Please, miss, can I have another go?

No, not a theory. How about Fermat's Conjecture?

[INJ] Itself and one? NO
[Rosie1] Triangular numbers? NO
[Rosie2] Quantum mechanics? NO
[Projoy1] Square of the Hypotenuse? N- *audience explodes into applause* NO
[Projoy2] Pythagoras no greater than two? N- *audience applauds even louder, if that's even possible* NO

If this is right, the winner should really be Dujon.

[Dujon, Rosie] Shiny yellow maths? NO *audience shout "Colder!"*

Had forgotten it started with P...

[Software] Mathematician Philosophy? NO *a few claps from audience*
[Projoy] Ball manifolds? NO
[INJ] Something we've yet to hear from Colin Sell? NO *audience ooh quietly*

(I was about to suggest a platonic solid, but then realised that the whole point of them is that they don't exist in the real world.)

Oh, it's not a (mathematical) proof, is it?

Can I just say, btw, that this AVMA is (a) bloody hard and (b) very enjoyable.

[Projoy] Shaping the world? YES
(Taking the other one as a question as well) [Projoy2] Demonstrating true maths? YES
Glad you like it. I still hope that it's not taking this long because I'm answering the questions wrong. Just for another hint though; one of the questions I answered NO to earlier has got something to do with the answer, but I took the question to mean the definite article, as it were, because that's what I suspect it was intended as.

Getting a bit arcane.

I know it's wrong but I have to get it out of my head. I generally think it's a bad thing to know the first letter. Leads to all kinds of weird guesses.