Editing Deep Blue (chess computer) (section)

== Deep Blue versus Kasparov ==
{{Main|Deep Blue versus Garry Kasparov}}
[[File:Kasparov Magath 1985 Hamburg-2.png|thumb|[[Garry Kasparov]] playing a [[simultaneous exhibition]] in 1985]]

Subsequent to its predecessor Deep Thought's 1989 loss to [[Garry Kasparov]], Deep Blue played Kasparov twice more. In the first game of the first match, which took place from 10 to 17 February 1996, Deep Blue became the first machine to win [[Deep Blue versus Kasparov, 1996, Game 1|a chess game against a reigning world champion]] under [[Rules of chess|regular time controls]]. However, Kasparov won three and drew two of the following five games, beating Deep Blue by 4–2 at the close of the match.<ref>{{cite book |last1=Stuart Russell and Peter Norvig |first1=Stuart Russell and Peter Norvig |title=Artificial Intelligence: A Modern Approach |date=2020 |publisher=Pearson |isbn=9780134610993 |page=3 |edition=4th}}</ref><ref>{{Harvnb| Newborn|1997|page=287}}</ref>

Deep Blue's hardware was subsequently upgraded,<ref name=":0" /><ref>{{Cite news |last1=McPhee |first1=Michele |last2=Baker |first2=K.C. |last3=Siemaszko |first3=Corky |date=10 May 2015 |title=IBM's Deep Blue beats chess champion Garry Kasparov in 1997 |language=en |work=[[Daily News (New York)|Daily News]] |location=New York |url=http://www.nydailynews.com/news/world/kasparov-deep-blues-losingchess-champ-rooke-article-1.762264 |access-date=3 August 2017 |archive-date=3 August 2017 |archive-url=https://web.archive.org/web/20170803171244/http://www.nydailynews.com/news/world/kasparov-deep-blues-losingchess-champ-rooke-article-1.762264 |url-status=live }}</ref>{{efn|Unofficially nicknamed "Deeper Blue".<ref>[http://www.research.ibm.com/deepblue/games/game2/html/c.2.shtml IBM Research Game 2] {{webarchive|url=https://web.archive.org/web/20071019031508/http://www.research.ibm.com/deepblue/games/game2/html/c.2.shtml |date=19 October 2007 }}, Deep Blue [[IBM]]</ref>}} doubling its speed before it faced Kasparov again in May 1997, when it won the six-game rematch 3½–2½. Deep Blue won the [[Deep Blue versus Kasparov, 1997, Game 6|deciding game]] after Kasparov failed to secure his position in the opening, thereby becoming the first computer system to defeat a reigning world champion in a match under standard chess tournament time controls.<ref>{{Cite magazine |last=Saletan |first=William |author-link=William Saletan |date=11 May 2007 |title=Chess Bump: The triumphant teamwork of humans and computers |url=http://www.slate.com/id/2166000/ |url-status=live |magazine=[[Slate (magazine)|Slate]] |archive-url=https://web.archive.org/web/20070513035007/http://www.slate.com/id/2166000/ |archive-date=13 May 2007}}</ref><ref name="Roberts" /> The version of Deep Blue that defeated Kasparov in 1997 typically searched to a depth of six to eight moves, and twenty or more moves in some situations.<ref>{{Harvnb|Campbell|1998|page=88}}</ref> [[David Levy (chess player)|David Levy]] and [[Monty Newborn]] estimate that each additional [[Ply (game theory)|ply]] (half-move) of forward insight increases the playing strength between 50 and 70 [[Elo rating system|Elo]] points.<ref>{{Harvnb|Levy|Newborn|1991|page=192}}</ref>

In the 44th move of the first game of their second match, unknown to Kasparov, a [[Software bug|bug]] in Deep Blue's code led it to enter an unintentional [[Control flow#Count-controlled loops|loop]], which it exited by taking a randomly selected valid move.<ref name="Plumer" /> Kasparov did not take this possibility into account, and misattributed the seemingly pointless move to "superior intelligence".<ref name="Roberts">{{Cite journal |last=Roberts |first=Jacob |year=2016 |title=Thinking Machines: The Search for Artificial Intelligence |url=https://www.sciencehistory.org/distillations/magazine/thinking-machines-the-search-for-artificial-intelligence |url-status=dead |journal=Distillations |volume=2 |issue=2 |pages=14–23 |archive-url=https://web.archive.org/web/20180819152455/https://www.sciencehistory.org/distillations/magazine/thinking-machines-the-search-for-artificial-intelligence |archive-date=19 August 2018 |access-date=22 March 2018}}</ref> Subsequently, Kasparov experienced a decline in performance in the following game,<ref name="Plumer">{{Cite web |last=Plumer |first=Brad |date=26 September 2012 |title=Nate Silver's 'The Signal and the Noise' |url=https://www.washingtonpost.com/news/wonk/wp/2012/09/26/nate-silvers-the-signal-and-the-noise/ |url-status=live |archive-url=https://web.archive.org/web/20121109100324/http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/09/26/nate-silvers-the-signal-and-the-noise/ |archive-date=9 November 2012 |access-date=18 August 2021 |newspaper=The Washington Post}}</ref> though he denies this was due to anxiety in the wake of Deep Blue's inscrutable move.<ref>{{Cite book |title=LC Catalog – Item Information (Full Record) |lccn=2017304768}}</ref>

After his loss, Kasparov said that he sometimes saw unusual creativity in the machine's moves, suggesting that during the second game, human chess players had intervened on behalf of the machine. IBM denied this, saying the only human intervention occurred between games.<ref>{{Cite web |last=Silver |first=Albert |date=19 February 2015 |title=Deep Blue's cheating move |url=https://en.chessbase.com/post/deep-blue-s-cheating-move |access-date=3 June 2020 |website=Chess Base |publisher=Chess News |archive-date=29 July 2020 |archive-url=https://web.archive.org/web/20200729034238/https://en.chessbase.com/post/deep-blue-s-cheating-move |url-status=live }}</ref><ref>{{Harvnb|Hsu|2004|page=x}}</ref> Kasparov demanded a rematch, but IBM had dismantled Deep Blue after its victory and refused the rematch.<ref>{{Harvnb|Warwick|2004|page=95}}</ref> The rules allowed the developers to modify the program between games, an opportunity they said they used to shore up weaknesses in the computer's play that were revealed during the course of the match. Kasparov requested printouts of the machine's log files, but IBM refused, although the company later published the logs on the Internet.<ref>{{Cite web |title=Deep Blue – Replay the Games |url=http://www.research.ibm.com/deepblue/watch/html/c.shtml |url-status=dead |archive-url=https://web.archive.org/web/20080701232743/http://www.research.ibm.com/deepblue/watch/html/c.shtml |archive-date=1 July 2008 |access-date=10 June 2020 |website=IBM Research}}</ref>

The 1997 tournament awarded a $700,000 first prize to the Deep Blue team and a $400,000 second prize to Kasparov. [[Carnegie Mellon University]] awarded an additional $100,000 to the Deep Blue team, a prize created by computer science professor [[Edward Fredkin]] in 1980 for the first computer program to beat a reigning world chess champion.<ref>{{cite news |url=https://www.nbcnews.com/id/wbna5191763 |title=How prizes pushed progress |first=Alan |last=Boyle |work=NBC News |date=16 June 2004 |access-date=23 January 2024}}</ref>