And the way you do that is, essentially, you can almost imagine that this is kind of a less than or equal sign. And then you kind of cross out the equal part of the less than or equal sign. So this means a strict subset, which means everything that is in B is a member of A, but everything that's in A is not a member of B. So let me write this. This is B. B is a strict or proper subset. So for example, we can write that A is a subset of A.