# Moyal Medallist 2014

## Moyal Medallist 2014

The 2014 Moyal Medallist is Professor Richard Brent FAA, Emeritus Professor of Mathematics at the Australian National University and Vice-Chancellor’s Visiting Fellow at the University of Newcastle. Prof. Brent will deliver the 2014 Moyal Lecture:

### Macquarie University: E7B T2 Lecture Theatre access via level 3 of building E7B

How to get there See M20 on campus map. Parking:- fees apply for casual parking (coins and credit cards accepted. W4, X3 and X4 car parks are designated for casula parking.

### Title: Needles, haystacks and optimal designs

#### Abstract:

Solving a mathematical problem is often analogous to finding a needle in a haystack. We may know that the needle is there, but finding it by checking each bale of hay would take a very long time. The lecture will give examples from several areas of mathematics, including primality testing, finding bounds on Ramsey numbers, and finding almost-optimal designs. Primality testing involves testing if a (large) integer is prime. One of its applications is to the popular RSA public-key cryptosystem, which needs primes with several hundred digits to ensure its security. Ramsey numbers are related to the ‘party problem’. A small example to illustrate this is: if I invite six people to a party, then surely at least three will know each other, or at least three will not know each other. D-optimal designs are used in the design of experiments to maximise the amount of information that can be obtained from the experiment. Mathematically, they are n x n matrices whose elements are ±1 and whose determinant is maximal. Finding them is very much like finding a needle in a haystack, because for most positive integers n the chance that a random n x n matrix has maximal determinant is extremely small. Nevertheless, it is possible to find almost-optimal designs efficiently by a probabilisitic algorithm. The talk is followed by a complimentary light supper in the tearoom E6B 2.300 (Dept of Physics & Astronomy multi purpose room). All are welcome.  For more information, please contact Maths Dept Administrator, Christine Hale (christine.hale@mq.edu.au). John Corbett Chair of the Moyal Medal Committee