Do all longest paths share a common point? (Gallai 1966)
A few years later, Walther produced a counterexample on 25 vertices (a). The simplest counterexample was found by both Walther and Zamfirescu independently and has 12 vertices (b).
I found this examples in numerous study, but i couldn't find a vertex that does not appear in all longest paths.
Could you explain how should i see these graphs? Where are paths which intersection are empty?