Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Hash tables question

Author: Robert Hyatt

Date: 06:45:20 11/24/97

Go up one level in this thread


On November 24, 1997 at 01:35:38, Komputer Korner wrote:

>Now that we have your word that everyone uses some sort of replacement
>strategy when the hash table fills up,  doesn't this mean that Chris
>Whittington's description of the program acting like a drunken sailor
>when the hash table is filled, a bit of an inaccuracy, thus the results
>of the Korrespondence Kup are valid?
>On November 21, 1997 at 12:34:26, Robert Hyatt wrote:
>
>>On November 21, 1997 at 11:06:15, mike cooter wrote:
>>
>>>In Fritz 5 when I set it up to think on infinite level, once my
>>>hashtables fills up to100 percent, is the computer still thinking on
>>>what is the best move? If it is, then what is the hash tables for?
>>
>>they are used to speed up the search.  However everyone uses some sort
>>of replacement strategy when the table fills up, so that it continues to
>>help the search, although at a somewhat reduced effectiveness...

As I've said all along...  long searches certainly run into a sort of
"wall"
where the branching factor seems to go up by some amount...  But it
doesn't
mean the programs play blindly or stupidly...

I don't know who uses what replacement strategy.  Don Beal wrote a paper
a
few months back testing the algorithm I used in Cray Blitz vs a simple
two-
level replacement strategy like I now use in crafty.  For cases where
saturation
became an issue, the old Cray Blitz algorithm was better.  But we aren't
talking
about 10X faster, or 5X faster, which is a common misconception.

Someone posted some results here that showed Crafty slowing by 2x when
it
"hit the wall".  2x is significant, but hardly critical at
correspondence
depths...




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.