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PostModernist is a chess program written by Andrew
Williams. It is not yet publicly available, but it plays most evenings
and all weekend at the
Internet Chess
Club. PostModernist doesn't have a user-interface of its own; instead
it relies on XBoard,
a generic interface created by Tim Mann. It is through XBoard that PostModernist
is able to play online at the various Internet Chess Servers.
Search Control
PostModernist is slightly unusual in that it uses MTD(f) (Memory Test
Driver with first guess, f) to drive its search. This is in contrast
to the more common Principal Variation Search. Aske Plaat, who investigated
the characteristics of MTD in his PhD thesis, claims that it is simpler
than other methods and that there is no reason not to use MTD. While it
is true that MTD is simple to understand, there are significant practical
difficulties in its use - specifically, the derivation of a Principal Variation
to guide the search. Despite its reputed superior speed, MTD has not really
caught on. Aske Plaat has provided a
simple online description of the method. This is where I started when
I converted PostModernist to MTD.
Hash Table
All modern computer chess programs make extensive use of a hash table to
"remember" details about the search. PostModernist is no exception; indeed
in MTD implementations, the hash table takes on increased significance,
because of the repeated probes of the search space. PostModernist's hash
table entries contain an upper and a lower bound. As the search progresses,
the gap between the bounds is narrowed until they meet, with the meeting
point being the exact score for the position.
Opening Book
PostModernist has a three-part opening book. Its main ("big") book is built
from the enormous collection of PGN games which can be found at Dann
Corbit's FTP site. This book is approximately 430MB in size. In addition,
it is possible to define preferred openings for PostModernist when playing
White or Black. These go in the two "coloured" books. Insofar as PostModernist
could be said to have a tournament book, it is represented in these white
and black books. The big book then becomes a fall-back for when the tournament
lines come to an end. Normally when running on the Internet Chess Club,
PostModernist just uses the big book. For the first ICC Computer Chess
Tournament (see below), I devised very simple coloured books to help the
program to avoid doing anything too stupid early in the game.
The First ICC Computer Chess Tournament
PostModernist took part in the First Internet Chess Club Computer
Chess Tournament. It scored 5.0/8 and finished 5th out of 22 entrants -
an excellent result! You can see a detailed breakdown, and play through the games
here.
Download (some of) PostModernist's Games
Since August 1999, PostModernist has used a PIII-450 to play at the ICC. It has played over 20000
games in that time. I've collected together all the standard time control games up to 10th July 2000.
Standard on ICC means 15 minutes or longer.
Click here to download all PostModernist's games at "standard" time controls.
(Approx 750k)
New! Studies from PostModernist's games
Click here to look at some study-like positions from PostModernist's games on ICC.
To see the solution, move the mouse over the diagram.
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