union/3

Availability::- use_module(library(lists)).(can be autoloaded)

[det]union(+Set1, +Set2, -Set3)

True if Set3 unifies with the union of the lists Set1 and Set2. The complexity of this predicate is |Set1|*|Set2|. A set is defined to be an unordered list without duplicates. Elements are considered duplicates if they can be unified.

See also: ord_union/3