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{{short description|American computer scientist; Planner programming languagedesigner (1944-2022)}}
'''Carl E. Hewitt''' is Associate ] in the ] and ] department at the ] (MIT).<ref>, MIT, accessed November 12, 2007.</ref>
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{{Pp-move}}
⚫ Hewitt is known for his design of ],<ref name=hewitt69>Carl Hewitt. IJCAI. 1969.</ref> which was the first ] based on procedural plans that were invoked using pattern-directed invocation from assertions and goals, and was influential in the development of both ] and ]. He is also known for his work on the ] of ],<ref>{{cite book|last=Filman|first=Robert|coauthors=Daniel Friedman|title=Coordinated Computing - Tools and Techniques for Distributed Software|year=1984|publisher=McGraw-Hill|isbn=0-07-022439-0|url=http://ic.arc.nasa.gov/people/filman/text/dpl/dpl.html|chapter=Actors|quote=Carl Hewitt and his colleagues at M.I.T. are developing the Actor model.|page= 145}}</ref> which influenced the development of the ] programming language<ref>{{cite journal|last=Krishnamurthi|first=Shriram|title= An Introduction to Scheme|journal=Crossroads|volume =1|issue=2|month=December | year=1994|url=http://www.acm.org/crossroads/xrds1-2/scheme.html}}</ref> and the ],<ref>{{cite journal|last=Milner|first=Robin|authorlink=Robin Milner |title=ACM Turing Award Lecture: The Elements of Interaction|url=http://fresh.homeunix.net/~luke/misc/papers/milner-interaction.pdf|format=PDF|journal=Communications of the ACM|volume=36|issue = 1|month=January | year=1993}}</ref> and served as an inspiration for several other programming languages.<ref name="miller2006">{{cite paper| author = Mark S. Miller | title = Robust Composition - Towards a Unified Approach to Access Control and Concurrency Control | version = PhD dissertation| url = http://www.cypherpunks.to/erights/talks/thesis/submitted/markm-thesis.pdf | format=PDF
{{Infobox scientist
| publisher = Johns Hopkins University | year = 2006 | accessdate = 2007-05-26}}</ref> His publications also include contributions in the areas of ],<ref name=Hewitt1986>{{cite paper|author=Carl Hewitt|title=Offices Are Open Systems|publisher=ACM Trans. Inf. Syst. 4(3): 271-287|year=1986}}</ref> ]s,<ref>{{cite book|author=Jacques Ferber|title=Multi-Agent Systems: An Introduction to Distributed Artificial Intelligence|publisher=Addison-Wesley|year=1999}}</ref>
| name = Carl Hewitt
],<ref name=hewitt69/><ref> {{citation |first=Carl|last=Hewitt|url=http://hewitt-seminars.blogspot.com/2008/05/development-of-logic-programming-what.html |chapter=Development of Logic Programming: What went wrong, What was done about it, and What it might mean for the future|publisher=AAAI Press|year=2008|title=What Went Wrong and Why: Lessons from AI Research and Applications|editor-first=Mehmet|editor-last=Goker|editor2-first=Daniel|editor2-last=Shapiro}}</ref> concurrent ]s,<ref name="Hewitt2008b">{{cite web | author=Hewitt, Carl| title=Common sense for concurrency and strong paraconsistency using unstratified inference and reflection | format= |url=http://arxiv.org/abs/0812.4852v2}} ArXiv. December 30, 2008.</ref> ],<ref name=Hewitt2008>{{citation |first=Carl|last=Hewitt|url=http://hewitt-seminars.blogspot.com/2008/03/large-scale-organizational-computing.html |chapter = Large-scale Organizational Computing requires Unstratified Reflection and Strong Paraconsistency|publisher=Springer-Verlag|year=2008|title=Coordination, Organizations, Institutions, and Norms in Agent Systems III|editor-first=Jaime|editor-last=Sichman|editor2-first=Pablo|editor2-last=Noriega|editor3-first=Julian|editor3-last=Padget|editor4-first=Sascha|editor4-last=Ossowski}}</ref> ].<ref>{{cite journal|author=Carl Hewitt|title=ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing|journal=IEEE Internet Computing|volume=12|issue=5|date=September/October 2008}} </ref><ref>{{cite web|author = Carl Hewitt |title= A historical perspective on developing foundations for privacy-friendly client cloud computing|url = http://knol.google.com/k/carl-hewitt/a-historical-perspective-on-developing/pcxtp4rx7g1t/7#|accessdate = 2008-10-19}}</ref> Hewitt's ] is 3 (by two different co-authors).
| birth_date = {{Birth-date|1944}}<ref>{{Cite web|url=https://www.legacy.com/us/obituaries/santacruzsentinel/name/carl-hewitt-obituary?id=38594220|title=Carl Hewitt Obituary (1944 - 2022) - Aptos, CA - Santa Cruz Sentinel|website=Legacy.com}}</ref>
| birth_place =
| death_date = {{death date and given age|2022|12|7|77}}
| death_place = ]
| fields = ]<br />]<br />]<br />]s<br />]
| workplaces = ]<br />]<br />]
| patrons =
| alma_mater = ]
| thesis_title =
| thesis_url =
| doctoral_advisor = ]
| academic_advisors = ]<br />]
| doctoral_students = ]<br />]<br />]<br />]<br />]
| known_for = ]<br />Inconsistency robustness<br />] (])<br />Comparative schematology
| website =
| image = File:Hewitt-Carl-2008.jpg
| caption = Carl Hewitt in 2008
⚫ }}
⚫ '''Carl Eddie Hewitt''' ({{IPAc-en|ˈ|h|j|uː|ɪ|t}}; 1944 – 7 December 2022)<ref name="hewittstanf"> Stanford. 2022.</ref> was an American computer scientist who designed the ] for ]<ref name="hewitt69">Carl Hewitt. IJCAI. 1969.</ref> and the ] of ],<ref>{{cite book|last=Filman|first=Robert|author2=Daniel Friedman|title=Coordinated Computing - Tools and Techniques for Distributed Software|year=1984|publisher=McGraw-Hill|isbn=978-0-07-022439-1|chapter-url=http://ic.arc.nasa.gov/people/filman/text/dpl/dpl.html|chapter=Actors|quote=Carl Hewitt and his colleagues at M.I.T. are developing the Actor model.|page=|access-date=2007-04-22|url=https://archive.org/details/coordinatedcompu0000film/page/145}}</ref> which have been influential in the development of ], ] and ]. Planner was the first ] based on procedural plans invoked using pattern-directed invocation from assertions and goals. The actor model influenced the development of the ] programming language,<ref>{{cite journal|last=Krishnamurthi|first=Shriram|title=An Introduction to Scheme|journal=Crossroads|volume=1|issue=2|date=December 1994|url=http://www.acm.org/crossroads/xrds1-2/scheme.html|doi=10.1145/197149.197166|pages=19–27|s2cid=9782289|access-date=2007-04-22|archive-url=https://web.archive.org/web/20070425010522/http://www.acm.org/crossroads/xrds1-2/scheme.html|archive-date=2007-04-25|url-status=dead}}</ref> the ],<ref>{{cite journal|last=Milner|first=Robin|author-link=Robin Milner|title=ACM Turing Award Lecture: The Elements of Interaction|journal=Communications of the ACM|volume=36|issue=1|date=January 1993|doi=10.1145/151233.151240|pages=78–89|s2cid=14586773|doi-access=free}}</ref> and served as an inspiration for several other programming languages.<ref name="miller2006">{{cite thesis |last=Miller |first=Mark S. |date=2006 |title=Robust Composition - Towards a Unified Approach to Access Control and Concurrency Control |url=http://www.cypherpunks.to/erights/talks/thesis/submitted/markm-thesis.pdf |type=PhD |publisher=Johns Hopkins University |access-date=2007-05-26| archive-url = https://web.archive.org/web/20070810033528/http://www.cypherpunks.to/erights/talks/thesis/submitted/markm-thesis.pdf | archive-date = 2007-08-10 | url-status = dead}}</ref>


