Bases for Primitive Permutation Groups and a Conjecture of Babai

Bases for Primitive Permutation Groups and a Conjecture of Babai

A base of a permutation group G is a sequence B of points from the permutation domain such that only the identity of G fixes B pointwise. We show that primitive permutation groups with no alternating composition factors of degree greater than d and no classical composition factors of rank greater than d have a base of size bounded above by a function of d. This confirms a conjecture of Babai. Q...

Distinguishing Primitive Permutation Groups

Let G be a permutation group acting on a set V . A partition π of V is distinguishing if the only element of G that fixes each cell of π is the identity. The distinguishing number of G is the minimum number of cells in a distinguishing partition. We prove that if G is a primitive permutation group and |V | ≥ 336, its distinguishing number is two.

Factorizations of Primitive Permutation Groups

Bases for structures and permutation groups

Bases, determining sets, metric dimension, . . . The notion of a base, and various combinatorial variants on it, have been rediscovered many times in different parts of combinatorics, especially graph theory: base size has been called fixing number, determining number, rigidity index, etc. Robert Bailey and I have written a survey paper attempting to describe all these and related concepts and ...

On the Orders of Primitive Permutation Groups

The problem of bounding the order of a permutation group G in terms of its degree n was one of the central problems of 19th century group theory (see [4]). It is closely related to the 1860 Grand Prix problem of the Paris Academy, but its history goes in fact much further back (see e.g. [3], [1] and [10]). The heart of the problem is of course the case where G is a primitive group. The best res...