Multialgebra

Summary

A multialgebra is a set with multivalued operations. Each operation sends a tuple of elements to a nonempty set of elements, not to a single element. It generalises the algebraic structure of universal algebra, where each value is one element. Multialgebras include the hyperstructures such as hypergroups, and they appear when one passes to quotients, to sets of cosets, or to relations instead of functions.