==Education and career== ==Education and career==
Hewitt obtained his ] in mathematics at MIT in 1971, under the supervision of ], ], and Mike Paterson. Hewitt started his employment at MIT in 1971.<ref>{{cite web|author = MIT News Office |title = Quarter Century Club inducts 73 new members |url = http://web.mit.edu/newsoffice/1996/qcc-0410.html| date = April 10, 1996| accessdate = 2007-06-19}}</ref> He retired from the faculty of the MIT Department of Electrical Engineering and Computer Science during the 1999-2000 school year.<ref>{{cite web|author=John V. Guttag|title= MIT Reports to the President 1999–2000 - Department of Electrical Engineering and Computer Science| url=http://web.mit.edu/annualreports/pres00/11.05.html|year = 2000 | accessdate = 2007-06-19}}</ref> Among the doctoral students that Hewitt supervised during his time at MIT are Professor Gul Agha, Dr. Russell Atkinson, Dr. ], Dr. Gerald Barber, Dr. Peter Bishop, Dr. Gene Ciccarelli, Professor William Clinger, Dr. Peter de Jong, Dr. Michael Freiling, Dr. Irene Greif, Dr. Kenneth Kahn, Dr. William Kornfeld and Professor ].<ref>{{cite web|author = Carl Hewitt |title= Academic Biography of Carl Hewitt|url = http://biography.carlhewitt.info|year= 2007|accessdate = 2007-11-22}}</ref> Hewitt obtained his ] in mathematics at MIT in 1971, under the supervision of ], ], and ]. He began his employment at MIT that year,<ref>{{cite web|author = MIT News Office |title = Quarter Century Club inducts 73 new members |url = http://web.mit.edu/newsoffice/1996/qcc-0410.html| date = April 10, 1996| access-date = 2007-06-19}}</ref> and retired from the faculty of the MIT ] during the 1999–2000 school year.<ref>{{cite web|author=John V. Guttag|title= MIT Reports to the President 1999–2000 – Department of Electrical Engineering and Computer Science| url=http://web.mit.edu/annualreports/pres00/11.05.html|year = 2000 | access-date = 2007-06-19}}</ref> He became emeritus in the department in 2000.<ref>{{cite web|title=Stanford EE Computer Systems Colloquium|url=http://www.stanford.edu/class/ee380/Abstracts/081022.html|publisher=Stanford University|access-date=30 July 2011}}</ref> Among the doctoral students that Hewitt supervised during his time at MIT are ], ], ], ], and ].<ref>{{cite web|author= Carl Hewitt|title= Academic Biography of Carl Hewitt|url= http://biography.carlhewitt.info|year= 2007|access-date= 2007-11-22|archive-url= https://web.archive.org/web/20090907130622/http://biography.carlhewitt.info/|archive-date= 2009-09-07|url-status= dead}}</ref>


