Changes

My chess program (before then there was a knight tour, connect4, [[Othello|simple othello]] and others to learn [[Recursion|recursion]] and [[Search|search]] etc) started as my expanded interpretation of [[TSCP]], helped by articles on the internet (particularly [[Tony Marsland|Marsland's]] excellent summary of the anatomy of a chess program) <ref> [[Tony Marsland]] ('''1995'''). ''[http://ilk.uvt.nl/icga/games/chess/anatomy.php The Anatomy of Chess Programs]''. [http://www.computerhistory.org/chess/full_record.php?iid=doc-431614f6cd6ed 8th World Computer Chess Championship] pp. 4-6, [http://archive.computerhistory.org/projects/chess/related_materials/text/3-1%20and%203-2%20and%203-3%20and%204-3.1995_WCCC/1995%20WCCC.062303014.sm.pdf pdf] from [[The Computer History Museum]], Courtesy of [[Monroe Newborn]]</ref> and of course by members of [[CCC]] and particulalry [[Robert Hyatt|Bob Hyatt]]. Now its origins are unrecognisable, although [[Mailbox|mailbox]] is still used to precompute [[Table-driven Move Generation|move tables]] - simply because I had already written that code. The last major rewrite, two years or so ago introduced [[Bitboards|bitboards]] (because they looked interesting and Bob is always talking about them) to use mainly in [[Evaluation|evaluation]]. [[Move Generation|Move generation]], [[King Pattern#KingAttacks|king attacks]], is a [[Square Attacked By|square attacked]], [[Static Exchange Evaluation|SEE]] etc is a mixture of bitboards for the easy cases (knights, pawns, king) and offset precomputed arrays for the sliders. Like [[Dan Newman]] (I think), I also use bitboards to screen for _potential_ slider attacks etc to reduce work, but do not precompute the rank, file or diagonal states to give an index to a bitboard of the first square attacked. Full and [[Rotated Bitboards|rotated bitboards]] implementation next time. Maybe after an IQ transplant, or to get cheap [[Mobility|mobility]]. Move generation is not a massive drain in my program, so bitboards are more valuable for their other benefits. Search is pretty standard [[Crafty]] type approach. Tried and discarded [[DarkThought|Dark Thought]] type [[Pruning|pruning]]. But will try again after listening to [[Bruce Moreland|Bruce]] on [[CCT3]]. [[Extensions]] as recommended by Bob and limited as recommend by Bruce, although I still have [[Recapture Extensions|recapture extension]] because it seems to help me and do a bit extra for [[Passed Pawn Extensions|passed pawns]]. Tested other and other variations of extensions without much impact. All sorts of daft ideas. [[Transposition Table|Trans/ref hash]] and [[Pawn Hash Table|hashing of basic pawn structure]] elements. [[Nalimov Tablebases|Nalimov EGTBs]] (3 years to generate all 5 man on and off, on a variety of machines. Thanks [[Eugene Nalimov|Eugene]]), primitive [[Book Learning|book learning]] and [[Learning|positional learning]]. The evaluation has become increasingly sophisticated (voluminous anyway) with time. Playing on the [[Chess Server|chess servers]], even for a brief time, has certainly caused me to add stuff.