On a colorful problem by Dol'nikov concerning translates of convex bodies

Abstract

In this note we study a conjecture by Jerónimo-Castro, Magazinov and Soberón which generalized a question posed by Dol'nikov. Let $F_1,F_2,\dots ,F_n$ be families of translates of a convex compact set $K$ in the plane so that each two sets from distinct families intersect. We show that, for some $j$, ${\bigcup }_{i\ne j}{F}_i$ can be pierced by at most $4$ points. To do so, we use previous ideas from Gomez-Navarro and Roldán-Pensado together with an approximation result closely tied to the Banach-Mazur distance to the square.