From September 1989 to August 1990, Hewitt was the ''IBM Chair Visiting Professor'' in the Department of Computer Science at ] in Japan.<ref>{{cite web|author = Ryuichiro Ohyama |title= Department of Computer Science-Recent and Current Visiting Professors|url = http://www.cs.keio.ac.jp/DCS/Visit.html|year= 1991|accessdate = 2007-06-19}}</ref> From September 1989 to August 1990, Hewitt was the IBM Chair Visiting Professor in the Department of Computer Science at ] in Japan.<ref>{{cite web|author= Ryuichiro Ohyama|title= Department of Computer Science-Recent and Current Visiting Professors|url= http://www.cs.keio.ac.jp/DCS/Visit.html|year= 1991|access-date= 2007-06-19|archive-url= https://web.archive.org/web/20070430231715/http://cs.keio.ac.jp/DCS/Visit.html|archive-date= 2007-04-30|url-status= dead}}</ref> He has also been a visiting professor at ].


== Research == == Research ==
Hewitt was best known for his work on the ] of computation. For the last decade, his work had been in "inconsistency robustness", which aims to provide practical rigorous foundations for systems dealing with pervasively inconsistent information.<ref>{{cite book | title=Inconsistency Robustness | editor1-last=Hewitt | editor1-first=Carl | editor2-last=Woods | editor2-first=John | publisher=College Publications | year=2015 | isbn=9781848901599 | pages=614 | volume=52 | series=Studies in Logic}}</ref> This work grew out of his doctoral dissertation focused on the procedural (as opposed to logical) embedding of knowledge, which was embodied in the ].
Hewitt's research has spanned a range of topics generally concerning the Procedural Embedding of Knowledge.

His publications also include contributions in the areas of ],<ref name="Hewitt1986">{{cite journal|author=Carl Hewitt|title=Offices Are Open Systems|journal=ACM Trans. Inf. Syst. |volume=4 |issue=3 |pages=271–287|year=1986|doi=10.1145/214427.214432|s2cid=18029528|doi-access=free}}</ref> organizational and ]s,<ref>{{cite book|author=Jacques Ferber|title=Multi-Agent Systems: An Introduction to Distributed Artificial Intelligence|publisher=Addison-Wesley|year=1999}}</ref> ],<ref name="hewitt69"/> ], ]<ref name="Hewitt2008">{{Cite book |first=Carl|last=Hewitt|chapter-url=http://carlhewitt.blogspot.com/2008/08/large-scale-organizational-computing.html |chapter = Large-scale Organizational Computing requires Unstratified Reflection and Strong Paraconsistency|publisher=Springer-Verlag|year=2008|title=Coordination, Organizations, Institutions, and Norms in Agent Systems III|editor-first=Jaime|editor-last=Sichman|editor2-first=Pablo|editor2-last=Noriega|editor3-first=Julian|editor3-last=Padget|editor4-first=Sascha|editor4-last=Ossowski|isbn=978-3-540-79002-0}}</ref> and ].<ref>{{cite journal|author=Carl Hewitt|title=ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing|journal=IEEE Internet Computing|volume=12|issue=5|date=September–October 2008}}</ref>


