That mathematical subplot does make-up about half of this novel, and hence it certainly is an example of mathematical fiction. The other half is a romance between Meg and Isaac, the young man who used to work as a handyman for her grandmother. Despite an obvious attraction for each other, they did nothing more than touch hands once in their youth. But, meeting again after Meg's failed talk on The Impossible Theorem, they begin a torrid romance...despite the fact that Isaac is wanted for murder!

I had a tough time deciding whether to label this book as being in the "Romance" genre. It certainly bears some similarity to the books in the standard "bodice ripping" novels, including but not limited to the extremely predictable outcome to all of the plot lines (IMHO). In other ways it does not conform to my stereotypes of "romance fiction". I have decided to give it that tag, but would appreciate it if any true fans of that genre could let me know whether they believe I have miscategorized it.

Anyway, let me say a bit more about the math:

• The mathematical result that is the MacGuffin of the book is "Frieholdt's Conjecture". There is no real mathematical result by that name, but this one clearly is loosely based on the Navier-Stokes Problem of proving the regularity of solutions to that fluid flow model under certain conditions. It is fictionalized here not only by the change in name but also through the implication that its solution would help solve the climate crisis by allowing for the design of more efficient engines and vehicles.
• The portrayal of academic math here is pretty good. By that, I mean that it seems more realistic to me than many other works of fiction in which mathematicians behave in ways wholly unlike anything I have seen in my real experiences. On the other hand, there were enough flubs in the way things were said and in the few mathematical details presented that I was always sure that the author has no personal experience with advanced mathematics or life as a mathematician. The author admits this in the acknowledgements when she says "Serious mathematicians will look at the mathematical language in this book and see that most, if not all of it, is complete nonsense. I, of course, do not understand the tiniest fraction of how that level of math really works. What I was exploring as I wrote this story and the character was the mind and heart of a researcher." And, I think she did a pretty good job of achieving that goal!
• There is no doubt that there has been and continues to be sexism in professional mathematics. The sexism of the distant past in the book is represented by the (fictional) mathematician Bonnie Fenty who had to pretend to be male in order to publish her work. I think it would have been better if Read has referenced some real female mathematician, but the story of Fenty rings true since I can think of real mathematicians with similar stories. The sexism faced by the contemporary mathematicians in the story -- which apparently takes place sometime after 2020 -- however struck me as exaggerated. As I am a male mathematician, it is certainly possible that I am blind to the current situation. The author did consult with mathematician Sally Collins and her experience may well be different than mine. In any case, let me just state that there are dangers both in exaggerating the amount of sexism faced by female mathematicians today as well as in downplaying it.
• The cover of the paperback edition I own features some mathematical notation in the background and a cartoonish picture of Meg (presumably) smirking and looking to the side while holding her glasses in her hand. Moreover, the title is typeset in a way that emphasizes the pun of the title. It says "PRINCIPLES OF (E)MOTION".

Meg's father announces publicly that he will be presenting his proof of "the Impossible Theorem" at an upcoming lecture. He seems to be suggesting that his daughter Meg played a tiny part in proving it, but that it is primarily his. Since her reputation suffered when she quit her academic job, it is easy for others to believe that he is just sharing some credit with his "mental ill" daughter as a kindness to her.

Meanwhile, Meg is racing to reproduce her proof before he does. A couple of thoughts about that:

• I wasn't sure why she was racing to reproduce the proof. She acted as if she could prove it was hers simply by having another copy, but I don't see how that would convince anyone.
• She was having a lot of trouble rewriting the proof that she was going to present as a lecture not long ago. To me, that seemed unlikely...unless, the proof had never been valid in the first place. And, indeed, that turns out to be the case.

Again, however, that does not seem to me as if it would convince anyone that he had stolen the invalid proof from her. I wish I believed it, because it is supposed to be the happy ending of the mathematical subplot. We are supposed to feel that justice was done as her father's misdeed has been revealed, but I think that could have been better achieved in some other way.

Anyway, as mathematical fiction romance novels go, this one is really quite good. I recommend it to anyone who likes that combination of genres.