I could not quite understand this short story or its purpose. A mathematics professor has assigned some problem to students and during his student-visit hours (presumably), a female student shows up to whom he explains how the routine solution, which has been giving her some problem, may be thought of in a different fashion. The girl is not terribly convinced. After she leaves, the professor explains the same thing to another student who walks in, though now, the professor has some doubt about this second way of looking at the solution. By the time the second student leaves, the professor has erased the second solution.
There are references to mathematical jargon and coordinate axes in the story, and a weird thought the professor has that the girl’s dress looks like it has “stakes driven through the foci of a parabola”. I suspect he meant “an ellipse”, since a parabola has one focus (not “foci”), is an open-ended curve not suitable for a dress, and an ellipse conforms more to the shape of a frock’s hem. But then, all of this is just pointless, isn’t it? ...