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Subject: Re: Hash tables vs alpha/beta

Author: Peter Fendrich

Date: 13:31:50 01/17/00

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On January 17, 2000 at 10:49:05, Vincent Diepeveen wrote:

>On January 17, 2000 at 10:23:13, Peter Fendrich wrote:
>
>>When searching the hash table, I've detected basicly 9 different states.
>>The value from the table is a Lower (L) or Upper (U) bound or Inside (I) it's
>>A/B-window.
>>For each of these we have 3 cases:
>>1. value <= current Alpha
>>2. value >= current Beta
>>3. current Alpha < value < current Beta
>>
>>Combining it all we have: 1L, 1U, 1I, 2L, 2U, 2I, 3L, 3U and 3I
>>
>>For now I'm interested in case  and 3U.
>>When we have 3L, we know that the table entry is the lowest
>>possible value and that the current Alpha is lower. To me it seems
>>reasonable to set current Alpha = table value.
>>For 3L this will be: current Beta = table value.
>
>Oh i hear a lot of dudes inventing this. It never worked for me.
>I don't do it in DIEP. There are more difficult ways to ask for
>trouble...
>
>>That doesn't work well with my program which has a PVS-based alg.
>
>right. simple insight will provide us also why.
>
>suppose your bound from hashtable is n ply search based. Now you
>search at ply = n-i ply where i > 0.

I don't follow you here, what's i? depth?

>
>Probably more reasons are there than this...

//Peter



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