# Prof Demonstrates Magic of Math

From teenage runaway to Stanford mathematics professor, Persi Diaconis’ life story may be even more unbelievable than the magic tricks he performs. Diaconis carried out a complicated card trick before providing a statistical explanation of it during the annual Kieval lecture, “Mathematics and Magic Tricks,” yesterday afternoon.

Beginning his talk with a magic trick, Diaconis threw a deck of cards into a packed Bache Auditorium, before ordering an audience member to cut the deck and select a card. He then told the participant to pass the deck around the crowd, so that five people held cards. Diaconis instructed the participants to stand up if they were holding a red card, before correctly predicting the cards four out of the five audience members were holding.

Diaconis then proceeded to break the first rule of magic: never reveal your secret. He explained that he had accurately guessed the cards using mathematical probability patterns with binary triples. Diaconis said this sequence is also found in random number generation by computers, repeated measurement and even robotic vision. It can also be used to manipulate DNA strand reading.

Diaconis began performing magic when he was only five years old at his mother’s day camp. When he was 14, he ran away from home to join a famous sleight-of-hand expert on the road. Although he did not know calculus, Diaconis attended night classes at the City College of New York to learn more about probability. To put himself through school, Diaconis performed magic tricks. After graduating in 1971, Diaconis obtained his masters and Ph.D. in mathematical statistics from Harvard.

Despite his love of magic, Diaconis still considers himself a mathematician at heart.

“Magic and math really are similar,” he said. “For both, you’re constantly solving problems under constraints. In magic, you want to solve a problem without the audience knowing how. In math, you need to solve problems following set rules.”

Yet Diaconis emphasized society’s perception of magicians and mathematicians as a key difference between the two professions. “Professors are treated with respect, but magicians may not be,” he said. “It’s a hard life.”

Diaconis encouraged students to follow their academic passions in creative ways, as he did.

“When you’re studying a subject, find another way to learn it [other than courses],” he said. “Get interested in something and just think about it. Learn about things you don’t take classes in.”

Besides his post at Stanford, Diaconis served as a research staff member at AT&T Bell laboratories, as well as a professor at Harvard.

From 1996-1998, he was Cornell’s David Duncan Professor of Mathematics. He is currently working on a book about math and magic with Ron Graham, professor of computer science at the University of California at San Diego, which he expects to complete within the next year.

Those that attended Diaconis’ lecture praised his enthusiasm and passion for both math and magic.

“I liked his sense of humor and he was very entertaining,” Peter Greczner ’09 said.

Cilanne Boulet, visiting assistant professor of mathematics, said, “It was a fun lecture and a good application of what [students] learn about in class.”

Archived article by Olivia Oran
Sun Staff Writer