===Planner=== ===Planner===
{{main|Planner (programming language)}} {{Main|Planner (programming language)}}
The Planner language was developed during the late 1960s as part of Hewitt's doctoral research in MIT's Artificial Intelligence Laboratory. Hewitt's work on Planner introduced the notion of the "procedural embedding of knowledge",<ref>Carl Hewitt. ''Procedural Embedding of Knowledge In Planner'' IJCAI. 1971.</ref> which was an alternative to the logical approach to knowledge encoding for ] pioneered by ].<ref>Philippe Rouchy, , TeamEthno-Online Issue 2, June 2006, 85-100.</ref> Planner has been described as "extremely ambitious".<ref name="sussman1998">{{cite journal|last=Sussman|first=Gerald Jay|coauthors=Guy L. Steele|date=1998|title=The First Report on Scheme Revisited |journal=Higher-Order and Symbolic Computation|publisher=Kluwer Academic Publishers|location=Boston|volume=11|pages=399–404|language=English|url=http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|accessdate=2009-01-03}}</ref> A subset of Planner called Micro-Planner was implemented at MIT by ], ], ] and ] <ref name="SussmanWinograd">Gerry Sussman and Terry Winograd. '''' AI Memo No, 203, MIT Project MAC, July 1970.</ref> and was used in Winograd's famous ] program, <ref name="Winograd">Terry Winograd. '''' MIT AI TR-235. January 1971.</ref> Charniak's natural language story understanding work, <ref name="MinskyPapert">Marvin Minsky and Seymour Papert. “Progress Report on Artificial Intelligence” MIT AI Memo 252. 1971.</ref> and L. Thorne McCarty's work on legal reasoning. <ref>L. Thorne McCarty. "Reflections on TAXMAN: An Experiment on Artificial Intelligence and Legal Reasoning" Harvard Law Review. Vol. 90, No. 5, March 1977</ref> Planner was almost completely implemented in Popler<ref name="Davies">Julian Davies. Popler 1.6 Reference Manual University of Edinburgh, TPU Report No. 1, May 1973.</ref> by Julian Davies at Edinburgh, where (together with earlier work at Edinburgh on Pico-Planner by Bruce Anderson<ref>Bruce Anderson. Documentation for LIB PICO-PLANNER School of Artificial Intelligence, Edinburgh University. 1972.</ref>) it influenced ] and ] in the development of ideas that later became ].<ref></ref><ref>Robert Kowalski Predicate Logic as Programming Language IFIP'74.</ref> Planner also influenced the later development of other AI research languages such as Muddle, Micro-Planner, and Conniver,<ref name="sussman1998"/> as well as the ] object-oriented programming language.<ref name="kay2003">{{cite web|url=http://www.purl.org/stefan_ram/pub/doc_kay_oop_en|title=E-Mail of 2003-07-23|last=Kay|first=Alan|coauthors=Stefan Ram|date=2003-07-23|work=Dr. Alan Kay on the Meaning of “Object-Oriented Programming”|language=English|accessdate=2009-01-03}}</ref> Planner's seminal influence has been cited by ]<ref>John McCarthy. Sterile Containers www.ai.sri.com/~rkf/designdoc/sterile.ps September 8, 2000.</ref> and ]<ref>Nils Nilsson Artificial Intelligence: A New Synthesis San Francisco: Morgan Kaufmann, 1998.</ref>. The Planner language was developed during the late 1960s as part of Hewitt's doctoral research in MIT's Artificial Intelligence Laboratory. Hewitt's work on Planner introduced the notion of the "procedural embedding of knowledge",<ref>Carl Hewitt. ''Procedural Embedding of Knowledge In Planner'' IJCAI. 1971.</ref> which was an alternative to the logical approach to knowledge encoding for ] pioneered by ].<ref>Philippe Rouchy, , TeamEthno-Online Issue 2, June 2006, 85-100.</ref> Planner has been described as "extremely ambitious".<ref name="sussman1998">{{cite journal|doi=10.1023/A:1010079421970|last=Sussman|first=Gerald Jay|author2=Guy L. Steele|year=1998|title=The First Report on Scheme Revisited|journal=Higher-Order and Symbolic Computation|volume=11|pages=399–404|url=http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|access-date=2009-01-03|issue=4|s2cid=7704398|url-status=dead|archive-url=https://web.archive.org/web/20060615225746/http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|archive-date=2006-06-15}}</ref> A subset of Planner called Micro-Planner was implemented at MIT by ], ], ] and ]<ref name="SussmanWinograd">Gerry Sussman and Terry Winograd. '''' AI Memo No, 203, MIT Project MAC, July 1970.</ref> and was used in Winograd's ] program,<ref name="Winograd">Terry Winograd. '''' MIT AI TR-235. January 1971.</ref> Charniak's natural language story understanding work,<ref name="MinskyPapert">Marvin Minsky and Seymour Papert. "Progress Report on Artificial Intelligence" MIT AI Memo 252. 1971.</ref> and L. Thorne McCarty's work on legal reasoning.<ref>L. Thorne McCarty. "Reflections on TAXMAN: An Experiment on Artificial Intelligence and Legal Reasoning" Harvard Law Review. Vol. 90, No. 5, March 1977</ref> Planner was almost completely implemented in Popler<ref name="Davies">Julian Davies. Popler 1.6 Reference Manual University of Edinburgh, TPU Report No. 1, May 1973.</ref> by Julian Davies at Edinburgh. Planner also influenced the later development of other AI research languages such as Muddle and Conniver,<ref name="sussman1998"/> as well as the ] object-oriented programming language.<ref name="kay2003">{{cite web|url=http://www.purl.org/stefan_ram/pub/doc_kay_oop_en|title=E-Mail of 2003-07-23|last=Kay|first=Alan|author2=Stefan Ram|date=2003-07-23|work=Dr. Alan Kay on the Meaning of "Object-Oriented Programming"|access-date=2009-01-03}}</ref>


