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Subject: Re: Hash and first Fail High

Author: Uri Blass

Date: 15:51:58 08/14/03

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On August 14, 2003 at 18:37:16, Gian-Carlo Pascutto wrote:

>On August 14, 2003 at 18:32:01, Uri Blass wrote:
>
>>1)If your first move did not fail high than it is better to have bad order of
>>the rest of the moves because if you have bad order of the rest of the moves >you have good chances that the first move is going to fail high against them.
>>
>>If you have good order of moves than the you get no points for the fact that
>>your second move failed high.
>
>It's late in here, and I don't get this at all.
>
>I don't understand a thing of what you are saying, and what I do understand,
>looks wrong.
>
>--
>GCP

ok I will try to explain at least one point
Let assume that you start from a position when alpha=0 beta=1

you start the search with bad move for white and good move for black
omagine that black has a mate threat that there is only one way to defend
against it and imagine that you failed to find the defence in the first move
when you searched
1.e4 Qxh2#
now you have one defence against Qh2# namely Rf2 but if you choose Rf2 as a
second move you get no first fail high from it.

Suppose that you try bad moves for white 1.e3 Qh2# 1.d4 Qh2# for every wrong
move Qh2# cause a cutoff so your order of moves looks better relative to the
case that you never calculates these lines because the second move(Rf2) produce
a cutoff.

Note that I did not try to calculate percentage of fail high because it seemed
to me wrong because of the reason that I gave now.

Uri



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