Connectivity of orientations of 3-edge-connected graphs

We attempt to generalize a theorem of Nash-Williams stating that graph has k-arc-connected orientation if and only it is 2k-edge-connected. In strongly connected digraph we call an arc deletable its deletion leaves digraph. Given 3-edge-connected G, define Frank number f(G) be the minimum k such there exist orientations G with property every edge becomes in at least one these orientations. are interested finding good upper bound for number. prove f(G)?7 graph. On other hand, show 3 attained by Petersen Further, better bounds more restricted classes graphs establish connection Berge–Fulkerson conjecture. also deciding whether all edges given subset can become NP-complete.