Editing Deep Blue (chess computer) (section)

=== Software ===
Deep Blue ran under the [[AIX operating system]], and its chess playing program was written in [[C (programming language)|C]]. 
Its [[evaluation function]] was initially written in a generalized form, with many to-be-determined parameters (e.g., how important is a safe king position compared to a space advantage in the center, etc.). Values for these parameters were determined by analyzing thousands of master games. The evaluation function was then split into 8,000 parts, many of them designed for special positions. The opening book encapsulated more than 4,000 positions and 700,000 [[Grandmaster (chess)|grandmaster]] games, while the endgame database contained many six-piece endgames and all five and fewer piece endgames. An additional database named the "extended book" summarizes entire games played by Grandmasters. The system combines its searching ability of 200 million chess positions per second with summary information in the extended book to select opening moves.<ref>{{Harvnb|Campbell|1999|page=66}}</ref>

Before the second match, the program's rules were fine-tuned by grandmaster [[Joel Benjamin]]. The opening library was provided by grandmasters [[Miguel Illescas]], [[John Fedorowicz]], and [[Nick de Firmian]].<ref>{{Cite news |last=Weber |first=Bruce |date=18 May 1997 |title=What Deep Blue Learned in Chess School |language=en-US |work=The New York Times |url=https://www.nytimes.com/1997/05/18/nyregion/what-deep-blue-learned-in-chess-school.html |access-date=4 July 2017 |issn=0362-4331 |archive-date=17 May 2017 |archive-url=https://web.archive.org/web/20170517052341/http://www.nytimes.com/1997/05/18/nyregion/what-deep-blue-learned-in-chess-school.html |url-status=live }}</ref> When Kasparov requested that he be allowed to study other games that Deep Blue had played so as to better understand his opponent, IBM refused, leading Kasparov to study many popular PC chess games to familiarize himself with computer gameplay.<ref>{{Cite web |last=Weber |first=Bruce |date=5 May 1997 |title=Computer Defeats Kasparov, Stunning the Chess Experts |url=https://www.nytimes.com/1997/05/05/nyregion/computer-defeats-kasparov-stunning-the-chess-experts.html |website=[[The New York Times]] |access-date=18 May 2020 |archive-date=24 April 2020 |archive-url=https://web.archive.org/web/20200424155122/https://www.nytimes.com/1997/05/05/nyregion/computer-defeats-kasparov-stunning-the-chess-experts.html |url-status=live }}</ref>