Some aspects of pregroups
A pregroup is a set A, equipped with a ternary operation \(\lambda\) : \(A\times A\times A\to A\), satisfying axioms \[ I.\quad \lambda (p,q,p)=q;\quad \lambda (p,p,q)=q \] \[ II.\quad \lambda (r,\lambda (p,q,r),t)=\lambda (p,q,t)\quad \lambda (q,t,\lambda (p,q,r))=\lambda (p,t,r). \] In this paper the author develops the subject algebraically by defining the notion of normal subpregroups, quotient pregroups, free pregroups, etc. Finally the author discusses the concept of normality ''based at a point''.
scientific article; zbMATH DE number 3955259