subset/2

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

[semidet]subset(+SubSet, +Set)

True if all elements of SubSet belong to Set as well. Membership test is based on memberchk/2. The complexity is |SubSet|*|Set|. A set is defined to be an unordered list without duplicates. Elements are considered duplicates if they can be unified.

See also: ord_subset/2.