# School of Mathematics

## The mod $p$ derived spherical Hecke algebra: structure and applications

Abstract: I will introduce the mod p derived spherical Hecke algebra of a p-adic group, and discuss its structure via a derived version of the Satake homomorphism. Then, I will survey some speculations about its action on the cohomology of arithmetic manifolds.

## Algorithms for the topology of arithmetic groups and Hecke actions

Abstract: We will describe new algorithms to compute an explicit finite simplicial model for compact, congruence locally symmetric spaces and Hecke actions thereon. Joint work with Aurel Page.

## Language edit distance, $(\min,+)$-matrix multiplication & beyond

The language edit distance is a significant generalization of two basic problems in computer science: parsing and string edit distance computation. Given any context free grammar, it computes the minimum number of insertions, deletions and substitutions required to convert a given input string into a valid member of the language. In 1972, Aho and Peterson gave a dynamic programming algorithm that solves this problem in time cubic in the string length. Despite its vast number of applications, in forty years there has been no improvement over this running time.