nLab
O'Nan moonshine

Contents

Idea

O’Nan moonshine concerns the existence of a graded infinite-dimensional module for the sporadic finite simple group of O’Nan, a so-called pariah group, for which the McKay-Thompson series are weight 3/2 mock modular forms. This form of moonshine relates congruences of McKay-Thompson series and the Selmer and Tate-Shafarevich groups of certain optimal elliptic curves.

References

For an informal introduction,

For a popular summary,