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Subject: Re: finding when a move is obvious.

Author: Tony Werten

Date: 03:12:29 04/14/04

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On April 14, 2004 at 00:26:34, Eric Oldre wrote:

>After you find the 1st "good" move don't you narrow the alpha beta window so
>that you don't know how much worse the 2nd move is, only that it is not as good
>as alpha?
>
>Or do you not narrow the window at the root node? that seems like it would
>greatly expand your search tree.
>
>or am i missing something else?

Before search you check if the last move is a capture. If so you set
maybe_easy_move flag.

When searching, you do the normal search for the first move, check some extra
conditions and then where you normally set the window:

alfa=best_score
beta=alfa+1

you squeeze between

if (maybe_easy_move) then dec(alfa,2_pawns)

and add somewhere

if (search_score>=beta) then maybe_easy_move=false

and

if (after_some_time) & (maybe_easy_move) then you make the move.

Tony

>
>
>On April 14, 2004 at 00:09:24, Robert Hyatt wrote:
>
>>Simple idea:
>>
>>a move is "easy" and can be made after using less than the planned time limit if
>>and only if
>>
>>1.  estimated score for first root move is way higher than the second move.  IE
>>say 2.00 better.
>>
>>2.  This is a recapture.  IE opponent just captured a piece of ours and we are
>>recapturing on the same square.
>>
>>Other types of "easy" moves have higher risk to stop the search early...
>>
>>
>>>
>>>Thanks,
>>>Eric Oldre (new chess programmer)



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