Encyclopedia of Computer Science and Technology

Turing, Alan Mathison 481Online attacks on reputation (defamation) are also agrowing problem for both businesses and individuals. Evenif the perpetrator is legally prosecuted or otherwise forcedto stop, removing the defamatory material (and links to it)can be difficult, since the material may have been extensivelycached, archived, or otherwise copied. Thus consultantsin “reputation management” have begun to offer theirservices to the victims of undeserved negative reputations.(This includes optimizing for search engines so that negativematerial will be pushed to the bottom of the results.)Further ReadingDellarocas, Chrysanthos. “Reputation Mechanisms” [overviewand resources]. University of Maryland, R. H. Smith School ofBusiness. Available online. URL: http://www.washingtonpost.com/wp-dyn/content/article/2007/07/01/AR2007070101355.html? hpid=artslot. Accessed November 29, 2007.Kinzie, Susan, and Ellen Nakashima. “Calling In Pros to RefineYour Google Image.” Washington Post.com, July 2, 2007.Available online. URL: http://www.washingtonpost.com/wp-dyn/content/article/2007/07/01/AR2007070101355.html?hpid=artslot. Accessed November 29, 2007.Masum, Hassan, and Yi-Cheng Zhang. “Manifesto for the ReputationSociety.” First Monday, vol. 9 (July 2004). Availableonline. URL: http://www.firstmonday.org/issues/issue9_7/masum/index.html. Accessed November 29, 2007.Solove, Daniel J. The Future of Reputation: Gossip, Rumor, and Privacyon the Internet. New Haven, Conn.: Yale University Press,2007.Trust Metrics Evaluation Project. Available online. URL: http://www.trustlet.org/wiki/Trust_Metrics_Evaluation_project.Accessed November 29, 2007.Turing, Alan Mathison(1912–1954)BritishMathematician, Computer ScientistAlan Turing’s broad range of thought pioneered manybranches of computer science, ranging from the fundamentaltheory of computability to the question of what mightconstitute true artificial intelligence.Turing was born in London on June 23, 1912. His fatherworked in the Indian (colonial) Civil Service, while hismother came from a family that had produced a number ofdistinguished scientists. As a youth Turing showed greatinterest and aptitude in both physical science and mathematics.When he entered King’s College, Cambridge, in1931, his first great interest was in probability, where hewrote a well-regarded thesis on the Central Limit Theorem.Turing’s interest then turned to the question of whatproblems could be solved through computation (see computabilityand complexity). Instead of pursuing conventionalmathematical strategies, he re-imagined the problemby creating the Turing Machine, an abstract “computer”that performs only two kinds of operations: writing ornot writing a symbol on its imaginary tape, and possiblymoving one space on the tape to the left or right. Turingshowed that from this simple set of states (see finitestate machine) any possible type of calculation could beconstructed. His 1936 paper “On Computable Numbers”together with another researcher’s different approach (seeChurch, Alonzo) defined the theory of computability.Turing then came to America, studied at Princeton University,and received his Ph.D. in 1938.Turing did not remain in the abstract realm, however,but began to think about how actual machines could performsequences of logical operations. When World War IIerupted, Turing returned to Britain and went into servicewith the government’s Bletchley Park code-breaking facility.He was able to combine his previous work on probabilityand his new insights into computing devices to help analyzecryptosystems such as the German Enigma cipher machineand to design specialized code-breaking machines.As the war drew to an end, Turing’s imagination broughttogether what he had seen of the possibilities of automaticcomputation, and particularly the faster machines thatwould be made possible by harnessing electronics ratherthan electromechanical relays. In 1946, he received a Britishgovernment grant to build the ACE (Automatic ComputingEngine). This machine’s design incorporated advanced programmingconcepts such as the storing of all instructionsin the form of programs in memory without the mechanicalsetup steps required for machines such as the ENIAC.Another important idea of Turing was that programs couldmodify themselves by treating their own instructions justlike other data in memory. However, the engineering of theadvanced memory system led to delays, and Turing left theproject in 1948 (it would be completed in 1950). Turing alsocontinued his interest in pure mathematics and developed anew interest in a completely different field, biochemistry.Turing’s last and perhaps greatest impact would come inthe new field of artificial intelligence. Working at the Universityof Manchester, Turing devised a concept that becameknown as the Turing Test. In its best-known variation, thetest involves a human being communicating via a Teletypewith an unknown party that might be either another personor a computer. If a computer at the other end is sufficientlyable to respond in a humanlike way, it may fool the humaninto thinking it is another person. This achievement couldin turn be considered strong evidence that the computer istruly intelligent. Since Turing’s 1950 article computer programssuch as ELIZA and Web “chatterbots” have been ableto temporarily fool people they encounter, but no computerprogram has yet been able to pass the Turing Test whensubjected to extensive probing questions by a knowledgeableperson.Alan Turing had a secret that was very dangerous in thattime and place: He was gay. In 1952, the socially awkwardTuring stumbled into a set of circumstances that led to hisbeing arrested for homosexual activity, which was illegaland heavily punished at the time. The effect of his trial andforced medical “treatment” suggested that his death fromcyanide poisoning on June 7, 1954, was probably a suicide.Alan Turing’s many contributions to computer sciencewere honored by his being elected a Fellow of the BritishRoyal Society in 1951 and by the creation of the prestigiousTuring Award by the Association for Computing Machinery,given every year since 1966 for outstanding contributionsto computer science.