Hewitt's own work on Planner continued with ] (later called MDL), which was developed in the early 1970s by Sussman, Hewitt, Chris Reeve, and David Cressey as a stepping-stone towards a full implementation of Planner. Muddle was implemented as an extended version of ], and introduced several features that were later adopted by Conniver, Lisp Machine Lisp, and Common Lisp.<ref name="sussman1998"/> However, in late 1972 Hewitt abruptly halted his development of the Planner design in his thesis, when he and his graduate students invented the ] of computation. Hewitt's own work on Planner continued with ] (later called MDL), which was developed in the early 1970s by Sussman, Hewitt, Chris Reeve, and David Cressey as a stepping-stone towards a full implementation of Planner. Muddle was implemented as an extended version of ], and introduced several features that were later adopted by Conniver, Lisp Machine Lisp, and Common Lisp.<ref name="sussman1998"/> However, in late 1972 Hewitt abruptly halted his development of the Planner design in his thesis, when he and his graduate students invented the ] of computation.


=== Actor model === === Actor model ===
{{main|Actor model}} {{Main|Actor model}}
Hewitt's work on the ] of computation has spanned over 30 years, beginning with the introduction of the model in a 1973 paper authored by Hewitt, Peter Bishop, and Richard Steiger,<ref name="hewitt1973">{{cite paper|author=Carl Hewitt|coauthors=Peter Bishop and Richard Steiger|title=A Universal Modular Actor Formalism for Artificial Intelligence|publisher=IJCAI|year=1973}}</ref> and including new results on Actor model semantics published as recently as 2006.<ref name="hewitt2006">Carl Hewitt COIN@AAMAS. April 27, 2006.</ref> Much of this work was carried out in collaboration with students in Hewitt's Message Passing Semantics Group at MIT's Artificial Intelligence Lab.<ref name="miller">{{cite web|author=Mark S. Miller|title = Actors: Foundations for Open Systems| url=http://www.erights.org/history/actors.html |accessdate=2007-06-20}}</ref> Hewitt's work on the ] of computation spanned over 30 years, beginning with the introduction of the model in a 1973 paper authored by Hewitt, Peter Bishop, and Richard Steiger,<ref name="hewitt1973">{{cite conference |url=https://www.ijcai.org/Proceedings/73/Papers/027B.pdf |title=A Universal Modular Actor Formalism for Artificial Intelligence |last1=Hewitt |first1=Carl |author-link1=Carl Hewitt |last2=Bishop |first2=Peter |last3=Steiger |first3=Richard |date=1973 |conference=International Joint Conference on Artificial Intelligence}}</ref> and including new results on actor model semantics published as recently as 2006.<ref name="hewitt2006">Carl Hewitt COIN@AAMAS. April 27, 2006.</ref> Much of this work was carried out in collaboration with students in Hewitt's Message Passing Semantics Group at MIT's Artificial Intelligence Lab.<ref name="miller">{{cite web|author=Mark S. Miller|title = Actors: Foundations for Open Systems| url=http://www.erights.org/history/actors.html |access-date=2007-06-20}}</ref>


] and ] developed the ] in an effort to gain a better understanding of the Actor model. However, their Scheme interpreter was not capable of fully implementing the Actor model because it did not include primitives for representing synchronizers or mutable cells.<ref>{{cite journal|last=Sussman|first=Gerald Jay|coauthors=Guy L. Steele|date=1998|title=The First Report on Scheme Revisited |journal=Higher-Order and Symbolic Computation|publisher=Kluwer Academic Publishers|location=Boston|volume=11|pages=399–404|language=English|url=http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|accessdate=2009-01-03|quote=We concluded that actors and closures were effectively the same concept. (Hewitt later agreed with this, but noted that two types of primitive actors in his theory, namely cells (which have modifiable state) and synchronizers (which enforce exclusive access), cannot be expressed as closures in a lexically scoped pure Lisp without adding equivalent primitive extensions.)}}</ref> A number of programming languages were developed to specifically implement the Actor model, such as ACT-1,<ref>Henry Lieberman, "", In Object-Oriented Concurrent Programming, A. Yonezawa and M. Tokoro, eds., MIT Press, 1987.</ref> ],<ref>C. Varela and G. Agha. . OOPSLA 2001 Intriguing Technology Track. ACM SIGPLAN Notices, 36(12):20-34, December 2001.</ref> Caltrop,<ref>{{cite paper|author=Johan Eker|coauthors=Jörn W. Janneck|title= An introduction to the Caltrop actor language |url = http://embedded.eecs.berkeley.edu/caltrop/docs/CaltropWhitePaper.pdf|format=PDF| accessdate = 2007-06-20}}</ref>, ]<ref name="miller2006"/> and ActorScript<ref name="Hewitt2008b"/>. The Actor model also influenced the development of the ].<ref>Robin Milner Elements of interaction: Turing award lecture CACM. January 1993.</ref> (See ].) ] and ] developed the ] in an effort to gain a better understanding of the actor model. They discovered that their operator to create an actor, ALPHA, and their operator to create a function, LAMBDA, were identical, so they only kept LAMBDA for both.<ref name="Actors">{{cite arXiv | author=Hewitt, Carl| title=Actor Model of computation | eprint= 1008.1459 | class=cs.PL | year=2010}}</ref><ref>{{cite journal|doi=10.1023/A:1010079421970|last=Sussman|first=Gerald Jay|author2=Guy L. Steele|year=1998|title=The First Report on Scheme Revisited|journal=Higher-Order and Symbolic Computation|volume=11|pages=399–404|url=http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|issue=4|s2cid=7704398|url-status=dead|archive-url=https://web.archive.org/web/20060615225746/http://www.brics.dk/~hosc/local/HOSC-11-4-pp399-404.pdf|archive-date=2006-06-15}}</ref> A number of other programming languages were developed to specifically implement the actor model, such as ACT-1,<ref>Henry Lieberman, "", In Object-Oriented Concurrent Programming, A. Yonezawa and M. Tokoro, eds., MIT Press, 1987.</ref> ],<ref>C. Varela and G. Agha. . OOPSLA 2001 Intriguing Technology Track. ACM SIGPLAN Notices, 36(12):20-34, December 2001.</ref> Caltrop,<ref>{{cite web |url=https://ptolemy.berkeley.edu/projects/embedded/caltrop/docs/CaltropWhitePaper.pdf |title=An introduction to the Caltrop actor language |last=Eker |first=Johan |last2=Janneck |first2=Jörn W. |date=2001-11-28 |access-date=2007-06-20}}</ref> ]<ref name="miller2006"/> and ActorScript.<ref name="ActorScript">{{cite arXiv | author=Hewitt, Carl| title=ActorScript extension of C#, Java, andObjective C| eprint=1008.2748 | class=cs.PL | year=2010 }}</ref> The actor model also influenced the development of the ].<ref>Robin Milner Elements of interaction: Turing award lecture CACM. January 1993.</ref> (See ].)


