The Parafree Conjecture for Lie rings and associative algebras

Abstract

We construct a finitely generated parafree Lie ring with nonzero second homology and, over every nonzero commutative ring, a finitely generated parafree augmented associative algebra with nonzero second homology. These examples disprove the analogues of the Parafree Conjecture for Lie rings and for augmented associative algebras. Our constructions also provide finitely generated parafree examples that are not finitely presented, both in the Lie-ring and augmented-algebra settings.

arXiv comment22 pages; v2: added the case of Lie rings; comments are welcome!