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Subject: Re: Attack tables in QSearch

Author: Volker Böhm

Date: 09:38:25 04/14/04

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Hi,

we (Ralf Schäfer and me) are currently developing a new engine from the scratch
and we have currently implemented the search.
We desided to use 0x88 and attack-tables. The attack-tables are build up
incrementally, also in q-search. Here is why:

1. We are nearly three times faster in implementing attack-tables incrementally
than fully, even with a undo feature.
2. Lots of positions are positions with king in check because of check
extensions. With attack tables you can implement a move generation with allmost
no illegal moves with much less costs than a full move generation.
3. The legality of a position can be calculated at no cost.
4. We use attack tables for king security. As king security will produce high
positional values it would´nt be a candidate for lazy eval.
5. We use attack tables for mate in 1 detection at every ply
6. We use attack tables for a simple SEE (not yet implemented but an easy table
lookup).

On the other hand, attack table generation is really expensive, even if it is
done incrementally. Without any eval (just material) we are just as fast as
ruffian.

Greetings Volker



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