Author: John Coffey
Date: 16:08:53 10/29/98
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On October 28, 1998 at 08:58:05, Robert Hyatt wrote: >On October 27, 1998 at 01:35:31, James Robertson wrote: > >>On October 26, 1998 at 17:15:56, John Coffey wrote: >> >>>On October 26, 1998 at 02:10:37, vincent dichiacchio wrote: >>> >>>>my question is how programs deal with the possibility of a great non capture >>>>move in the middle of a series of captures in a quiescence search. if the >>>>quiescence score ignores that non capture, the score is faulty at best. >>>>vince >>> >>> >>>How is Q search any different from extending captures out? Could someone >>>please define Q search for me? >>> >>>John Coffey >>The q-search is just that; a minimax search that only evaluates capture moves >>(maybe also pawn pushes or check evasions). This is a major simplification, as >>there are several big differences from the normal minimax search. >>I am still trying to think of how to explain them....... um...... er..... can >>someone like Bob or Ernst help here? >> >>James > > >the two main differences between normal search and q-search: > >1. in the q-search, we initialize alpha to Evaluate() which gives us the >opportunity to either (a) make any move we want to or (b) stop the search at >this point and take the static evaluation (this is the "stand pat" option). > >The point is that you might not have a good capture to make. This lets you >say "should I stop the captures here and accept the score/material balance on >the board, or should I capture something here?" > >2. in the q-search we generally exclude some moves. IE in crafty I exclude >all non-captures right up front. Then I exclude captures that seem to lose >material based on the SEE procedure. > >Other than those two things, they are similar. No real need to do repetition >checking in the qsearch if you only do captures, for example. Perhaps a few >other things like the 50-move rule also don't apply, depending on what you >exclude... Does Q-search come before or after the capture search? I.e. do you do a full search, and then extend that with a Q seach and then extend that will a capture search? Or are they the same? John Coffey
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