The guy beside me on the train asks me what I do.

"I'm a mathematician." I say.

I find it an awkward question. 'Professor' is a bit of an honorific, even in English, so saying I'm a professor is immodest. Sometimes I say that I teach math, but usually I'm answering this question when I'm going through customs for a conference, and then teaching math isn't really the capacity in which I am traveling. I've answered that "I do math," but the response to this is usually, "What do you mean?" So now I just say that I'm a mathematician. I used to feel that saying this was presumptuous, being a professor at a mid-level university, but I publish, so I guess that it fits.

"What kind of mathematician?" he asks.

"I do graph theory." I say, assuming by his question that he knows something about math.

"Oh!" he sounds excited, "So you're a sports mathematician?"

"Ah..." I say, unsure how to answer. "It's pure math."

"Traditional math? So you don't do competitions?"

"I did well in a couple of contests when I was young, but now its mostly just teaching and writing papers."

"I guess you could probably defend yourself in a math attack, eh?"

"Yeah," I say with a smile, "Sometimes I'm hoping for someone to come at me with a math attack, to bring back that feel, you know?"

"Yeah. I know."

"To see if I still got it, you know?"

"I think you still got it," he says.

"I think I still got it," I agree.

The conversation kind of peters off after that. I'm not really sure we've been talking about the same thing. I think about asking him what he does, but it's probably something boring. I put on my earphones and go to sleep.