One-relator groups with torsion are coherent

Abstract

We show that any one-relator group $G=F/⟨⟨w⟩⟩$ with torsion is coherent -- i.e., that every finitely generated subgroup of $G$ is finitely presented -- answering a 1974 question of Baumslag in this case.

11 pages, no figures. Version 2 incorporates the referee's comments, and corrects a mistake in Section 4. Version 3 is the final version accepted for publication