Author: Robert Hyatt
Date: 16:34:32 10/25/98
Go up one level in this thread
On October 25, 1998 at 18:58:12, Nobuhiro Yoshimura wrote: >On October 22, 1998 at 23:20:10, Robert Hyatt wrote: > >>On October 22, 1998 at 23:04:31, Peter McKenzie wrote: >> >>>On October 22, 1998 at 21:38:29, Fawna Bergstrom wrote: >>> >>>>Well everyone has their opinions on this kind of question--here are a few of >>>>mine. Let's go back to basics: >>>> >>>>Level I: You search full-width to a fixed depth (alpha-beta, iterative >>>>deepening, etc. are all assumed, of course.) Here your evaluator includes both >>>>material and positional factors. Move ordering is critical. First expand >>>>"killer" moves, "interesting" moves and moves that yield a higher evaluation. >>>> >>>>Level II: If you like you can then search beyond that looking at "interesting" >>>>moves such as captures, threats, checks, etc. Don't bother with threats unless >>>>the threatened piece is hanging and/or more valuable than the threatening piece. >>>> You should limit the depth of this second phase or you can skip it altogether >>>>and go straight to level III--it's your call. In level II the evaluator >adjusts >>>>for material only. Personally I wouldn't waste too many plies on Level II. >>> >>>I'm not 100% sure what you mean here, but if you start returning scores from the >>> quiescence search that don't take into account changes in evaluation due to >>>captures effecting pawn structure, and these scores can find their way into your >>>PV, then you're likely to get killed positionally. >>> >> >> >> >>there are things interesting to try here. IE if you only look at winning >>captures, you can probably get away with a positional eval at the leaf node >>that starts the qsearch, and then pass this value along to be modified as >>pieces are captured. >> > >May I ask a simple question ? I am a Japanese-Chess programmer so that >I donot much about the chess programming. In the following postion: > 0) In the q-search node > 1) WTM > 2) a white in danger > >Questions: > 1) Do you generate esacaping moves for the white peice ? > 2) Do you assume that a white piece can esacpe in the stand pat eval? > 3) Is it better to make a "PASS" move ( without depth deductions) > to check whether the black can really gain profit by capturing it? > > >Nobuhiro > > I don't, no. I don't trust the q-search to do this sort of stuff. I only hope I have extended enough already to avoid this problem. (2) yes as my eval doesn't consider pieces that are trapped/hung/etc except for some special cases like a bishop at h2 with a pawn at g3 trapping it... (3) did this in the 1970's and it worked ok... ie "pass" then see what happens, and *then* try to find a move that prevents that from happening... Don't do it today because of the extreme depths we see nowadays...
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