Giuseppe GAETA 
Reduction and Equivariant Branching Lemma:
Dynamical Systems, Evolution PDEs, and Gauge Theories
(67K, Plain TeX)

ABSTRACT.  One of the simplest yet most useful tools in equivariant bifurcation theory is
the so called "Equivariant Branching Lemma" (EBL in the following) of Cicogna
nad Vanderbauwhede. The purpose of the present note is to extend the EBL to
gauge symmetries and gauge-symmetric problems; this will be done by looking at
gauge symmetries as a specific class of Lie-point symmetries in an appropriate
space. We will also obtain a weaker result (reduction lemma) for
evolution PDEs.