
doi: 10.1007/bf02579312
Behzad, Chartrand and Wall conjectured that the girth of a diregular graph of ordern and outdegreer is not greater than [n /r]. This conjecture has been proved forr=2 by Behzad and forr=3 by Bermond. We prove that a digraph of ordern and halfdegree ≧4 has girth not exceeding [n / 4]. We also obtain short proofs of the above results. Our method is an application of the theory of connectivity of digraphs.
girth, Extremal problems in graph theory, Connectivity, Directed graphs (digraphs), tournaments, diregular graph
girth, Extremal problems in graph theory, Connectivity, Directed graphs (digraphs), tournaments, diregular graph
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