what are the symbols or notations used as related to sets

Question

symbols related to sets

Answer 1

notation from Set Theory:

1. |T| is the number of elements in set T.
2. Intersection of two sets, denoted ∩, refers to the elements that are in both sets. In the example, T∩D={d,g}.
3. Union of two sets, denoted ∪, refers to the elements that are in at least one of the two sets. In the example, T∪H={a,c,d,e,f,g}.
4. Complement (Absolute), denoted c, refers to the elements that are not in the set. In the example, Dc={a,c,e,i}.
5. Complement (Relative), denoted ∖, refers to the elements in the first set, but are not in the second set. In the example, H∖T={c,f}.

Symmetric Difference, denoted △, refers to the elements that are in at least one of the two sets, but are not in both sets. In the example, D△H={b,c,d,e