History
The history of WZebra is very much the history of Zebra,
the Othello engine which WZebra uses when playing.
Here are some important events:
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June 3, 1997
-
Gunnar Andersson starts working on an Othello program which
he decides to call Zebra.
After three weeks, it reaches a rating of 1500 on the Internet Othello
Server (IOS), corresponding to an amateur human player.
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August 1997
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The crude evaluation function and search algorithms work properly.
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September 1997
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All major program components - opening book, hash table,
endgame solver - implemented and debugged.
The IOS rating is now 1900, stronger than most players in the
World Championships.
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January 1998
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A new pattern-based evaluation function is tuned and debugged.
The IOS rating leaps to 2300, higher than all humans.
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March 1998
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Midgame and endgame search are vastly improved through the use of
the Multi Prob-Cut algorithm.
An improved opening book algorithm is tested.
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May 1998
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Zebra beats Hannibal, the strongest Othello program, for the first time.
The IOS rating is now above 2500, making it one of the five strongest
programs in the world.
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May 1998
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Lars Ivansson starts working on a graphical user's interface for Zebra.
He decides to call the program WZebra.
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June 1998
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The first version of WZebra is released as freeware.
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August 1998
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WZebra 1.41 is released.
This is the first version without serious bugs.
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October 1998
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Zebra finishes 3rd in the prestigious Princeton II tournament
for computer programs (winner was Hannibal and runner-up was Logistello).
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Spring 1999
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Zebra's search algorithms undergo a revision that gives great speedups.
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July 1999
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More corner knowledge is added to the evaluation function and some bugs
in the evaluation function are removed.
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October 1999
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The IOS version of Zebra which only plays rand games, Reindeer,
reaches a rating of 2932.
At that point, Reindeer had the highest rating of all active players on IOS.
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November 1999
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WZebra 2.0 is released.
Compared to earlier versions it plays stronger and has many new functions.
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January 2000
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WZebra 2.1, with support for the Thor database, is released.
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October 2000
-
WZebra 2.2 is released.
Compared to earlier versions, it provides a faster endgame and
a stronger and larger opening book.
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November 2001
-
WZebra 3.0 is released.
It contains new features, new graphics design, and a faster Othello engine.
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January 2002
-
WZebra 3.1 is released.
It features improved graphics and new features.
May 2002
WZebra 3.2 is released. It has more features and less bugs than previous
versions, and also an evaluation function which understands rare board
positions better.
August 2002
WZebra and LZebra 3.3 are released.
The latter is a Linux port of WZebra, both contain the same set of features.
November 2002
WZebra 4.0 is released.
It contains many new features and bug fixes.
Furthermore, its midgame searches are deeper.
January 2003
WZebra 4.1 is released.
It has a faster endgame solver than previous versions.
April 2003
WZebra 4.2 is released.
It features improved fully configurable board graphics, including a 3D mode.