We have have encountered several finite groups in the previous chapter: the cyclic group Zn, the symmetric group Sn, and its subgroup the alternating group An. The properties of these groups will be elaborated in this chapter. We will also discuss three other groups obtained by incorporating ‘reflections’ into Zn, the dihedral group Dn, the generalized quaterion group Qn, and the dicyclic group...

a r t i c l e i n f o a b s t r a c t Let M be a countably infinite first order relational structure which is homogeneous in the sense of Fraïssé. We show, under the assumption that the class of finite substructures of M has the free amalgamation property, along with the assumption that Aut(M) is transitive on M but not equal to Sym(M), that Aut(M) is a simple group. This generalises results of...

In this note we discuss some symmetry groups as nice examples of group extensions. We begin by a short general discussion of symmetry groups. An isometry of R is a distancepreserving bijection of R. For examples of isometries, translations by a vector, rotations about a point, and reflections about a hyperplane are all isometries. Let Isom(R) be the set of all isometries of R. This is a group u...

A compact Klein surface with boundary of algebraic genus g ≥ 2 has at most 12(g−1) automorphisms. When a surface attains this bound, it has maximal symmetry, and the group of automorphisms is then called an M-group. If a finite group G of odd order acts on a bordered Klein surface X of algebraic genus g ≥ 2, then |G| ≤ 3(g − 1). If G acts with the largest possible order 3(g − 1), then G is call...