  Lists, multisets, and sets are well-known data structures whose usefulness is
widely recognized in various areas of Computer Science. These data structures
have been analyzed from an axiomatic point of view with a parametric approach
in (*) where the relevant unification algorithms have been developed. In this
paper we extend these results considering more general constraints including
not only equality but also membership constraints as well as their negative
counterparts.
  (*) A. Dovier, A. Policriti, and G. Rossi. A uniform axiomatic view of lists,
multisets, and sets, and the relevant unification algorithms. Fundamenta
Informaticae, 36(2/3):201--234, 1998.
