<Dl> <Dd> Formally: </Dd> <Dd> A ⊆ B ⇔ A ∩ B = A . (\ displaystyle A \ subseteq B \ Leftrightarrow A \ cap B = A .) </Dd> </Dl> <Dd> A ⊆ B ⇔ A ∩ B = A . (\ displaystyle A \ subseteq B \ Leftrightarrow A \ cap B = A .) </Dd> <P> Some authors use the symbols ⊂ and ⊃ to indicate subset and superset respectively; that is, with the same meaning and instead of the symbols, ⊆ and ⊇ . So for example, for these authors, it is true of every set A that A ⊂ A . </P> <P> Other authors prefer to use the symbols ⊂ and ⊃ to indicate proper subset and proper superset respectively; that is, with the same meaning and instead of the symbols, ⊊ and ⊋ . This usage makes ⊆ and ⊂ analogous to the inequality symbols ≤ and <. For example, if x ≤ y then x may or may not equal y, but if x <y, then x definitely does not equal y, and is less than y . Similarly, using the convention that ⊂ is proper subset, if A ⊆ B, then A may or may not equal B, but if A ⊂ B, then A definitely does not equal B . </P>

What is the symbol of subset in math