Raymond Smullyan, 97; created logic puzzles

He was also a character. With his long white hair and beard, Dr. Smullyan resembled Ian McKellen’s wizard, Gandalf, from the “Lord of the Rings” film series. He hated exercise and loved steak and eggs. He studied Eastern religion. He told corny jokes and performed close-up magic to anyone near him. He played the piano with passion and talent into his 90s. (A career in music had been derailed by tendinitis when he was a young man.)

And he was fond of his philosophical, if silly, sayings, such as, “Why should I worry about dying? It’s not going to happen in my lifetime!”

Melvin Fitting, a retired professor of mathematics, philosophy, and computer science at the Graduate Center of the City University of New York, recalled Dr. Smullyan’s demeanor as his teacher at Yeshiva University in the 1960s.

“He’d be smiling in anticipation of the many beautiful things he was going to show you,” the professor said.

Dr. Smullyan saw beauty in the puzzles he created, seemingly nonstop, over the decades, and viewed them as tools to spread the gospel of mathematics. In his 1982 book “The Lady or the Tiger? And Other Logic Puzzles,” he wrote about the greater popularity Euclid’s “Elements” would have achieved had the Greek mathematician framed it as a puzzle book.

He wrote: “Problem: Given a triangle with two equal sides, are two of the angles necessarily equal? Why, or why not?”

His puzzles were so much a part of his identity that he posed one on his first date with his future wife, Blanche de Grab. He offered a statement that, in the way he framed it, could only result in a kiss from her. Reminiscing about it, he wrote that it was a “pretty sneaky way of winning a kiss, wasn’t it?”

Jason Rosenhouse, a mathematics professor at James Madison University, who edited a book in 2015 celebrating Dr. Smullyan, said the clarity of his puzzles could unveil the beauty of math to those who could not previously grasp it.

“It was like fooling a kid into eating his vegetables,” Rosenhouse said in an interview, adding, “Raymond took something like Godel’s incompleteness theorems and used a string of logic puzzles as a device for presenting them.”

Martin Gardner, himself a renowned math puzzler, compared Dr. Smullyan to the Oxford logician Charles Dodgson, who also was an author better known by his pen name, Lewis Carroll. Dr. Smullyan paid tribute to Carroll in his 1982 book “Alice in Puzzle-Land: A Carrollian Tale for Children Under Eighty.”

In one chapter, Dr. Smullyan wrote, Alice thinks to herself about how confusing, yet remarkably logical, Humpty Dumpty is. “I wonder,” she says, “how he manages to be both confusing and logical?”

There was, it would seem, some confusing logic in the zigzagging path of Dr. Smullyan’s life.

Raymond Merrill Smullyan was born in Queens, N.Y. His father, Isidore, was a businessman; his mother, the former Rosina Freedman, a homemaker. His education was peripatetic and eclectic. He attended Pacific University and Reed College in Oregon, then studied mathematics on his own. He created chess puzzles that were more concerned about moves that had been made than the ones that should be made.

He put together a magic act, and performed under the stage name Five-Ace Merrill at nightclubs like the Pump Room in Chicago, where he worked for tips. He earned a bachelor’s degree in mathematics from the University of Chicago and a PhD from Princeton. He taught at Princeton, Yeshiva, the City University of New York, and Indiana University.

His philosophy of teaching was a little puzzling. “My policy is to teach the student as much as possible and to require from him or her as little as possible,” he said in 2008.

But, he added, the effect of his apparent lenience was that many students worked harder in his course than in any other.