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Subject: Re: Best Move in Hash Table Question

Author: William Bryant

Date: 16:24:50 01/20/99

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>
>IE I have a variable (array) hash_move[ply].  When I call HashProbe() if it
>gets a signature match it copies the best move to hash_move[ply] while it is
>checking the draft and so forth.  If the lookup is useless, search calls
>NextMove() to choose the first move, and the one I try is hash_move[ply]
>(making sure it is still a valid move here). And I get to do this _before_
>I generate any moves at all...

What advantage is there to making the hash move 'before' preparing the
move list for this position.  If it fails high, then I realise that a move list
is not needed, but if it fails low or returns a new alpha score, you will still
need to search the rest of the legal move of this ply, right?


Also a few last quick questions.

If a current position has no legal moves (checkmate or stalemate), is the
mate value stored in the hash table as an EXACT score?

When a position leads to a draw by 50 move rule, the return value will be 0, but
since arriving at this position by a different route may not create a 50 move
draw, do you store the positional evaluation score in the hash table even though
you are returning a value of zero?

As always, I greatly appreciate you assistance.

William
wbryant@ix.netcom.com




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