Quadratically Enriched Tropical Intersections

Using tropical geometry one can translate problems in enumerative geometry to combinatorial problems. Thus tropical geometry is a powerful tool in enumerative geometry over the complex and real numbers. Results from ${\mathbb{A}}^1$-homotopy theory allow to enrich classical enumerative geometry questions and get answers over an arbitrary field. In the resulting area, ${\mathbb{A}}^1$-enumerative geometry, the answer to these questions lives in the Grothendieck-Witt ring of the base field $k$. In this paper, we use tropical methods in this enriched set up by showing Bézout’s theorem and a generalization, namely the Bernstein-Kushnirenko theorem, for tropical hypersurfaces enriched in $\mathrm{GW}(k)$.