Random generation of associative algebras

Abstract

There has been considerable interest in recent decades in questions of random generation of finite and profinite groups, and finite simple groups in particular. In this paper we study similar notions for finite and profinite associative algebras. Let k = Fq be a finite field. Let A be a finite dimensional, associative, unital algebra over k. Let P (A) be the probability that two elements of A chosen (uniformly and independently) at random will generate A as a unital k-algebra. It is known that, if A is simple, then P (A) → 1 as |A| → ∞. We prove an analogue of this result for A an arbitrary finite associative algebra. For A simple, we find the lower bound for P (A) and we estimate the growth rate of P (A) in terms of the minimal index m(A) of any proper subalgebra of A. We also study the random generation of A by two elements that have a given characteristic polynomial (resp. a given rank). In addition, we bound above and below the minimal number of generators of A. Finally, we let A be a profinite algebra over k. We show that A is positively finitely generated if and only if A has polynomial maximal subalgebra growth. Related quantitative results are also established.