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Subject: Re: MTD(f) and storing the PV

Author: Andrew Williams

Date: 12:50:18 07/29/03

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On July 29, 2003 at 14:58:48, Tord Romstad wrote:

>On July 29, 2003 at 05:42:11, Andrew Williams wrote:
>
>>On July 29, 2003 at 05:38:20, Tord Romstad wrote:
>>
>>>I am currently experimenting with MTD(f).  There are still a few bugs left
>>>to fix, but it mostly seems to be working OK now.  However, there is one thing
>>>I haven't been able to figure out:
>>>
>>>Is there an easy way to store the PV in MTD(f)?  Currently I just construct a PV
>>>from the hash table after each iteration.  This works, but is somewhat messy and
>>>inconvenient.  Is there a better way to do it?
>>>
>>>Tord
>>
>>Hi Tord,
>>
>>I do as you do, and extract the PV from the hash table. Some time ago, a guy
>>called Fabien Letouzey appeared here with an alternative suggestion:
>>
>>http://fortuna.iasi.rdsnet.ro/ccc/ccc.php?expr=&subject=&author=letouzey&email=&nr=50
>>
>>I've never tried it.
>
>Thanks.  If building the PV from the hash table is good enough for you, I
>think I'll keep doing it like that myself (with Tony Werten's suggested
>improvements), and take a closer look at Fabien Letouzey's suggestion
>when my mtd(f) is good enough to be usable.
>
>There is still a long way left before mtd(f) works as well as traditional
>aspiration search in my program, but I will continue trying for some time.
>mtd(f) is fun and addictive.  :-)
>
>Tord

Yes. There's just so much scope for experimentation. For example, in Aske
Plaat's online description, he raises and lowers the guess by 1 each time around
the MTD loop. I've never been able to make this work effectively. Far better to
accelerate this. If the score is going up, I add 1 the first time then 2, then 3
etc etc. I think I stop at 7 or something. I can't remember now. The same
applies to when the score is sinking.

Have you read Aske Plaat's PhD thesis? It's available online somewhere and is
very interesting and readable.

AW



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