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'''Atlas''',<br/>
an early chess program written in 1967 by [[Alex Bell]] at [[Atlas Computer Laboratory]], [https://en.wikipedia.org/wiki/Chilton,_Oxfordshire Chilton]. It was basically a resurrected, cleaned up [[Algol]] version of Bell's and [[Nils Barricelli|Barricelli's]] old program from the early 60s to test evolutionary theories, which had an [[Evaluation functionFunction|evaluation function]] based purely on [[Mobility|mobility]] - at that time the first fully legal chess program to run in England <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, and likely also the base of Barricelli's [[WCCC 1974]] entry [[Freedom]].
Atlas, running on an [https://en.wikipedia.org/wiki/International_Computers_Limited ICL] [https://en.wikipedia.org/wiki/Atlas_%28computer%29 Atlas] computer <ref>[http://www.chilton-computing.org.uk/acl/literature/acl/p004.htm Atlas Computer Laboratory], hosted by [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, looked three [[Ply|plies]] ahead with [[Alpha-Beta|alpha-beta]], and would accept almost any [[Captures|captures]] in that [[Depth|depth]] with weighting on swaps of the more powerful pieces, i.e. it would always swap a queen for a queen. If no captures were present it prepared to [[Castling|castle]] or [[Minimax|mini-maximised]] its mobility. A slight modification prevented it from moving its queen in the first 5 moves <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>. Atlas played a few sparring games against [[Lancaster]] <ref>[[John J. Scott]] ('''1969'''). ''Lancaster vs. Mac Hack''. [[ACM#SIG|ACM SIGART Bulletin]], Vol. 16</ref>, [[John J. Scott|John Scott's]] program, then dubbed "Scott" <ref>[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p005.htm#index22 Chess programs: Scott] from [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]</ref>, and largely suffered from [[Horizon Effect|horizon effect]].
