Hmm, I didn't notice I was last on page 4 and discussion continued on page 5 ... I am used to edit last post instead of autoreplaying ... so look at the version on the bottom of page 4 where the authors of the original proof (HC on graph with small degree vertices) was located

BTW: Plesnik proof allows undirecting by adding vertex on outdegree 1 to indegree 1 edges. And if you want cubic graph (all vertices of degree exactly 3) you can add a square with diagonal instead of just one vertex there. So Plesnik's proof is much easier than the original one ([3]).
BTW2: An alternative ... my last step of Tron proof used "fractal corridors as edges" to make all edges (or at least these that are not forced ... (meaninig out deg 2 in deg 2)) same length (forced ones could be longer but not shorter). It would lead probably to simillar scaling as creating big chambers. My resulting map would be graph on grid with maximal degree 3.
P.S.: The book name was probably "Grafové algorítmy" ... Graph algorithms, not Graph Theory I have supposed.