Eckhard Steffen

Edge-coloring 4- and 5-regular projective planar graphs with no Petersen-minor

An $r$-regular graph is an $r$-graph, if every odd set of vertices is connected to its complement by at least $r$ edges. We prove for $r \in \{4,5\}$, every projective planar $r$-graph with no Petersen-minor is $r$-edge colorable.