An artin algebra is called CM-free provided that all its finitely generated Gorenstein projective modules are projective. We show that a connected artin algebra with radical square zero is either self-injective or CM-free. As a consequence, we prove that a connected artin algebra with radical square zero is Gorenstein if and only if its valued quiver is either an oriented cycle with the trivial...

We give geometric constructions of families of graded Gorenstein Artin algebras, some of which span a component of the space Gor(T ) parametrizing Gorenstein Artin algebras with a given Hilbert function T . This gives a lot of examples where Gor(T ) is reducible. We also show that the Hilbert function of a codimension four Gorenstein Artin algebra can have an arbitrarily long constant part with...

We construct a quasi-Garside monoid structure for the free group. This monoid should be thought of as a dual braid monoid for the free group, generalising the constructions by Birman-Ko-Lee and by the author of new Garside monoids for Artin groups of spherical type. Conjecturally, an analog construction should be available for arbitrary Artin groups and for braid groups of well-generated comple...

Abstract. We define an Artin prime for an integer g to be a prime such that g is a primitive root modulo that prime. Let g ∈ Z \ {−1} and not be a perfect square. A conjecture of Artin states that the set of Artin primes for g has a positive density. In this paper we study a generalization of this conjecture for the primes produced by a polynomial and explore its connection with the problem of ...

We prove that every separated Artin stack of finite type over a noetherian base scheme admits a proper covering by a quasi–projective scheme. An application of this result is a version of the Grothendieck existence theorem for Artin stacks.

In this paper we will present the results of Artin– Markov on braid groups by using the Gröbner-Shirshov basis. As a consequence we can reobtain the normal form of Artin–Markov– Ivanovsky as an easy corollary.

In this paper we consider the class of 2–dimensional Artin groups with connected, large type, triangle-free defining graphs (type CLTTF). We classify these groups up to isomorphism, and describe a generating set for the automorphism group of each such Artin group. In the case where the defining graph has no separating edge or vertex we show that the Artin group is not abstractly commensurable t...