==Selected works== ==Selected works==
*Carl Hewitt (1969). IJCAI'69. * Carl Hewitt (1969). IJCAI'69.
*Carl Hewitt, Peter Bishop and Richard Steiger (1973). ''A Universal Modular Actor Formalism for Artificial Intelligence'' IJCAI'73. * Carl Hewitt, Peter Bishop and Richard Steiger (1973). IJCAI'73.
*Carl Hewitt and ] (1977a). ''Laws for Communicating Parallel Processes'' IFIP'77. * Carl Hewitt and ] (1977a). ''Laws for Communicating Parallel Processes'' IFIP'77.
*Carl Hewitt and ] (1977b). Proceeding of IFIP Working Conference on Formal Description of Programming Concepts. August 1&ndash;5, 1977. * Carl Hewitt and ] (1977b). Proceeding of IFIP Working Conference on Formal Description of Programming Concepts. August 1–5, 1977.
*William Kornfeld and Carl Hewitt (1981). IEEE Transactions on Systems, Man, and Cybernetics. January 1981. * William Kornfeld and Carl Hewitt (1981). IEEE Transactions on Systems, Man, and Cybernetics. January 1981.
* Henry Lieberman and Carl E. Hewitt (1983). Communications of the ACM, 26(6). * Henry Lieberman and Carl E. Hewitt (1983). Communications of the ACM, 26(6).
*Carl Hewitt (1985). ''The Challenge of Open Systems'' Byte Magazine. April 1985. (Reprinted in ''The foundation of artificial intelligence--a sourcebook'' Cambridge University Press. 1990) * Carl Hewitt (1985). ''The Challenge of Open Systems'' Byte Magazine. April 1985. (Reprinted in ''The foundation of artificial intelligence—a sourcebook'' Cambridge University Press. 1990

⚫ ==References==
⚫ {{reflist|2}}


==See also== ==See also==
* ] * ]

⚫ ==References==
⚫ {{reflist|30em}}


==External links== ==External links==
* {{DBLP|Hewitt:Carl|h}} * {{DBLP |name=Carl Hewitt}}
* {{MathGenealogy |name=Carl Eddie Hewitt}}
* .
* . *

* .
{{Authority control}}
* conducted by ] on November 18, 2008.
* on October 22, 2008.
* conducted by on October 28, 2008.
<!-- Metadata: see ] -->


{{Persondata
|NAME= Hewitt, Carl
|ALTERNATIVE NAMES=
|SHORT DESCRIPTION= ] mathematician and computer scientist
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Latest revision as of 23:49, 10 October 2024

American computer scientist; Planner programming languagedesigner (1944-2022)

Carl Hewitt
Carl Hewitt in 2008
Born1944 (1944)
Died (aged 77)
Aptos, California
Alma materMIT
Known forActor model
Inconsistency robustness
Planner (logic programs)
Comparative schematology
Scientific career
FieldsComputer science
Mathematical logic
Model of computation
Programming languages
Philosophy of logic
InstitutionsMIT
Keio University
Stanford University
Doctoral advisorSeymour Papert
Other academic advisorsMarvin Minsky
Mike Paterson
Doctoral studentsGul Agha
Henry Baker
William Clinger
Irene Greif
Akinori Yonezawa

Carl Eddie Hewitt (/ˈhjuːɪt/; 1944 – 7 December 2022) was an American computer scientist who designed the Planner programming language for automated planning and the actor model of concurrent computation, which have been influential in the development of logic, functional and object-oriented programming. Planner was the first programming language based on procedural plans invoked using pattern-directed invocation from assertions and goals. The actor model influenced the development of the Scheme programming language, the π-calculus, and served as an inspiration for several other programming languages.

