Giuseppe Gaeta Breaking of linear symmetries and Michel theory: degeneracy, Grassmann manifolds, and invariant subspaces (63K, plain TeX) ABSTRACT. Michel's theory of symmetry breaking in its original formulation has some difficulty in dealing with problems with a linear symmetry, due to the degeneration in the symmetry type implied by the linearity of group action. One can usually circumvent this difficultyu by quotienting out linear relations, but here we propose a more intrinsic, and fully geometric, approach to the problem, making use of Grassmann manifolds. In this way Michel theory can also be applied to the determination of dynamically invariant manifolds for equivariant nonlinear flows.