Author: chandler yergin
Date: 02:35:57 10/11/05
Go up one level in this thread
On October 11, 2005 at 05:11:57, Uri Blass wrote: >On October 11, 2005 at 04:39:01, chandler yergin wrote: > >>On October 11, 2005 at 04:08:58, Bruce Moreland wrote: >> >>>On October 10, 2005 at 23:37:41, chandler yergin wrote: >>> >>>>http://chess.verhelst.org/1997/03/10/search/ >>>> >>>>"Tree search is one of the central algorithms of any game playing program. The >>>>term is based on looking at all possible game positions as a tree, with the >>>>legal game moves forming the branches of this tree. The leaves of the tree are >>>>all final positions, where the outcome of the game is known. The problem for >>>>most interesting games is that the size of this tree is tremendously huge, >>>>something like W^D, where W is the average number of moves per position and D is >>>>the depth of the tree, Searching the whole tree is impossible, mainly due to >>>>lack of time, even on the fastest computers. All practical search algorithms are >>>>approximations of doing such a full tree search." >>> >>>It's true for chess. Some aspects are not true for tic-tac-toe, and some others >>>are not true for other games that aren't like chess. >>> >>>I don't know where you are going with this. It's possible to make a lot of >>>assertions about chess programs that people will agree with unless they don't >>>understand the assertion. That the chess tree is too big to search to its >>>limits with any sane hardware is obvious. Someone might mention quantum >>>computers here, but that doesn't fall into the category of sane. >>> >>>bruce >> >> Thanks Bruce for your response... >>Where am I going? I'm trying to get a consensus of opinion before I embarrass >>myself.. But on the other hand I'm used to that. >>No, this is strictly about chess.. not Tic tac toe or other games. >>I expected a negative response from Uri, and he has Posted that Programs do not >>evaluate every move in a position. > >programs do not evaluate every move in a position that they search >and it does not contradict your post. > >programs have pruning rules. >It is written also in your post that >"Searching the whole tree is impossible, mainly due to >lack of time, even on the fastest computers." > >>Well, you know that is not true. >>Rather than have a long thread and dialog with him, I was hoping that other >>Programmers would agree about the Tree ..search function analysis mode etc. >>I think that is a given, so we'll start from here. >>It should be obvious that he who runs the fastest wins the race. >>The Program/Engine that searches the deepest & faster in the alloted time, >>finds the 'best' moves. >>Would you agree? > >No > >A program may search deeper but still lose because of inferior evaluation. No, We disagree 100% The Program truly does evaluate 'every' possible move in any position! It ranks them in order of the highest return from the Alpha Beta & Mini/Max algorithim. The centipawn eval is based only on the static positional factors programmed in. The program that searches the deepest in the alloted time will find the better moves. I don't understand why you don't understand this! > >Searching deeper is a clear advantage but computer chess is not only about >searching deeper. It's exactly about searching deeper! > >Uri
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