Explicit linear pfaffian representations of plane curves up to degree 5

Abstract

Let R be a commutative ring with 1. We prove that every homogeneous polynomial f(x_0,x_1,x_2) in R[x_0,x_1,x_2] up to degree 5 admits a linear Pfaffian R-representation. We believe that conceptually we give the shortest self-contained proof possible: we exhibit explicitly such a representation. In this sense, we generalize (up to degree 5) a result due to A. Beauville about the existence of Pfaffian representations for any smooth plane curve of any degree.