Just a wee bulletin-board notice here before we begin. Next weekend, May 20th-21st-22nd, is the American Renaissance annual conference in Tennessee. I shall of course attend, but the conference schedule is not kind to Radio Derb. It begins with a reception on Friday evening, when Radio Derb is normally put to bed. I shall do my best, and there will certainly be a podcast of some description by Friday midnight — possibly including voices from the conference — but it's all a bit up in the air, and we shall see....We math geeks got a chuckle out of the story about Guido Menzio, an associate professor of economics at U. Penn., who was questioned by airline security officials because the woman in the seat next to him on his plane saw him writing strange symbols on a pad of paper.It didn't help that Dr Menzio, although of Italian heritage, has a swarthy Mediterranean appearance. His seat companion thought he might be a Muslim terrorist, so she alerted the plane crew. The plane was already on the runway, but it returned to the gate and Dr Menzio was questioned. It turned out he was just working on some differential equations.There is a long tradition of mathematicians' notes being regarded with suspicion by the laity. The French algebraist André Weil was arrested in Finland in 1939 on suspicion of being a spy on just those grounds. The Norwegian mathematician Sophus Lie was likewise arrested in Paris during the Franco-Prussian War, his math notes assumed to be top secret coded messages. I have no doubt there are other examples going all the way back to the Peloponnesian War.Here's my question, though. Were those ordinary differential equations or partial differential equations that Dr Menzio was working on? None of the news sources wanted to tell us. My guess is that they were ODEs. An economist wouldn't be smart enough to handle PDEs.