Education and career

Hewitt obtained his PhD in mathematics at MIT in 1971, under the supervision of Seymour Papert, Marvin Minsky, and Mike Paterson. He began his employment at MIT that year, and retired from the faculty of the MIT Department of Electrical Engineering and Computer Science during the 1999–2000 school year. He became emeritus in the department in 2000. Among the doctoral students that Hewitt supervised during his time at MIT are Gul Agha, Henry Baker, William Clinger, Irene Greif, and Akinori Yonezawa.

From September 1989 to August 1990, Hewitt was the IBM Chair Visiting Professor in the Department of Computer Science at Keio University in Japan. He has also been a visiting professor at Stanford University.

Research

Hewitt was best known for his work on the actor model of computation. For the last decade, his work had been in "inconsistency robustness", which aims to provide practical rigorous foundations for systems dealing with pervasively inconsistent information. This work grew out of his doctoral dissertation focused on the procedural (as opposed to logical) embedding of knowledge, which was embodied in the Planner programming language.

His publications also include contributions in the areas of open information systems, organizational and multi-agent systems, logic programming, concurrent programming, paraconsistent logic and cloud computing.

Planner

Main article: Planner (programming language)

The Planner language was developed during the late 1960s as part of Hewitt's doctoral research in MIT's Artificial Intelligence Laboratory. Hewitt's work on Planner introduced the notion of the "procedural embedding of knowledge", which was an alternative to the logical approach to knowledge encoding for artificial intelligence pioneered by John McCarthy. Planner has been described as "extremely ambitious". A subset of Planner called Micro-Planner was implemented at MIT by Gerry Sussman, Drew McDermott, Eugene Charniak and Terry Winograd and was used in Winograd's SHRDLU program, Charniak's natural language story understanding work, and L. Thorne McCarty's work on legal reasoning. Planner was almost completely implemented in Popler by Julian Davies at Edinburgh. Planner also influenced the later development of other AI research languages such as Muddle and Conniver, as well as the Smalltalk object-oriented programming language.

Hewitt's own work on Planner continued with Muddle (later called MDL), which was developed in the early 1970s by Sussman, Hewitt, Chris Reeve, and David Cressey as a stepping-stone towards a full implementation of Planner. Muddle was implemented as an extended version of Lisp, and introduced several features that were later adopted by Conniver, Lisp Machine Lisp, and Common Lisp. However, in late 1972 Hewitt abruptly halted his development of the Planner design in his thesis, when he and his graduate students invented the actor model of computation.

Actor model

Main article: Actor model

Hewitt's work on the actor model of computation spanned over 30 years, beginning with the introduction of the model in a 1973 paper authored by Hewitt, Peter Bishop, and Richard Steiger, and including new results on actor model semantics published as recently as 2006. Much of this work was carried out in collaboration with students in Hewitt's Message Passing Semantics Group at MIT's Artificial Intelligence Lab.

Sussman and Steele developed the Scheme programming language in an effort to gain a better understanding of the actor model. They discovered that their operator to create an actor, ALPHA, and their operator to create a function, LAMBDA, were identical, so they only kept LAMBDA for both. A number of other programming languages were developed to specifically implement the actor model, such as ACT-1, SALSA, Caltrop, E and ActorScript. The actor model also influenced the development of the π-calculus. (See actor model and process calculi history.)

