This doesn’t make much sense in conventional algebra. Because F is the class of all female cats, and (1 – F) is the class of all cats that aren’t female, the union of these two classes is 1: F + (1 – F) = 1 and the intersection of the two classes is 0: F x (1 – F) = 0 Historically, this formulation represents an important concept in logic: It’s called the Law of Contradiction and indicates that something can’t be both itself and the opposite of itself. Where Boolean algebra really looks different from conventional algebra is in a statement like this:
