What does A\B mean in set theory?

[physicsuser]

Hi, stupid question but what does A\B mean?

 

[chroot]

You might want to provide some context to the question. Otherwise, it's meaningless.

It might mean "A divided by B" or "A given B" or any number of other things.

- Warren

 

[Galileo]

If A and B are sets:
$$A\setminus B=\{x\in A | x\notin B\}$$

Sometimes also written as A-B.

 

[physicsuser]

A and B are sets...

X is improper subset of A\B

http://en.wikipedia.org/wiki/Marriage_theorem#Graph_theory
they have S\T