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Subject: Re: Hash and first Fail High

Author: Ralf Elvsén

Date: 12:48:03 08/15/03

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On August 15, 2003 at 04:57:07, Peter Fendrich wrote:

>On August 14, 2003 at 21:43:42, Ralf Elvsén wrote:
>

>>
>>Hello
>>
>>I haven't done any chess programming in over a year now (cured :). As you say
>>yourself below, this could be a statistical fluctuation. But I'm with Uri here:
>>I remember implementing a special improvement in move ordering in my program.
>>It worked fine, the time to search to a certain depth decreased. However, the
>>measure you call 1FH got worse. I made the same interpretation as Uri, namely if
>>you produce crappy moves at one ply you can will get a lot of FHs at the next
>>and your statistics looks fine :) I actually had a more refined statistic then
>>you:
>>I had 1FH for each ply, it probably was opposite effects for the last ply and
>>the ply before that (can't remember for sure though) but there are more nodes
>>closer to the leafs and they dominate the statistics. Hope I made myself clear,
>>it's late at night...
>>
>>After that I didn't care much about this number anymore.
>>
>>Ralf
>
>You think you're cured? Why are you engaged in this discussion then ... :-)

Woke up at night and couldn't sleep. That is when you do the most useless
things :)

>I bet you'll start again soon...

Nope. Last summer I wasted a lot of time on chess programming. What did I get?
A program ranked nr 200 in the world? :) None of my brilliant ideas worked
as I thought they would. This summer I have been skydiving instead. Much better
:)

>
>Yes, Uri has a point. I agree on that but not necessary in this case. Hash moves
>are used as first moves only (in my program). Removing the hash moves should
>worsen the 1FH that is clearly defined as performance of the first move only.
>Your example, as you described it in another post, makes sence I think but you
>should get better values in other meassurements. 1FH is only one dimension.
>
>/Peter

Sorry for being a little unclear about what I meant. I wasn't trying to explain
your numbers, just give my opinion on 1FH as a reliable measure of move
ordering.

Ralf




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