English

Conjugacy classes in M\"obius groups

Geometric Topology 2013-08-14 v4 Group Theory

Abstract

Let \H^{n+1} denote the n+1n + 1-dimensional (real) hyperbolic space. Let \sn\s^{n} denote the conformal boundary of the hyperbolic space. The group of conformal diffeomorphisms of \sn\s^n is denoted by M(n)M (n). Let Mo(n)M_o (n) be its identity component which consists of all orientation-preserving elements in M(n)M (n). The conjugacy classification of isometries in Mo(n)M_o (n) depends on the conjugacy of TT and T1T^{-1} in Mo(n)M_o (n). For an element TT in M(n)M (n), TT and T1T^{-1} are conjugate in M(n)M (n), but they may not be conjugate in Mo(n)M_o (n). In the literature, TT is called real if TT is conjugate in Mo(n)M_o (n) to T1T^{-1}. In this paper we classify real elements in Mo(n)M_o (n). Let TT be an element in Mo(n)M_o(n). Corresponding to TT there is an associated element ToT_o in SO(n+1)SO(n+1). If the complex conjugate eigenvalues of ToT_o are given by {eiθj,eiθj}\{e^{i\theta_j}, e^{-i\theta_j}\}, 0<θjπ0 < \theta_j \leq \pi, j=1,...,kj=1,...,k, then {θ1,...,θk}\{\theta_1,...,\theta_k\} are called the \emph{rotation angles} of TT. If the rotation angles of TT are distinct from each-other, then TT is called a \emph{regular} element. After classifying the real elements in Mo(n)M_o (n) we have parametrized the conjugacy classes of regular elements in Mo(n)M_o (n). In the parametrization, when TT is not conjugate to T1T^{-1}, we have enlarged the group and have considered the conjugacy class of TT in M(n)M (n). We prove that each such conjugacy class can be induced with a fibration structure.

Keywords

Cite

@article{arxiv.0910.1909,
  title  = {Conjugacy classes in M\"obius groups},
  author = {Krishnendu Gongopadhyay},
  journal= {arXiv preprint arXiv:0910.1909},
  year   = {2013}
}

Comments

revised version.

R2 v1 2026-06-21T13:56:42.240Z