At today’s extremal combinatorics seminar at Alfréd Rényi, the speaker announced that he was going to talk about tournament coloring. I was excited, since I almost did my thesis on tournament coloring.

The speaker, András Gyárfás, started off with a handwavy definition of a tournament coloring, writing almost nothing on the board. It wasn’t quite what I’d thought, so I asked about it. He responded with a bit more handwaving and an example that failed to distinguish the definitions, whereupon other audience members started asking questions.

It turns out that there were (at least) three slightly different definitions of tournament colorings that people were used to; the talk didn’t get back on track until 15 minutes later. (The speaker doubled down on the handwavy definitions, and it took audience explanations to get back on track—the entire snafu’s a good case for rigor.)