A generalization of Stallings' pregroup
A ``pree'' P is a nonempty set with a partial operation. The ``universal group'' G(P) of P is the group whose generators are the elements of P and defining relations come from the partial operation in P. If P can be embedded in G(P) then it is called by John R. Stallings a ``pregroup''. In this paper, the authors define a wider class of prees which are pregroups.
scientific article; zbMATH DE number 4077547
scientific article