[CurtMonash]

I'd push back. Starship Troopers can be argued to be about political science or the like, but there's nothing about the reasoning that's inherently mathematical.

Where I'm more on the fence are about works that rely strongly on mathematical physics, like Poul Anderson's Tau Zero, or the parts of Pohl's Gateway series that most explicitly refer to black holes. I'd still say those are not "mathematical fiction", but at least it's close.