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Subject: Re: A move to search 2nd... Keep in the trans table?

Author: Pham Hong Nguyen

Date: 18:26:20 07/21/04

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There are two cases:

1) Second best move of the root. Dr. Hyatt has a very interesting mechanism for
this case. After each iteration, he sorts root moves by seached nodes. Thus, the
second move will have the second searched nodes and have more chance than the
rest to become the best move.

2) Second best move of any node. Someone has developed already an idea to store
not only the best move but the pv of this node to the hash table. However, the
hash size will become so large but the gain is still little. This also depends
on the engine. You may try.


On July 21, 2004 at 16:55:07, Eric Oldre wrote:

>lets say you are searching a position with iterative deepening.
>at depths 3,4,5 it finds a best move of Qd3. then at depth 6
>the best move changes to c4.
>When you start searching to depth 7, you clearly would want the
>first move you search to be c4, and this shouldn't be a problem
>if your transposition tables are working right. Since the best
>move should be stored in it.
>however, a good move to try 2nd would be Qd3, but your transposition
>tables aren't going to let you know that, at least not in the implementations
>that I have normally heard about.
>I was thinking that one way to overcome this would be to keep 2 "best" moves
>in the trans table. one to try first, and one that was a best move, before
>being replaced by a deeper search.
>Are other people doing this? or have you discovered that the cost is greater
>than the benefit?

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