Equivariant degree for Abelian actions. III: Orthogonal maps
The paper represents the third part of the study of the equivariant degree for abelian actions. The authors study orthogonal equivariant maps, in particular gradients and Hamiltonians. Section 1 is devoted to the construction of the degree, first for gradients and then for orthogonal maps. Section 2 contains the main result. In Section 3, the authors extend the degree to infinite dimensions and compare it to the ``normal map'' approach. In Section 4, they compute the index of an isolated orbit and, in Section 5, they study bifurcation. Section 6 treats Hamiltonians. [For part I and II see the authors, ibid. 2, No. 2, 367-413 (1993; Zbl 0815.58004) and ibid. 7, No. 2, 369-430 (1996; Zbl 0899.58004)].
scientific article; zbMATH DE number 1370309
scientific article