Author: Nobuhiro Yoshimura
Date: 22:36:59 10/25/98
Go up one level in this thread
On October 25, 1998 at 19:34:32, Robert Hyatt wrote: >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... In a position like: 0) in q-search node 1) WTM 2) white queen in danger 3) a black pawn in danger In such postion, do you only generate a capturing a black pawn? If so, the postion will be evaluted as a very bad position( losing queen). Are you saying that if we search deep enough, we donot get a bad side effect eventhough such position might occurs during the search?
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.