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Subject: Re: To Bob Hyatt: Ply Number Versus Rating

Author: Robert Hyatt

Date: 06:49:32 01/05/99

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On January 05, 1999 at 00:29:08, Shane Booth wrote:

>On January 04, 1999 at 18:06:41, Robert Hyatt wrote:
>
>[lots snipped]
>>I'm not sure about depth... but I'd guess that in blitz games, the middlegame
>>depth is in the range of 9 plies, maybe 10 (of course in some wild positions it
>>might only be 8 or so as well).
>>
>>As far as what does a ply do for crafty?  hard to quantify, but clearly every
>>ply is important.  IE the p6 was about 2.5X the P5/133 I used and its
>>rating took a big jump.  The  quad p6 gave another factor of 3 and another
>>noticable jump, and now the quad xeon (which ramps out at about 2x the quad
>>p6, roughly) is another noticable jump.  So far, I see *no* indication that
>>another ply won't produce a better search result...
>>
>>what we need is for someone to organize a crafty vs crafty tournament, no
>>pondering, and try one with sd=4 against sd=5,6,7,8,9,10 (at least).  Then
>>do sd=5 vs 6,7,8,9,10, then sd=6 vs sd=7,8,9,10 and so forth.  That would
>>give a good graph of what another ply (or more) is worth for crafty...
>
>I have been running a similar experiment recently, playing Crafty 15.20
>against CM4000 using search depths of 1-10 for Crafty and 1-8 for CM4000.
>I've only played 300 games so far (so 30 games for each search depth
>for Crafty), so the statistical error in the results is still quite high.
>Anyway, here's what I have so far: (Fixing the rating of 1 ply Crafty
>arbitrarily to 600)
>
>Depth  Crafty  CM4000
>1      600     655
>2      793     1012
>3      1072    1401
>4      1365    1422
>5      1575    1711
>6      1677    1791
>7      1697    2027
>8      1940    2198
>9      2076
>10     2242
>
>Crafty has learning turned off, and games between the same opponents
>are never played with the same opening.
>
>Regards,
>Shane


This test isn't really very good, because you have two variables in your
mix, rather than the one we would normally like in a scientific experiment.

IE it is quite obvious that chessmaster and crafty do a totally different sort
of search, when you try having both search to depth=8 for example, because
crafty will get there _way_ faster.  Which means it is doing less work (which
probably means fewer extensions).  Perhaps a better way of doing your test would
be time-based instead.  1 sec vs 1 sec, 1 sec vs 2 secs, and so forth.  But you
still have two different programs. which means still two variables.

and using crafty vs crafty has an additional problem, in that by my test
results, using two identical programs means that any minor change to one will
be greatly exaggerated in the game results.  IE giving one 2x more time will
likely produce results that are better than expected for the side having 2x
more time.



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