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Subject: Re: HashTable upper_bound worthless ?

Author: Carmelo Calzerano

Date: 00:59:15 02/15/01

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On February 14, 2001 at 12:37:52, Larry Griffiths wrote:

>On February 14, 2001 at 10:11:53, Carmelo Calzerano wrote:
>
>>On February 14, 2001 at 09:35:58, Larry Griffiths wrote:
>>
>>>Carmelo,
>>>
>>>I will dink around with the hash table some more and see if I can find a bug
>>>somewhere.
>>>
>>>Is this Fine 70?
>>>
>>>[D]8/k7/3p4/p2P1p2/P2P1P2/8/8/K7 w - -
>>
>>Exactly ;-)
>>
>>Bye,
>>Carmelo
>
>Ok Carmelo,
>
>I did find a bug in my hash code and am getting upper_bound cutoffs now.
>I owe you one since I was about to give up on the hash table for a while.
>I ran the Fine 70 position using a 16meg hash table.  My hash tables are
>28 bytes in size.
>
>My program goes 17 plys in 18 seconds without the hash table,
>and 19 plys in 6 seconds with the hash table.

There is still something to fix then; with HT you should be able to reach
at least 25 ply in a few seconds on Fine70.


>I noticed that Hardly any of the 16meg hash table was used.  I am only using 1
>slot per hash key, and maybe if I add/look at the next 8 slots I can get some
>more entries in the hash table and go deeper on plys.  I do not know if I will
>be able to get 33 plys (impressive).

Oh, that's not impressive at all: it's a normal value on Fine70, where all
pawns are blocked and only kings can move. Nearly every program which uses
HT should be able to do the same (or better). :-)

If your can't, maybe you still have some bugs or a really bad key
distribution...


> I found a bug in my hash table code a few
>days ago that might explain why my program was making bad moves with my old hash
>table code.
>
>Thanks so much for your help.

You're welcome :)

>By the way, what is your chess program name?

The name is Leila; it's not yet released, but I plan to freely distribute
it after the end of the FIEC (the first italian engine online championship,
which is running on FICS).

Bye,
Carmelo



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