Facial packing edge-coloring of plane graphs

A facialk-packing edge-coloring of a plane graph G is a coloring of its edges with colors 1,…,k such that every facial trail containing two edges with the same color i has length at least i+2. The smallest integer k such that G admits a facial k-packing edge-coloring is denoted by pf′(G). We prove that pf′(G)≤20 for every 3-edge-connected plane graph G.