## Persi Diaconis

### Mary V. Sunseri Professor of Statistics and Mathematics

Stanford University

## The Search for Randomness

### Monday, February 22, 2010

### 7-8:00PM

### 008 Kemeny Halll

**Abstract: **
I will take a careful look at some of our most primitive images of random phenomena; tossing a
coin, shuffling cards and throwing a dart at the wall. Analysis and practical experiments show that,
while approximate randomness is possible, usually we are lazy and things are quite far from random.
This reflects on the use (and misuse) of "statistical models" and the basic philosophy of randomness.

**Note:** This talk will be accessible to undergraduates.

**NB:** A PDF version of this announcement
(suitable for posting) is also available.

## Adding Numbers, Shuffling Cards and an Amazing Matrix

### Tuesday, February 23, 2010

### 4-5:00PM

### 007 Kemeny Hall

**Abstract: **
When several large numbers are added in the usual way, carries accrue along the way. It turns out
that the carries of "typical numbers" form a Markov Chain (Holte) with an "amazing" transition
matrix. This in turn is intimately related to the usual method of shuffling cards and several
other areas of mathematics. All of this is joint work with Jason Fulman.

**Note:** This talk will be accessible to undergraduate students.

## On Adding a List of Numbers (and other one dependent determinantal
processes)

### Wednesday, February 24, 2010

### 4:30-5:30PM

### 008 Kemeny Hall

**Abstract: **
There is mathematics to be found in the analysis of adding even a single column of numbers. The
carries along the way form a random process with fascinating properties. This makes a nice
introduction to processes that occur in random matrix theory. The results extend to group
extensions, Koszul algebras and many other areas. This is joint work with Alexi Borodin and Jason
Fulman.

**Note:** This talk will be accessible to graduate students.