An Improved Planar Graph Product Structure Theorem

Dujmovic, Joret, Micek, Morin, Ueckerdt and Wood [J. ACM 2020] proved that for every planar graph G there is a graph H with treewidth at most 8 and a path P such that G subset of H boxed times P. We improve this result by replacing "treewidth at most 8" by "simple treewidth at most 6".