Proto-Exact Categories of Matroids over Idylls and Tropical Toric Reflexive Sheaves

Abstract: We study the category $F$-$\textbf{Mat}<em>\bullet$ of matroids over an idyll $F$. We show that $F$-$\textbf{Mat}</em>\bullet$ is a proto-exact category, a non-additive generalization of an exact category by Dyckerhoff and Kapranov. We further show that $F$-$\textbf{Mat}<em>\bullet$ is proto-abelian in the sense of Andr\'e. As an application, we establish that the category $\textbf{TRS}</em>\bullet<sup>\Sigma$ of tropical toric reflexive sheaves associated to a fan $\Sigma$, introduced by Khan and Maclagan, is also proto-exact and proto-abelian. We then investigate the stability of modular tropical toric reflexive sheaves within the framework of proto-abelian categories and reformulate Harder-Narasimhan filtrations in this setting.