Timothy Hart

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Timothy Hart [1] Timothy P. Hart, (September 18, 1939 - January 20, 2014 [2])

was an American computer scientist, in the 60s affiliated with Massachusetts Institute of Technology, and in 1970 co-founder of Evans, Griffiths and Hart, Inc, EGH. As MIT graduate Timothy Hart was involved in the initial development of LISP within the group of John McCarthy. Along with Daniel Edwards, Timothy Hart wrote a memo on Alpha-Beta in December 1961, revised version in 1963 [3]. It also contains a Theorem by Michael Levin, the well known formula of the number of leaf nodes that need to be examined in Alpha-Beta.

Alpha-Beta

Quote by John McCarthy from Human-Level AI is harder than it seemed in 1955 on the Dartmouth workshop:

Chess programs catch some of the human chess playing abilities but rely on the limited [effective branching](Branching_Factor "Branching Factor") of the chess move [tree](Search_Tree "Search Tree"). The ideas that work for chess are inadequate for [go](Go "Go"). [Alpha-beta pruning](Alpha-Beta "Alpha-Beta") characterizes human play, but it wasn't noticed by [early chess programmers](Category:Pioneer "Category:Pioneer") - [Turing](Alan_Turing "Alan Turing"), [Shannon](Claude_Shannon "Claude Shannon"), [Pasta](John_Pasta "John Pasta") and [Ulam](Stanislaw_Ulam "Stanislaw Ulam"), and [Bernstein](Alex_Bernstein "Alex Bernstein"). We humans are not very good at identifying the heuristics we ourselves use. Approximations to alpha-beta used by [Samuel](Arthur_Samuel "Arthur Samuel"), [Newell](Allen_Newell "Allen Newell") and [Simon](Herbert_Simon "Herbert Simon"), McCarthy. Proved equivalent to [minimax](Minimax "Minimax") by Hart and [Levin](Michael_Levin "Michael Levin"), independently by [Brudno](Alexander_Brudno "Alexander Brudno"). [Knuth](Donald_Knuth "Donald Knuth") gives details.

LISP

Quote by John McCarthy in History of Lisp [4]:

Many people participated in the initial development of [LISP](index.php?title=LISP&action=edit&redlink=1 "LISP (page does not exist)"), and I haven't been able to remember all their contributions and must settle, at this writing, for a list of names. I can remember [Paul W. Abrahams](Paul_W._Abrahams "Paul W. Abrahams"), [Robert Brayton](Mathematician#RKBrayton "Mathematician"), [Daniel Edwards](Daniel_Edwards "Daniel Edwards"), [Patrick Fischer](Mathematician#PCFischer "Mathematician"), [Phyllis Fox](Mathematician#PFox "Mathematician"), [Saul Goldberg](http://www.ee.calpoly.edu/faculty/sgoldber/), Timothy Hart, [Louis Hodes](Mathematician#LHodes "Mathematician"), [Michael Levin](Michael_Levin "Michael Levin"), [David Luckham](Mathematician#DLuckham "Mathematician"), Klim Maling, [Marvin Minsky](Marvin_Minsky "Marvin Minsky"), [David Park](Mathematician#DPark "Mathematician"), [Nathaniel Rochester](Nathaniel_Rochester "Nathaniel Rochester") of [IBM](index.php?title=IBM&action=edit&redlink=1 "IBM (page does not exist)"), and [Steve Russell](https://en.wikipedia.org/wiki/Steve_Russell_(computer_scientist)).