Finite primitive groups and regular orbits of group elements

Group Membership for Groups with Primitive Orbits

This paper considers a permutation group G = 〈S〉 of degree n with t orbits such that the action on each orbit is primitive. It presents a O(tn2 logc(n)) time Monte Carlo group membership algorithm for some constant c. The algorithm is notable for its use of a new theorem showing how to find O(t log n) generators in O (̃|S|n) time under a more general form of the above hypotheses. The algorithm r...

Regular Elements of Finite Reflection Groups

Regular Elements and Monodromy of Discriminants of Finite Reflection Groups

where the product is over all reflection hyperplanes of G. Let A : V/G -+ @ be the map induced by 6, thus A is the discriminant of G. A subgroup of G is called parabolic if it is generated by all reflections of G fixing elementwise a given subspace of V. The degrees of G are denoted by dl , d2, . . . , d,,. We call a degree of G primitive if it is bigger than the degrees of all proper parabolic...

Hilbert Functions of Finite Group Orbits: Abelian and Metacyclic Groups

This thesis is concerned with Hilbert functions of ideals of finite group orbits, focusing in particular on abelian and metacyclic groups. Conjecture 16 in Section 4 characterizes the Hilbert functions that arise from two-dimensional representations of certain abelian groups, and a proof of the necessity of its conditions is provided. In Section 6, Proposition 18 gives a bound for the Hilbert f...

Primitive central idempotents of finite group rings of symmetric groups

Let p be a prime. We denote by Sn the symmetric group of degree n, by An the alternating group of degree n and by Fp the field with p elements. An important concept of modular representation theory of a finite group G is the notion of a block. The blocks are in one-to-one correspondence with block idempotents, which are the primitive central idempotents of the group ring FqG, where q is a prime...