Author: Robert Hyatt
Date: 08:41:28 02/24/04
Go up one level in this thread
On February 24, 2004 at 11:21:37, martin fierz wrote: >On February 24, 2004 at 11:14:00, Robert Hyatt wrote: > >>On February 24, 2004 at 09:27:26, martin fierz wrote: >> >>>On February 23, 2004 at 11:14:28, Robert Hyatt wrote: >>> >>>>On February 23, 2004 at 07:02:59, martin fierz wrote: >>>> >>>>>aloha, >>>>> >>>>>i have a question about pins. pins are a rather important feature in chess; some >>>>>of them are not so bad, some are deadly. i just happened to chat briefly with >>>>>anthony cozzie on ICC, and he said he didn't do any pin detection. i detect >>>>>pins, but i don't evaluate whether a pin is not so bad or deadly. my questions >>>>>are: >>>>>-> are you detecting pins in your program? >>>>>-> if yes, do you try to distinguish between different pins? >>>> >>>>No and No. I don't do it as I have not found it very important. IE with the >>>>depth I hit today, if a pin is important, the search can go deeply enough to >>>>discover this without much trouble. 20 years ago I was definitely evaluating >>>>pins, as hitting 5-6-7 plies is not deep enough to see the consequences of a >>>>pin, whereas todays 12-16 plies in longer games is more than enough in most >>>>cases. >>> >>>interesting - and a possible explanation why i believe i need them. muse >>>searches something like 1-2 plies less than crafty on equal hardware (meaning >>>single-processor hardware of course...), and i play blitz matches. so i'm >>>getting something in between of your 5-7 and 12-16 plies; meaning that i am >>>closer to needing pin detection than you are :-) >>> >>>cheers >>> martin >> >>You are also in the danger-zone for null-move R=2 and R=3 as well, at those >>depths. If you look at the comments in main.c in Crafty, you will see how many >>times I tried R=2 from 1994 to date, and how many times it failed, until the >>depth reached a point where null-move didn't hide too many tactics... >> >>Depth is definitely part of the formula, and the deeper we go, the more things >>change in unexpected ways... > >i'm using adaptive R=2 / R=3; R=3 at depths > 6. i once tried using R=3 all the >time with bad results. i know i still have to work on my search a bit :-( > >cheers > martin Just don't forget to go back and re-test it from time to time. Things change as your search gets better, the hardware gets faster, etc... I did R=2, R=1, R=2, R=1 no telling how many times before R=2 finally worked better than 1 for me. :) > > >> >>> >>>>There are exceptions, but the question has to be "is the cost of doing this >>>>offset by the playing strength increase?" I believe that at least for my >>>>program, the answer is "no". >>>> >>>>YMMV of course. >>>> >>>>> >>>>>cheers >>>>> martin
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