2008-2009

Timur Oikhberg

**Thursday, March 5
Davidson Lecture
Hall at Claremont McKenna, 4:00 PM**

Abstract:
We begin by showing that the restriction of an elementary Schur
multiplier with the symbol $(a_i b_j)$ to a coordinate subspace $S$ of
$B(l_2)$ (or, more generally, of a Schatten space) equals the supremum
of $|a_i b_j|$, taken over all pairs $(i,j)$ for which the matrix unit
$E_{ij}$ belongs to $S$. This result is applied to generalize
Wielandt's Minimax Principle for singular numbers. Further applications
include determining the membership of multiplication operators in
various operator ideals.