Persi Warren Diaconis (; born January 31, 1945) is an American mathematician of Greek descent and former professional

magician Magician or The Magician may refer to: Performers * A practitioner of magic (supernatural) * A practitioner of magic (illusion) * Magician (fantasy), a character in a fictional fantasy context Entertainment Books * ''The Magician'', an 18th-ce ...

. He is the Mary V. Sunseri Professor of Statistics and Mathematics at Stanford University. He is particularly known for tackling mathematical problems involving randomness and randomization, such as

coin flipping Coin flipping, coin tossing, or heads or tails is the practice of throwing a coin in the air and checking which side is showing when it lands, in order to choose between two alternatives, heads or tails, sometimes used to resolve a dispute betw ...

and

shuffling playing cards Shuffling is a procedure used to randomize a deck of playing cards to provide an element of chance in card games. Shuffling is often followed by a cut, to help ensure that the shuffler has not manipulated the outcome. __TOC__ Techniques Overh ...

Biography

Diaconis left home at 14 to travel with

sleight-of-hand Sleight of hand (also known as prestidigitation or ''legerdemain'' ()) refers to fine motor skills when used by performing artists in different art forms to entertain or manipulate. It is closely associated with close-up magic, card magic, card ...

legend Dai Vernon, and dropped out of high school, returning to school at age 24 to learn math, motivated to read

William Feller William "Vilim" Feller (July 7, 1906 – January 14, 1970), born Vilibald Srećko Feller, was a Croatian-American mathematician specializing in probability theory. Early life and education Feller was born in Zagreb to Ida Oemichen-Perc, a C ...

's famous two-volume treatise on probability theory, ''An Introduction to Probability Theory and Its Applications''. He attended the

City College of New York The City College of the City University of New York (also known as the City College of New York, or simply City College or CCNY) is a public university within the City University of New York (CUNY) system in New York City. Founded in 1847, Cit ...

for his undergraduate work, graduating in 1971, and then obtained a Ph.D. in Mathematical Statistics from Harvard University in 1974), learned to read Feller, and became a mathematical probabilist.Jeffrey R. Young, "The Magical Mind of Persi Diaconis" ''Chronicle of Higher Education'' October 16, 201

/ref> According to Martin Gardner, at school, Diaconis supported himself by playing poker on ships between New York and South America. Gardner recalls that Diaconis had "fantastic

second deal The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each ...

and bottom deal". Diaconis is married to Stanford statistics professor Susan Holmes.

Career

Diaconis received a MacArthur Fellowship in 1982. In 1990, he published (with Dave Bayer) a paper entitled "Trailing the Dovetail Shuffle to Its Lair" (a term coined by magician Charles Jordan in the early 1900s) which established rigorous results on how many times a deck of playing cards must be riffle shuffled before it can be considered random according to the mathematical measure total variation distance. Diaconis is often cited for the simplified proposition that it takes seven shuffles to randomize a deck. More precisely, Diaconis showed that, in the

Gilbert–Shannon–Reeds model In the mathematics of shuffling playing cards, the Gilbert–Shannon–Reeds model is a probability distribution on riffle shuffle permutations that has been reported to be a good match for experimentally observed outcomes of human shuffling, and th ...

of how likely it is that a riffle results in a particular riffle shuffle permutation, it takes 5 riffles before the total variation distance of a 52-card deck begins to drop significantly from the maximum value of 1.0, and 7 riffles before it drops below 0.5 very quickly (a threshold phenomenon), after which it is reduced by a factor of 2 every shuffle. When entropy is viewed as the probabilistic distance, riffle shuffling seems to take less time to mix, and the threshold phenomenon goes away (because the entropy function is subadditive). Diaconis has coauthored several more recent papers expanding on his 1992 results and relating the problem of shuffling cards to other problems in mathematics. Among other things, they showed that the separation distance of an ordered

blackjack Blackjack (formerly Black Jack and Vingt-Un) is a casino banking game. The most widely played casino banking game in the world, it uses decks of 52 cards and descends from a global family of casino banking games known as Twenty-One. This fam ...

deck (that is, aces on top, followed by 2's, followed by 3's, etc.) drops below .5 after 7 shuffles. Separation distance is an upper bound for variation distance. Diaconis has been hired by casino executives to search for subtle flaws in their automatic card shuffling machines. Diaconis soon found some and the horrified executives responded, "We are not pleased with your conclusions but we believe them and that's what we hired you for." He served on the Mathematical Sciences jury of the Infosys Prize in 2011 and 2012.

Recognition

*1982 – Awarded a MacArthur Fellowship *1982 – Awarded the Rollo Davidson Prize *1990 – Invited Speaker of the International Congress of Mathematicians (ICM) *1995 – Elected to the National Academy of Sciences *1997 – Gibbs Lecturer, American Mathematical Society *1998 – Plenary Speaker of the ICM *2003 – Received an honorary D. Sci. degree from the University of Chicago. *2005 – Elected to the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

*2006 – Awarded the Van Wijngaarden Award *2012 – Awarded the Levi L. Conant Prize *2012 – Fellow of the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

*2013 – Received an Honorary Degree from the

University of St Andrews (Aien aristeuein) , motto_lang = grc , mottoeng = Ever to ExcelorEver to be the Best , established = , type = Public research university Ancient university , endowment ...

. *2014 – Recipient of Cahit Arf Lecture by Middle East Technical University, Ankara, Turkey

Works

The books written or coauthored by Diaconis include: * ''Group Representations In Probability And Statistics'' (Institute of Mathematical Statistics, 1988) * ''Magical Mathematics: The Mathematical Ideas That Animate Great Magic Tricks'' (with Ronald L. Graham, Princeton University Press, 2012), winner of the 2013 Euler Book Prize * ''Ten Great Ideas about Chance'' (with

Brian Skyrms Brian Skyrms (born 1938) is an American philosopher, Distinguished Professor of Logic and Philosophy of Science and Economics at the University of California, Irvine, and a professor of philosophy at Stanford University. He has worked on problem ...

, Princeton University Press, 2018)Reviews of ''Ten Great Ideas about Chance'': * * * * * * * * * * * * * His other publications include: *"Theories of data analysis: from magical thinking through classical statistics", in *

References

External links