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Subject: Re: What is tactics ?

Author: Uri Blass

Date: 12:37:59 02/06/03

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On February 06, 2003 at 14:35:18, Tom Likens wrote:

>On February 06, 2003 at 13:35:39, Matthias Gemuh wrote:
>
>>
>>
>>What makes a program tactically strong ?
>>
>>- right extensions ?
>>- search depth ?
>>- strange eval and eval weights ?
>>- sound pruning ?
>>- nps speed ?
>>- or simply luck and chance ?
>>
>>/Matthias.
>
>Hello Matthias,
>
>I found an interesting, and not very obvious (at least to me),
>result as I have continued to work on my chess program.
>It has become tactically stronger as I've added more purely
>positional knowledge.
>
>I believe that the better evaluation function is shaping the
>tree (mainly, via the beta cutoff at the beginning of the
>quiescence search) so that the program is wasting less time
>going down unproductive branches.  Because of this it is
>searching deeper and is more tactically aware.
>
>You'll find that as you add code to recognize various patterns
>that can occur (such as rook pawn and wrong color bishop
>endings) that the program will become better both positionally
>and tactically.
>
>regards,
>--tom

It is dependent on the program and the knowledge that you add.

If you add knowledge and your program search x/10 nodes per second instead of x
nodes per second then the fact that you need less nodes to get solutions to
tactical problems does not mean that you are stronger in tactics.

I also know examples when adding knowedge did the program weaker in tactics for
other reasons.

Rebel with knowledge=500 without lazy evaluation is weaker in tactics than Rebel
with lazy valuation and Rebel with knowledge=500 not only search slower but also
needs more nodes to get the same depth.

In the case of Movei I found that the biggest improvement in tactics was not a
result of adding knowledge in the evaluation but of improving the search rules.

Uri



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