A proper subset is denoted using the symbol and is typically used in an expression like this:
In plain language, this means that the set is a proper subset of the set . Sometimes, this is also referred to as strict subset notation.
The subset operator is denoted using a U shapes symbol rotated ninety degrees to the righ with a horizontal line underneath.
A proper superset is denoted by the superset symbol which looks like a U rotated ninety degrees to the left.
The superset operator in set theory is denoted using the superset symbol which looks like a U turned ninety degrees counter clockwise with a horizontal line underneath.