Multisets

What Are Multisets

A multiset is a datatype for storing a set of objects where objects can occur more than once, but the ordering of objects does not matter. Multisets have attributes and a single domain. A multiset can be defined for both GroundDomain and UnresolvedDomain.

Attributes

Three cardinality attributes; size, minSize, maxSize. Two occurrence attributes; minOccur, maxOccur.

In the original conjure implementation, a multiset was infinite without size, maxSize, or maxOccur. In the new conjure-oxide implementation, a variable’s domain is ground if it is fully-bounded (i.e. has a minSize and maxSize).

Operators

There are four operators which are defined on functions. These are represented as Expressions in Conjure-Oxide.

• hist(m) - histogram of multi-set m
• max(m) - largest element in ordered multiset m
• min(m) - largest element in ordered multiset m
• freq(m,e) - counts occurrences of element e in multiset m