Author: Robert Hyatt
Date: 14:36:01 03/26/01
Go up one level in this thread
On March 25, 2001 at 12:21:56, Vincent Diepeveen wrote: >On March 25, 2001 at 09:37:09, Robert Hyatt wrote: > >>On March 25, 2001 at 03:51:02, Pham Minh Tri wrote: >> >>>Hi, >>>I am wondering why we do not search checking moves (moves check opponent king >>>but do not capture) in qsearch function. I think they are not ?quiescence? and >>>should be searched as capture moves. Does anyone try them? >>>Thank very much for any explanation. >>>Pham >> >> >>I have two answers: >> >>1. I did q-search checks in Cray Blitz. I also did them in early versions >>of crafty as you can see in the comments in main.c... >> >>2. I removed them a _long_ while back in Crafty. >> >>Here is my analysis: If you do q-search checks, you will find some tactical >>lines significantly quicker, obviously. But since you are searching much >>deeper along lines with lots of checks, overall you have to search less deeply >>along non-checking lines, since you can only search a fixed number of nodes in >>a fixed unit of time. > >>You have to make the following choice: either (a) find tactical shots that >>depends on checks quicker, but give up some positional skills as positional > >As doing checks in qsearch finds tactics 4 ply sooner for me, sometimes >even zillions of plies as i try unlimited number of checks in many cases >in qsearch, for me it's quite easy to go for a here without ever considering >b. Idem for many commercial programs. I wouldn't begin to argue here either way. But if you find tactics 4 plies sooner, how much depth do you lose overall because of those checks? Is it worth the lost depth to see tactics sooner? If I lose enough games due to this, I will certainly implement it once again. But I haven't, so far, and I like the 14 ply depths in normal middlegame positions. That covers up a lot of potential positional mistakes.. > >>moves will be searched less deeply; (b) find tactical shots slower, but then >>search deeper in positional cases and find positional threats your opponent >>won't be able to see because the checks prevent him from getting deep enough >>to see it. >> >>I like the non-check approach because (1) I can search deeper overall, and in >>non-tactical positions this pays off well; (2) the q-search code is much >>simpler, which makes it even faster since so much of the total time is spent >>there; >> >>Of course, everyone should try it themselves to make sure they get the same >>results I get. I do know of several programs that use this approach with >>great success. Note that I don't particularly think much of the idea of >>searching checks very deeply but overlooking all of the _other_ kinds of >>tactical moves you might include in the q-search. Pins. Attacking overloaded >>pieces. etc... >> >>By keeping the q-search simple, the normal search handles more of the nodes, >>and since that part of the search includes _everything_ you might be tactically >>stronger by not overlooking something.
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.