Textbook of AI

1944–2022, Computer scientist, AI researcher

Also known as: Carl Eddie Hewitt

Carl Eddie Hewitt was an American computer scientist whose 1971 MIT PhD work produced PLANNER, a procedural-knowledge programming language used in Winograd's SHRDLU. PLANNER allowed knowledge to be expressed as procedures (a fact like "all dogs are mammals" became a recipe for proving "X is a mammal" by trying to prove "X is a dog"), an alternative to the declarative representations dominant in 1960s AI.

In 1973 he introduced the Actor model of concurrent computation: independent agents communicating only by asynchronous messages, with no shared state. The model, refined over decades with collaborators including Gul Agha and Henry Lieberman, anticipated and shaped object-oriented concurrency, the development of Erlang and Akka, and the actor-style architectures of modern cloud-native software. He spent his career at MIT.