2 problems

Let $N$ range over the 24 Niemeier lattices and let $\Phi(N)$ be the associated set of Conway or umbral twining functions. Realization conjecture. For every element…

Let $\mathcal{T}(\Pi)$ be a $K3$ nonlinear sigma model with symmetry group $G$, let $\Gamma_G$ be its co-invariant lattice, and let $\Phi(N)$ denote the corresponding set of Conway…