A Self-Dual Integral Form of the Moonshine Module

We construct a self-dual integral form of the moonshine vertex operator algebra, and show that it has symmetries given by the Fischer-Griess monster simple group. The existence of this form resolves the last remaining open assumption in the proof of the modular moonshine conjecture by Borcherds and Ryba. As a corollary, we find that Griess’s original 196884-dimensional representation of the monster admits a positive-definite self-dual integral form with monster symmetry.