Professor Raymond Smullyan, who taught at Lehman for nearly two decades, passed away on February 5 at the age of 97. He was in the Mathematics and Computer Science Department from 1968 to 1983, as well as the Philosophy Program at the Graduate center from 1976 to 1984. He was internationally known both as a mathematical logician and, thanks to his love of puzzles, an author of general interest books whose ideas took him to late night television.
As detailed in an extensive obituary in The New York Times, Prof. Smullyan was “a character. With his long white hair and beard, [he] resembled Ian McKellen’s wizard, Gandalf, from the The Lord of the Rings film series. He was lanky, hated exercise and loved steak and eggs.”
Smullyan was also a serious academic. He wrote several books and numerous research papers that have been influential—often in unexpected ways. His first book, Theory of Formal Systems (Princeton University Press, 1961), was a novel presentation of recursion theory, introducing ideas that became significant in automata theory, at the foundation of linguistics, and computer science. The book introduced a decidedly abstract approach to results about the foundations of mathematics. It also anticipated several of the ideas underlying the computer language, Prolog, developed much later for use in artificial intelligence.
His second book, First-Order Logic (Springer-Verlag; 1968) was an elegant presentation of formal logic, which impacted several generations in the field of automated theorem proving. The long-standing annual conference, Tableaux, which focuses on methods and programs in logic and mathematics, continues to have nearly every presentation feature a paper that is a direct or indirect descendent of First-Order Logic.
In the midst of his research on mathematical logic researches, Smullyan developed an interest in puzzles. This led him to author several books, including The Lady or the Tiger? (Knopf; 1983) which led readers through the basic ideas of Gödel’s famous incompleteness theorem, via a series of puzzles. That was followed by To Mock a Mockingbird (Knopf; 19850, which explored the Lambda-calculus via puzzles about birds. The Lambda calculus is a system of formal logic with applications to the design and semantics of computer languages. Smullyan’s book was of such interest that the automated theorem-proving group at Argonne National Laboratories once created a program specifically for solving his so-called bird puzzles.
Several of the books based on logic and puzzles were translated into other languages and have enjoyed worldwide popularity. As a result, Smullyan appeared on The Tonight Show with Johnny Carson and Firing Line with William F. Buckley, Jr.
Smullyan was also a classically trained pianist, and once worked professionally as a magician. His distinguished career is evidence of his being one of those rare persons who can work both sides of the street, popular and technical. His mathematical research still influences scholars; his general interest books make serious mathematics accessible and interesting to the talented amateur.
He will be missed deeply by those who knew him personally, and by the many who knew him through his writings.