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Subject: Re: Match Junior 6a - Tiger 12e (40 in 2 hr, 20 in 1hr) completed...

Author: Dave Gomboc

Date: 10:02:10 03/28/00

Go up one level in this thread


On March 27, 2000 at 23:20:50, Robert Hyatt wrote:

>On March 27, 2000 at 11:15:23, blass uri wrote:
>
>>On March 27, 2000 at 09:53:57, Ed Schröder wrote:
>>
>>>On March 27, 2000 at 09:06:01, Robert Hyatt wrote:
>>>
>>>>On March 25, 2000 at 23:13:49, Tina Long wrote:
>>>>
>>>>>On March 25, 2000 at 14:28:13, James Robertson wrote:
>>>>>
>>>>>>On March 25, 2000 at 13:41:28, Roger wrote:
>>>>>>
>>>>>>>Would tablebases for Tiger have changed this result at all?
>>>>>>>
>>>>>>>Roger
>>>>>>
>>>>>>Maybe a quarter of a point.... My experience with tablebases is that if the
>>>>>>program is moderately smart it doesn't benefit tremendously from them.
>>>>>>
>>>>>>James
>>>>>>
>>>>>Ed Schroder said about 6 months ago that Tablebases were worth about 10 points
>>>>>on the SSDF scale.
>>>>>
>>>>>I'm 70% sure he said that! I'm 100% sure that Ed said once that something was
>>>>>worth very little rating points.
>>>>>
>>>>>I'm glad I could add some real detail to this discussion.
>>>>>
>>>>>Tina Long
>>>>
>>>>
>>>>Ed is wrong there.  it is _amazing_ how many comp vs comp games end up in
>>>>krp vs kr, with the side without tablebases losing most of those.  There are
>>>>other endings too (KQP vs KQ, see for example crafty vs nimzo in the ICCT
>>>>tournament last month).
>>>>
>>>>The wrong way to test this is to play A with, vs A without.  the right way to
>>>>test this is A without vs B without, then A with vs B without.  But A ought to
>>>>be reasonably close to B without tablebases...
>>>
>>>Tablebases have a great future no doubt. But what is available at the
>>>moment (4-5 pieces) its value for Rebel is not more than 5-10 elo I
>>>would say because:
>>>
>>>a) most cases are simply covered by chess knowlegde;
>>>
>>>b) the loss of speed during search because of all the
>>>disc access.
>>
>>I do not think that b is right because you save time by not searching positions
>>of 5 pieces.
>>
>>disc access is relevant only after a capture that leads to 5 pieces on the
>>board.
>>My simple logic says that if you search n plies forward then you can decide to
>>call tablebases only after a capture that leads to 5 pieces and only if the
>>caprure is at distance of n-d plies from the root when d is the minimal numner
>>that searching d plies forward is slower than calling tablebases.
>>
>>
>
>
>
>That is all correct.  Disk access is _not_ a problem.  It doesn't slow me
>down enough to be a problem at all, and the gain more than offsets the
>I/O time...  and if you cache stuff right, and hash the results right, the
>penalty drops to almost nothing for most positions...
>
>And the gain...  :)

Disk access isn't a problem _now_ in Crafty, but it was for a while until you
tuned the implementation, right?

Dave



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