On Three-Term Linear Relations for Theta Series of Positive-Definite Binary Quadratic Forms

Abstract

In this paper, we investigate three-term linear relations among theta series of positive-definite integral binary quadratic forms. We extend Schiemann's methods to characterize all possible three-term linear relations among theta series of such forms, providing necessary and sufficient conditions for such relations to exist. To accomplish this, we develop, implement, and execute a novel extended refinement algorithm on polyhedral cones. We show that there is exactly one non-trivial three-term linear relation: it involves quadratic forms with discriminants $-3,-12,-48$, all in the same rational squareclass $-3({\mathbb{Q}}^{\times }{)}^2$.

30 pages