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Subject: Re: History Heuristic

Author: Gerd Isenberg

Date: 13:31:00 03/16/04

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>>>>>>>I principally agree with GCP here. I do not understand how in certain software
>>>>>>>HH can work. Must be a bug in their move ordering IMHO.
>>>>>>
>>>>>>If you can't make them work, why do you reply to his post?
>>>>>>
>>>>>>-S.
>>>>>
>>>>>
>>>>>Ignorance.  Unabashed ignorance...
>>>>>
>>>>>What else?
>>>>>
>>>>>HH works just fine.  Of course if Vincent can't get them to work, then it is
>>>>>impossible that they will work for anybody.  "proof" enough??
>>>>
>>>>Yes, and this time the poster even gets to contact him personally for more
>>>>information on how NOT to make them work!
>>>>
>>>>I admit I can see his point, precious secrets _like that_ are not to be posted
>>>>in a public forum :)
>>>>
>>>>-S.
>>>
>>>
>>>none of his "precious secrets" should be posted...
>>>
>>>:)
>>
>>Just try this - after the end of a 3 min search from a fairly complicated middle
>>game position (like for example - Nxh6 nolot position) , print out the history
>>values.
>>
>>You will see the junk that is contained in the table.
>
>Do you understand what this "junk" means???
>
>I don't see how it can be called "junk".  The data simply reflects how useful
>each move was in the search done.
>
>>
>>If you seriously expect much of information to be obtained from this for move
>>ordering - I dont know what to say.
>
>I feel the same, except in an inverse way.
>
>History works for me.  Turn it off and the tree gets bigger.  A couple of
>samples:
>
>          nodes w history       nodes wo history
>pos1         38,151,984             42,728,175
>pos2        167,685,660            184,874,107
>pos3         81,663,363            124,704,814
>
>Now if you believe those three randomly chosen positions are worse because of
>"random junk" feel free.  The tree size is _remarkably+ smaller on pos 3, and
>significantly smaller on the other two...


Ok, i may find three positions too where some additional random move ordering
results in similar smaller trees ;-)

I believe in HH too, still use byte arrays with some degree of saturation.
I count overflows for each color if 255.
I age them by div two if some amount of overflows occurs.
I use higher increment for mate threads if < 200.
I use countermove or butterfly heuristic too and of course killers.
With depth left > 3 i use more sophisticated move sorting.

In my next generation approach i will try move-index in a range of about
0...4000 (quite moves per side) to distinguish not only between coordinates but
pieces too. Curious about the infuence on HH with those indices.

<snip>



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