What does the symbol "⊇" mean? [closed]

Question

In the attached picture there's a symbol I don't understand. To understand additive functional dependency I need to know what the symbol means. Please advice?

It's the symbol where it says: "Suppose that X ⊇ Y and that..."

⊇ = ?

Thanks!

Recommit

Answer 1

It means "X is a superset of Y". The subset symbol is the same but flipped horizontally.

Hebetate

Answer 2

This symbol is used in set theory to say that X is a superset of Y, ie. All elements of Y are contained within X. Note that X could be equal to Y in this meaning. Without the underlining on the symbol Y would be a strict subset of X meaning they cannot be equal

Russelrussell

Answer 3

A ⊇ B -> Superset: A has the same elements as B, or more

A ⊃ B -> Proper Superset: A has B's elements and more

for example:

A ⊇ B -> {1, 2, 3} ⊇ {1, 2, 3}

A ⊃ B -> {1, 2, 3, 4} ⊃ {1, 2, 3}

Secrest