Selected works

See also

References

  1. "Carl Hewitt Obituary (1944 - 2022) - Aptos, CA - Santa Cruz Sentinel". Legacy.com.
  2. Carl Hewitt Stanford. 2022.
  3. ^ Carl Hewitt. PLANNER: A Language for Proving Theorems in Robots IJCAI. 1969.
  4. Filman, Robert; Daniel Friedman (1984). "Actors". Coordinated Computing - Tools and Techniques for Distributed Software. McGraw-Hill. p. 145. ISBN 978-0-07-022439-1. Retrieved 2007-04-22. Carl Hewitt and his colleagues at M.I.T. are developing the Actor model.
  5. Krishnamurthi, Shriram (December 1994). "An Introduction to Scheme". Crossroads. 1 (2): 19–27. doi:10.1145/197149.197166. S2CID 9782289. Archived from the original on 2007-04-25. Retrieved 2007-04-22.
  6. Milner, Robin (January 1993). "ACM Turing Award Lecture: The Elements of Interaction". Communications of the ACM. 36 (1): 78–89. doi:10.1145/151233.151240. S2CID 14586773.
  7. ^ Miller, Mark S. (2006). Robust Composition - Towards a Unified Approach to Access Control and Concurrency Control (PDF) (PhD). Johns Hopkins University. Archived from the original (PDF) on 2007-08-10. Retrieved 2007-05-26.
  8. MIT News Office (April 10, 1996). "Quarter Century Club inducts 73 new members". Retrieved 2007-06-19.
  9. John V. Guttag (2000). "MIT Reports to the President 1999–2000 – Department of Electrical Engineering and Computer Science". Retrieved 2007-06-19.
  10. "Stanford EE Computer Systems Colloquium". Stanford University. Retrieved 30 July 2011.
  11. Carl Hewitt (2007). "Academic Biography of Carl Hewitt". Archived from the original on 2009-09-07. Retrieved 2007-11-22.
  12. Ryuichiro Ohyama (1991). "Department of Computer Science-Recent and Current Visiting Professors". Archived from the original on 2007-04-30. Retrieved 2007-06-19.
  13. Hewitt, Carl; Woods, John, eds. (2015). Inconsistency Robustness. Studies in Logic. Vol. 52. College Publications. p. 614. ISBN 9781848901599.
  14. Carl Hewitt (1986). "Offices Are Open Systems". ACM Trans. Inf. Syst. 4 (3): 271–287. doi:10.1145/214427.214432. S2CID 18029528.
  15. Jacques Ferber (1999). Multi-Agent Systems: An Introduction to Distributed Artificial Intelligence. Addison-Wesley.
  16. Hewitt, Carl (2008). "Large-scale Organizational Computing requires Unstratified Reflection and Strong Paraconsistency". In Sichman, Jaime; Noriega, Pablo; Padget, Julian; Ossowski, Sascha (eds.). Coordination, Organizations, Institutions, and Norms in Agent Systems III. Springer-Verlag. ISBN 978-3-540-79002-0.
  17. Carl Hewitt (September–October 2008). "ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing". IEEE Internet Computing. 12 (5).
  18. Carl Hewitt. Procedural Embedding of Knowledge In Planner IJCAI. 1971.
  19. Philippe Rouchy, Aspects of PROLOG History: Logic Programming and Professional Dynamics, TeamEthno-Online Issue 2, June 2006, 85-100.
  20. ^ Sussman, Gerald Jay; Guy L. Steele (1998). "The First Report on Scheme Revisited" (PDF). Higher-Order and Symbolic Computation. 11 (4): 399–404. doi:10.1023/A:1010079421970. S2CID 7704398. Archived from the original (PDF) on 2006-06-15. Retrieved 2009-01-03.
  21. Gerry Sussman and Terry Winograd. Micro-planner Reference Manual AI Memo No, 203, MIT Project MAC, July 1970.
  22. Terry Winograd. Procedures as a Representation for Data in a Computer Program for Understanding Natural Language MIT AI TR-235. January 1971.
  23. Marvin Minsky and Seymour Papert. "Progress Report on Artificial Intelligence" MIT AI Memo 252. 1971.
  24. L. Thorne McCarty. "Reflections on TAXMAN: An Experiment on Artificial Intelligence and Legal Reasoning" Harvard Law Review. Vol. 90, No. 5, March 1977
  25. Julian Davies. Popler 1.6 Reference Manual University of Edinburgh, TPU Report No. 1, May 1973.
  26. Kay, Alan; Stefan Ram (2003-07-23). "E-Mail of 2003-07-23". Dr. Alan Kay on the Meaning of "Object-Oriented Programming". Retrieved 2009-01-03.
  27. Hewitt, Carl; Bishop, Peter; Steiger, Richard (1973). A Universal Modular Actor Formalism for Artificial Intelligence (PDF). International Joint Conference on Artificial Intelligence.
  28. Carl Hewitt What is Commitment? Physical, Organizational, and Social COIN@AAMAS. April 27, 2006.
  29. Mark S. Miller. "Actors: Foundations for Open Systems". Retrieved 2007-06-20.
  30. Hewitt, Carl (2010). "Actor Model of computation". arXiv:1008.1459 .
  31. Sussman, Gerald Jay; Guy L. Steele (1998). "The First Report on Scheme Revisited" (PDF). Higher-Order and Symbolic Computation. 11 (4): 399–404. doi:10.1023/A:1010079421970. S2CID 7704398. Archived from the original (PDF) on 2006-06-15.
  32. Henry Lieberman, "Concurrent Object-Oriented Programming in Act 1", In Object-Oriented Concurrent Programming, A. Yonezawa and M. Tokoro, eds., MIT Press, 1987.
  33. C. Varela and G. Agha. Programming Dynamically Reconfigurable Open Systems with SALSA. OOPSLA 2001 Intriguing Technology Track. ACM SIGPLAN Notices, 36(12):20-34, December 2001.
  34. Eker, Johan; Janneck, Jörn W. (2001-11-28). "An introduction to the Caltrop actor language" (PDF). Retrieved 2007-06-20.
  35. Hewitt, Carl (2010). "ActorScript extension of C#, Java, andObjective C". arXiv:1008.2748 .
  36. Robin Milner Elements of interaction: Turing award lecture CACM. January 1993.

External links

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