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Subject: Re: Improving an engine

Author: Gian-Carlo Pascutto

Date: 02:28:46 09/24/01

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On September 24, 2001 at 05:13:13, Adrian Smith wrote:

>What methods and ways can you turn a simple searching chess program into a more
>competitive program?

First thing is to get a decent search. There is quite a bit
written on this, and you can look at the public chess engines
for good ideas. I think getting a decent search is important
because it will avoid you getting tactically crushed every
time.

You want to look into PVS, aspiration windows (MTD if you feel
brave), killers, history heuristic, SEE (or MVV/LVA for starters),
check extensions, recapture extensions, singular reply extensions,
qsearch futility pruning and lots of other things.

Implement what you _understand_ first. You don't need everything
if you are getting started. If you have quesions, ask them here.
There's lots of people that like to help out beginners.

You can test & tune this on WAC, ECM/WAC2. Be sure to also run
some quiet positions and check if you're not blowing up the tree
or ruining your branching factor on deeper searches.

Next thing is the evaluation. A simple piece-square + passed
pawns (like Gerbil) is good to get something working. The problem
with evaluation is that there are all kinds of thing you would
want your program to know and it's harder to know what is most
important.

For this reason, ICC/FICS are a great testbed. You can let
your engine play vs other engines and human players and see
where things go wrong. If it are pure tactical busts (should
be rare with decent search) you are SOL. If your program
missed something, like it didn't understand it's king was in
trouble, or it misplayed an endgame, you can take a look at
fixing it.

I would think that for a simple engine passed pawns and
kingsafety are probably the most important. More advanced
concepts can come later on.

--
GCP



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