# 2003 DiPerna Lectures

*The 2003 DiPerna Memorial Lecture will be delivered by John Ball on January 30.*

Department of Mathematics, University of California, Berkeley, presents

The DiPerna Memorial Lecture 2003

**John Ball**

Oxford University & Institute for Advanced Study, Princeton

Thursday, January 30, 4 p.m.

60 EVANS

**The Regularity of Minimizers in Elasticity**

It is a major open problem of nonlinear elasticity theory to decide
whether or not energy minimizers are smooth or can have singularities.
Although some singular minimizers related to phase transformations or
fracture are known, there remains the possibility that there is a large
class of realistic stored-energy functions for which minimizers are
smooth. On the other hand there is apparently not a single example
known of a stored-energy function for which smoothness can be proved for
arbitrary large boundary data. The talk will survey what is known
about this problem, and about related questions such as satisfaction of
the Euler-Lagrange equation and uniform positivity of the Jacobian.

*Refreshments will be served in 1015 Evans, 3:00-4:00 pm*