Paul Federbush
A Criterion for Ferromagnetism in the Isotropic
Quantum Heisenberg Model
(6K, LaTeX)

ABSTRACT.     A criterion for ferromagnetism is presented
suggesting a line of proof to rigorously establish
the phase transition. Spectral information will be
required in certain invariant subspaces of the
Hamiltonian, hopefully the relatively crude estimates
needed will be not too difficult to establish.