Linear Spaces over Perfect Idylls

Abstract

We construct a category of vector space-like objects called linear spaces over perfect idylls $k$ (an algebraic structure generalizing fields and hyperfields), which is a specialization of modules over $k$. Previous authors have noted that naive linear algebra in the product $k^n$ fails because linear independence does not satisfy matroid independence axioms. We give a sufficient axiom so that linear independence in $k$-linear spaces does satisfy matroid independence axioms. We also examine basic categorical properties of $k$-linear spaces. In particular, the category of $k$-linear spaces has no products, explaining the failure of naive linear algebra in $k^n$. Furthermore, we explore the categorical relationship between linear spaces over a perfect idyll, ordinary matroids, and matroids over a perfect idyll, connecting the existing theories of matroids and modules.