Computer Chess Club Archives




Subject: queen mobility

Author: Sebastian Leibnitz

Date: 12:37:24 01/18/06

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On January 18, 2006 at 15:05:36, Dann Corbit wrote:

>On January 18, 2006 at 14:39:40, Fernando Villegas wrote:
>>Some days ago I talked of knowledege to know which knowledge is irrelevant as a
>>probable feature of Rybka. And almost nobody answered or commented my post.
>>Surely it is an advantage to be a chess programmer in a site like this.
>Probably the only one who can answer correctly is the author.
>But you can look at some interesting generalizations.
>I have found that some evaluation terms add nothing either to the EPD solution
>count or the contest point gathering effectiveness of an engine.
>An example is queen mobility.  I don't know of any logical reason why its
>computation should not help, but it doesn't.

My brother (ELO 2150) is always a rich source of info for me.

Once we were discussing mobility eval (read: I was pestering him about his
ideas) and he remarked that he cannot conceive how queen mobility should be

His argument:

- static eval as a snapshot is virtually unable to tell if the queen has a lot
of options or not as a queen can usually "worm her way out of almost any
spot/hole", can easily swith between black/light squares as not to be blocked by
pawn chains, etc.
- he (admits that he) is envious of our silicon friends because they can deal so
well with queens due to thein search and humans have nothing against it because
(I quote) "queens are the LEAST positional chess piece existing, EVEN BEHIND the
empty square"(on those he has a lot of interesting positional things to say!)

His advice (regarding queen mobility) was to:

1.) only check wheather the queen was somehow blocked (totally)
2.) he also advised me to extend search if that was the case

  I have not yet tried 2), but I'll stick with having to queen mobility eval

3.) only to really deal with queens (as of now, more important things to do)
with regard to
  a) enemy king safety
  b) support for rooks/bishops on their open files/diagonals resp.

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