seriously if you simply >>count material. if you have won a man, you win the game (there are some >>exceptions of course...). => using probcut there makes a lot of sense. >>for chess, i don't see why it shouldn't work at all. of course nullmove is >>different, but both are methods to realize when you can stop wasting your time >>on useless positions. i'd say probcut is much closer to the human way of >>reasoning than nullmove. when i play a game of chess i stop searching at some >>point and evaluate the position, because i think it's safe to do so. i never >>think "now if the opponent could make two moves in a row....". > > Actually, I think we do sort of null move. In a certain complicated position, >I analyze a line, see I win material, then stop analyzing and ask myself "can my >opponent threaten me anything?". Maybe he can push a passed pawn. I let him play >again (assuming it's my turn in the final position) and do a quick search to >verify he can't hurt me. > Not exactly a null move, but a similar idea. hmm, perhaps... i don't usually think in impossible lines, which is why i thought probcut would be closer to how i think. but i know what you mean, there is an aspect of that too! cheers martin > José C. > > >>probcut will work on the majority of positions where one side has bludered >>material. to get it working for the cases where one side sacced material for a >>deadly attack is going to be the problem! >> >>cheers >> martin
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