NOTE TIME CHANGE FOT JANUARY 13 ONLY: SEMINAR AT 11 AM

The ferromagnetic Heisenberg model is conjectured to possess the
property of Ferromagnetic Ordering of Energy Levels (FOEL): the smallest
eigenvalues in the invariant subspaces of fixed total spin, S, are
monotonically decreasing in S. I will present a proof of this conjecture
for the one-dimensional case and discuss generalizations to other models
and several applications.