Carl Hewitt is Board Chair of the International Society for Inconsistency Robustness. He has been a Visiting Professor at Stanford University and the University of Keio. In 2000, he became emeritus in the EECS department at MIT.
Hewitt is known for his design of Planner. This was the first programming language based on procedural plans invoked using pattern-directed invocation from assertions and goals. Planner was influential in the development of both logic programming and object-oriented programming. He is also known for his work on the Actor model of concurrent computation, which influenced the development of the Scheme programming language and the π calculus, and served as an inspiration for several other programming languages. His publications also include contributions in the areas of open information systems, organizational and multi-agent systems, logic programming, concurrent programming languages, direct inference, client cloud computing. His Erdős number is 3 (by two different co-authors).
Education and career
Hewitt obtained his PhD in mathematics at MIT in 1971, under the supervision of Seymour Papert, Marvin Minsky, and Mike Paterson. Hewitt started his employment at MIT in 1971. He retired from the faculty of the MIT Department of Electrical Engineering and Computer Science during the 1999-2000 school year. Among the doctoral students that Hewitt supervised during his time at MIT are Professor Gul Agha, Dr. Russell Atkinson, Dr. Henry Baker, 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 Akinori Yonezawa.
Hewitt's research has spanned a range of topics generally concerning the Procedural Embedding of Knowledge.
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 famous 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, where (together with earlier work at Edinburgh on Pico-Planner by Bruce Anderson) it influenced Robert Kowalski and Pat Hayes in the development of ideas that later became Prolog. 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. Planner's seminal influence has been cited by John McCarthy and Nils Nilsson.
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.
Hewitt's work on the Actor model 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, 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. However, their Scheme interpreter was not capable of fully implementing the Actor model because Actor customers cannot be implemented as lambda calculus continuations and Actors can change their local state in a way that is impossible in the lambda calculus  A number of 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.)
Client cloud computing
In recent years, Hewitt's research has concentrated on the area of client cloud computing in which computing is performed in client clouds and information is stored encrypted in data centers so that it can be decrypted only using the client's private key. His work on privacy aspects has been featured in O'Reilly Media. He has also done extensive work on client cloud information integration.
- Carl Hewitt (1969). PLANNER: A Language for Proving Theorems in Robots IJCAI'69.
- Carl Hewitt, Peter Bishop and Richard Steiger (1973). A Universal Modular Actor Formalism for Artificial Intelligence IJCAI'73.
- Carl Hewitt and Henry Baker (1977a). Laws for Communicating Parallel Processes IFIP'77.
- Carl Hewitt and Henry Baker (1977b). Actors and Continuous Functionals Proceeding of IFIP Working Conference on Formal Description of Programming Concepts. August 1–5, 1977.
- William Kornfeld and Carl Hewitt (1981). The Scientific Community Metaphor IEEE Transactions on Systems, Man, and Cybernetics. January 1981.
- Henry Lieberman and Carl E. Hewitt (1983). A Real-Time Garbage Collector Based on the Lifetimes of Objects 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's homepage". Retrieved 30 July 2011.
- "Stanford EE Computer Systems Colloquium". Standford University. Retrieved 30 July 2011.
- Carl Hewitt. PLANNER: A Language for Proving Theorems in Robots IJCAI. 1969.
- Hewitt, Carl (2010). "Actor Model of computation". arXiv:1008.1459 [cs.PL].
- Filman, Robert; Daniel Friedman (1984). "Actors". Coordinated Computing - Tools and Techniques for Distributed Software. McGraw-Hill. p. 145. ISBN 0-07-022439-0. "Carl Hewitt and his colleagues at M.I.T. are developing the Actor model."
- Krishnamurthi, Shriram (December 1994). "An Introduction to Scheme". Crossroads 1 (2): 19. doi:10.1145/197149.197166.
- Milner, Robin (January 1993). "ACM Turing Award Lecture: The Elements of Interaction" (PDF). Communications of the ACM 36 (1): 78. doi:10.1145/151233.151240.
- Mark S. Miller (2006). Robust Composition - Towards a Unified Approach to Access Control and Concurrency Control (PDF). PhD dissertation. Johns Hopkins University. Retrieved 2007-05-26.
- Carl Hewitt (1986). "Offices Are Open Systems". ACM Trans. Inf. Syst. 4 (3): 271–287. doi:10.1145/214427.214432.
- Jacques Ferber (1999). Multi-Agent Systems: An Introduction to Distributed Artificial Intelligence. Addison-Wesley.
- Carl Hewitt (2009). "Norms and Commitment for iOrgsTM Information Systems: Direct LogicTM and Participatory Grounding CheckingTM". arXiv:0906.2756 [cs.MA].
- Carl Hewitt (2009). "Middle History of Logic Programming: Resolution, Planner, Prolog and the Japanese Fifth Generation Project". arXiv:0904.3036 [cs.LO].
- Hewitt, Carl (2010). "ActorScriptTM extension of C#TM>, JavaTM, andObjective CTm". arXiv:1008.2748 [cs.PL].
