Maths, Mathematics, Discrete Mathematics, Sets.
(denoted T ⊇ S). For instance: {1, 2} ⊆ {1, 2, 3} A set S is a proper subset of a set T (denoted S ⊂ T) if S ⊆ T and S ≠ T. That is, every element of S is an element of T and there is at least one element in T that is not an element of S. In this case, T is a proper superset of S (denoted T ⊃ S).