Ore-type degree condition of supereulerian digraphs

A digraph D is supereulerian if D has a spanning directed eulerian subdigraph. Hong et al. proved that delta(+)(D) + delta(-)(D) >= vertical bar V(D)vertical bar - 4 implies D is supereulerian except some well-characterized digraph classes if the minimum degree is large enough. In this paper, we characterize the digraphs D which are not supereulerian under the condition d(D)(+)(u) + d(D)(-) (v) >= vertical bar V(D)vertical bar - 4 for any pair of vertices u and v with uv is not an element of A(D) without the minimum degree constraint. (C) 2016 Elsevier B.V. All rights reserved.