Author: Bob Durrett
Date: 14:26:26 11/20/00
Go up one level in this thread
On November 20, 2000 at 14:30:04, Daniel Kang wrote: >On November 20, 2000 at 13:13:21, Bo Persson wrote: > >>On November 20, 2000 at 12:14:57, Bob Durrett wrote: >> >>>On November 20, 2000 at 11:55:10, Bo Persson wrote: >>> >>>>On November 20, 2000 at 11:06:46, Bob Durrett wrote: >>>> >>>>>Would it be possible to evaluate a position so well that only one next move >>>>>would need to be considered? In that case, "selective search" would not involve >>>>>any selection at all [i.e. nothing to chose between]. The "selection" would be >>>>>done during the position evaluation. In the limiting case, only ONE line would >>>>>need to be evaluated, except in the cases when two or more moves were found >>>>>[during the position evaluation] to be of equal value. >>>> >>>>If it was possible, you would have solved chess! :-) >>>> >>>>Just let the program run from the start position, and see if it comes up with >>>>e2-e4 or d2-d4 as the optimum opning. Repeat for 40 plies and you end up in a >>>>check mate for white (or a draw??). >>> >>>You are assuming that one or the other of 1.e4 or 1.d4 is the better move. >>>Maybe not a valid assumption! >> >>Of course we don't know for sure, as the evaluator isn't finished yet. I would >>be *very* surprised if it was 1.a3 instead. >> >>>Incidentally, the position evaluation software may have to declare two or more >>>moves "equal" if they appear to be reasonably close. How "reasonably" would be >>>defined in this case would be up to the programmer. >>>> >> >>My point was supposed to be that the current programs already *do* this >>evaluation, by doing a lot of calculations for each potential move from the >>position. The calculations are called "search". > >I'd also like to add that this characteristic (looking at all moves rather than >blindingly following their intuition to limit the search to a couple of good >moves) is probably a strength of computer programs rather than a weakness. The >reason why humans rely on pattern matching rather than searching for move >selection is because their searching capacity is severely limited, not because >searching is an inferior method. In some sense, a human brain is a massively >parallel super-duper fault-tolerant computer specialized for pattern >recognition, yet to be matched in power by silicon-based number crunchers. I >just don't think it's a sound idea to imitate the human process, when current >methods have already yielded programs that outplay almost all humans, with >machines far less sophisticated than brains of even the dumbest humans. > >Dan. A tree can get extremely large very fast if you look at all possible moves from a position. Even if you were to look only at two moves for each position, think about the size of 2**n where n is the number of half-moves. If that is OK with you, then think of what happens to 3**n, 4**n, etc. As the number of moves gets larger, the tree explodes. Hence people's efforts to prune and selectively search. The problem is real!
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