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Subject: Re: New (?) search enhancement idea

Author: James Swafford

Date: 20:15:17 06/07/99

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On June 07, 1999 at 19:58:45, Heiko Mikala wrote:

>
>Hello Peter!
>
>
>On June 07, 1999 at 19:34:04, Peter Kappler wrote:
>
>>Heiko,
>>
>>What you are describing is very similar to "Enhanced Transposition Cutoffs",
>>where you test to see if any of the moves in your movelist leads to a position
>>which has a score in the hashtable that can cause a cutoff.
>
>Yes, I know :-)
>
>Actually, Enhanced Transposition Cutoffs and some thinking about "what can I do
>(cheap and fast) to avoid searching moves" gave me the idea to this draw test.
>
>To be honest, I've never tried Enhanced Transposition Cutoffs. I might do now,
>because these two things are really very similar. I guess, they might complement
>each other, because you might find draws, which are not (yet) in the
>transposition table.
>
>
>Greetings,
>
>Heiko.

Hi Heiko,

I have never tested this, but I have a gut feeling.
My gut feeling tells me that the theory works for ETC
because most, or at least many positions are in the
trans ref table(s).  (I wonder - is there a direct
correlation between time saved w/ ETC and trans ref
table size?  It the gain linear?)

I think your disappointing results may stem from the fact
that most moves do not lead to drawn positons, so it's
just extra overhead.  An interesting idea would be to
try to identify certain kinds of positions that this
test may help, and set a switch to test only in those kinds
of positions.  (Where stalemate is likely, or only
a few pieces remain...)

You're thinking, though, and that's great.  One of the
things I've learned the hard way is not to rely on
"gut feeling."  Test, test, test.... :-)

Good luck.  If I have some time on my hands in the future
I may give this a try.  Unfortunately now is not the best
time.

--
James




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