- Hewitt, Carl (2008). "Large-scale Organizational Computing requires Unstratified Reflection and Strong Paraconsistency". In Sichman, Jaime; Noriega, Pablo; Padget, Julian et al. Coordination, Organizations, Institutions, and Norms in Agent Systems III. Springer-Verlag.
- Carl Hewitt (2008). "Common sense for concurrency and inconsistency tolerance using Direct Logic(TM) and the Actor Model". arXiv:0812.4852 [cs.LO].
- Carl Hewitt (September/October 2008). "ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing". IEEE Internet Computing 12 (5).
- Carl Hewitt (2009). "A historical perspective on developing foundations for privacy-friendly client cloud computing: iConsult(TM) apps using iDescribers(TM) Information Integration for iOrgs(TM) Information Systems". arXiv:0901.4934 [cs.DC].
- Carl Hewitt. "Intimate personal information in client-cloud aggregator datacenters is headed for strong government regulation".
- MIT News Office (April 10, 1996). "Quarter Century Club inducts 73 new members". Retrieved 2007-06-19.
- John V. Guttag (2000). "MIT Reports to the President 1999–2000 - Department of Electrical Engineering and Computer Science". Retrieved 2007-06-19.
- Carl Hewitt (2007). "Academic Biography of Carl Hewitt". Retrieved 2007-11-22.
- Ryuichiro Ohyama (1991). "Department of Computer Science-Recent and Current Visiting Professors". Retrieved 2007-06-19.
- Carl Hewitt. Procedural Embedding of Knowledge In Planner IJCAI. 1971.
- Philippe Rouchy, Aspects of PROLOG History: Logic Programming and Professional Dynamics, TeamEthno-Online Issue 2, June 2006, 85-100.
- Sussman, Gerald Jay; Guy L. Steele (1998). "The First Report on Scheme Revisited". Higher-Order and Symbolic Computation (Boston: Kluwer Academic Publishers) 11 (4): 399–404. doi:10.1023/A:1010079421970. Retrieved 2009-01-03.
- Gerry Sussman and Terry Winograd. Micro-planner Reference Manual AI Memo No, 203, MIT Project MAC, July 1970.
- Terry Winograd. Procedures as a Representation for Data in a Computer Program for Understanding Natural Language MIT AI TR-235. January 1971.
- Marvin Minsky and Seymour Papert. “Progress Report on Artificial Intelligence” MIT AI Memo 252. 1971.
- L. Thorne McCarty. "Reflections on TAXMAN: An Experiment on Artificial Intelligence and Legal Reasoning" Harvard Law Review. Vol. 90, No. 5, March 1977
- Julian Davies. Popler 1.6 Reference Manual University of Edinburgh, TPU Report No. 1, May 1973.
- Bruce Anderson. Documentation for LIB PICO-PLANNER School of Artificial Intelligence, Edinburgh University. 1972.
- Robert Kowalski Predicate Logic as Programming Language IFIP'74.
- 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.
- John McCarthy. Sterile Containers www.ai.sri.com/~rkf/designdoc/sterile.ps September 8, 2000.
- Nils Nilsson Artificial Intelligence: A New Synthesis San Francisco: Morgan Kaufmann, 1998.
- Carl Hewitt; Peter Bishop and Richard Steiger (1973). A Universal Modular Actor Formalism for Artificial Intelligence. IJCAI.
- Carl Hewitt What is Commitment? Physical, Organizational, and Social COIN@AAMAS. April 27, 2006.
- Mark S. Miller. "Actors: Foundations for Open Systems". Retrieved 2007-06-20.
- Sussman, Gerald Jay; Guy L. Steele (1998). "The First Report on Scheme Revisited". Higher-Order and Symbolic Computation (Boston: Kluwer Academic Publishers) 11 (4): 399–404. doi:10.1023/A:1010079421970.
- Henry Lieberman, "Concurrent Object-Oriented Programming in Act 1", In Object-Oriented Concurrent Programming, A. Yonezawa and M. Tokoro, eds., MIT Press, 1987.
- 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.
- Johan Eker; Jörn W. Janneck. An introduction to the Caltrop actor language (PDF). Retrieved 2007-06-20.
- Robin Milner Elements of interaction: Turing award lecture CACM. January 1993.
- Carl Hewitt (August 17, 2009). "Is intimate personal information a toxic asset in cloud data centers?". O'Reilly Radar.
- Intimate personal information in client-cloud aggregator datacenters is headed for strong government regulation
- Official website
- Carl Hewitt on Twitter
- List of publications from the DBLP Bibliography Server
- Wittgenstein versus Gödel on the Foundations of Logic Stanford hour-long video with slides here on April 23, 2010 with participants including Solomon Feferman, Jeremy Forth, Grigori Mints, and Charles Petrie.
- How to Program the Many Cores for Inconsistency Robustness Stanford hour-long video with slides here on January 12, 2011 with participants including Dennis Allison, Douglas Crockford, and Andy Freeman