# A “well-formed formula” (wff) video

David Weinberger has expanded his resumé with an acting gig in a great little 3-minute movie called Get Human (the video). This is for everyone who has climbed the walls while groping up (or down) a phone tree. Great film — very wickedly funny, too.

That part of the video with the phone tree options reminded me of a fiendish mathematical logics course the kids and I worked part of the way through a few years back. It was all about mastering the kind of convolutions offered by some especially non-human-userinterface-designed phone tree options: “if yes, press 1 and say no, if no press 2 and say yes,” except expressed in symbols.

Modus ponens, remember?:
1. If Statement A, then Statement B.
2. But Statement A.
3. Therefore, Statement B.

Looks like this:
1. [P –> Q]
2. P
3. Therefore, Q.

If you’re really stuck, use the contrapositive, which allows you to reverse the direction of the conditional (that’s the “if A, then B” formulation):
[P –> Q] and [[~Q] –> [~P]] are equivalent formulas: If P then Q, and If not-Q, then not-P. It’s a double negative, but it’s logical.

Well, logical as hell, maybe: the kind of logical used by automated systems, i.e., designed to drive us humans up a (phone) tree!

Note:
Definition of WFF (“well formed formula”) here. Woof-woof!