Quotients of A-hypergeometric systems
Laura Matusevich, Texas A&M

Abstract: A-hypergeometric systems of differential equations were introduced by Gelfand, Graev, Kapranov and Zelevinsky in the late 1980s. One of their main features is that they are equivariant under a torus action, and most results proved in this context take full advantage of this fact. It is known that any of the classical hypergeometric functions (Gauss, Appell, Horn, Lauricella, etc) can be made A- hypergeometric by a monomial change of variables, but the relationship between the corresponding differential equations remained unclear. I will report on joint work (in progress) with Christine Berkesch, where we interpret classical hypergeometric equations as quotients of A-hypergeometric systems. This allows us to characterize which (classical) hypergeometric systems are holonomic, have regular singularities, or have irreducible monodromy representation.