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Subject: Re: MTD is a big win.

Author: Don Dailey

Date: 18:15:24 07/20/99

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>>But what really  stood out was that I was  expecting the difference to
>>be trivial, after all I was comparing to a good PVS implementation.  I
>>really don't  remember the exact  numbers, but it was  substantial and
>>way too much to ignore.  It was over a 15% speedup.
>>If I used MTD with NO lazy evaluation versus PVS with lazy evaluation,
>>PVS  would be a  win because  lazy evaluation  is a  big win.   If you
>>measure  improvement by  the  number of  nodes  needed to  do a  given
>>iteration then  MTD is  a big  win there is  simply no  question about
>>this, certainly  not with Cilkchess.   Lazy evaluation is a  nodes per
>>second optimization and I have  no reason to believe it would suddenly
>>not work with MTD.  MTD is simply another kind of aspiration search.
>I'm not sure first that I'm understanding why you can't use lazy eval with MTD.
>Is it because you trash your hash table and get search instabilities?  If so,
>that sounds like a serious practical problem.
>I'm not sure why it's fair to factor out lazy eval.  My own goal here is not to
>do the fewest nodes necessary to reach depth D, my goal is to get to depth D in
>the least amount of time.  And if PVS + lazy eval < MTD, I'll take PVS + lazy

I don't I got my point across very well.    I am saying there is no
reason whatsoever that you cannot use lazy evaluation with MTD.  It was
a problem earlier because I did not understand fully what I was doing
but I think the problem is solved now.  So I'm saying that I don't have
a good excuse NOT to use MTD and that you can indeed use lazy evaluation
with no problem.

- Don

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