Many-sorted unification

@article{Walther1988ManysortedU,
  title={Many-sorted unification},
  author={Christoph Walther},
  journal={J. ACM},
  year={1988},
  volume={35},
  pages={1-17}
}
Many-sorted unification is considered; that is, unification in the many-sorted free algebras of terms, where variables, as well as the domains and ranges of functions, are restricted to certain subsets of the universe, given as a potentially infinite hierarchy of sorts. It is shown that complete and minimal sets of unifiers may not always exist for many-sorted unification. Conditions for sort hierarchies that are equivalent for the existence of these sets with one, finitely many, or infinitely… CONTINUE READING