In this paper, we introduce a class of digraphs called \((l,m)\)-walk-regular digraphs, a common generalization of both weakly distance-regular digraphs \([1]\) and \(k\)-walk-regular digraphs \([3]\), and give several characterizations of them about their regularity properties that are related to distance and about the number of walks of given length between vertices at a given distance.
Citation
Wen Liu. On \((l,m)\)-Walk-Regular Digraphs[J], Ars Combinatoria, Volume 100. 281-287. .