Model theory
What is model theory? I tried to think of a succinct yet poignant explanation of it, or failing that something crudely funny. Having failed on both accounts I turned to the nearest model theory textbook a-sitting on my desk.
David Marker's very useful Model theory: an introduction offers the following sage advice.
Model theory is a branch of mathematical logic where we study mathematical structures by considering first-order sentences true in those structures and the sets definable by first-order formulas.
So there you have it. Astonishingly, no model theory texts start with rip-snortingly funny one-liners, so here's a joke involving a model theorist courtesy of Richard Carr.
A new PhD student in algebra gets a temporary position at a University for a year. He bumps into one of the faculty and, having the cockiness and arrogance of youth, says to him, "I have heard it said that all logicians go insane. Why then did you decide to study Model Theory?"
"My dear Doctor, very few logicians go insane but the entire algebra faculty is seeing the psychiatrist," replied the logician.
Thusly tempered, the young man replies uncertainly, "The entire faculty?"
"Yes, they're all in group therapy."
Sorry.
