Editing KnightCap (section)

{{Short description|Open-source computer cheese engine}}
{{Refimprove|date=January 2025}}
{{Infobox software
| title = KnightCap
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| author = [[Andrew Tridgell]]
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| genre = [[Chess engine]]
| license = [[GNU General Public License]]
| website = {{URL|https://www.samba.org/KnightCap/}}
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{{Chess programming series}}

'''KnightCap''' is an open source [[computer]] [[chess engine]]. Its primary author is [[Andrew Tridgell]] and it was created circa 1996. Major contributions have also been made by [[Jon Baxter]] and probably minor contributions by a few others. KnightCap is [[free software]] released under the [[GNU General Public License]] (GPL).

In most ways, KnightCap is a fairly typical modern program. It uses [[bitboard]] data structures that are slightly different from those that were well known in 1996, but obvious enough and probably well known now. There is backward pruning using [[MTD(f)]] (a method approximately equivalent to [[Alpha-beta pruning]] but slightly more efficient in some settings). There is [[Null-move heuristic]]. There is a fairly complex end-node evaluation process that considers similar features to other programs.

In addition, KnightCap has support for multi-processor computers, in particular the now obsolete [[Fujitsu_Siemens_Computers#Products|Fujitsu CAP computer]]
research machines.

The most original feature of KnightCap, introduced in the late 1990s, was an experiment in [[temporal difference learning]] as applied to chess. This technique allowed KnightCap to automatically tune the weights applied to the various features in its [[evaluation function]] based on the games it played.

For a while in the 1990s, KnightCap was quite active on [[chess servers]] on the Internet, but it is now semi-retired and rarely seen. Its strength is below that of the strongest programs, but still quite good.{{Fact|date=February 2007}}