An arc in a tournament T with n ≥ 3 vertices is called pancyclic if it belongs to a cycle of length l for all 3 ≤ l ≤ n. We call a vertex u of T an out-arc pancyclic vertex of T if each out-arc of u is pancyclic in T . Yao, Guo and Zhang [Discrete Appl. Math. 99 (2000), 245–249] proved that every strong tournament contains at least one out-arc pancyclic vertex, and they gave an infinite class o...

An arc in a tournament T with n ≥ 3 vertices is called k-pancyclic, if it belongs to a cycle of length l for all k ≤ l ≤ n. In this paper, the result that each s-strong (s ≥ 3) tournament T contains at least s + 2 out-arc 5-pancyclic vertices is obtained. Furthermore, our proof yields a polynomial algorithm to find s + 2 out-arc 5-pancyclic vertices of T .

A digraph T is called a local tournament if for every vertex x of T, the set of in-neighbors as well as the set of out-neighbors of x induce tournaments. We give characterizations of generalized arc-pancyclic and strongly path-panconnected local tournaments, respectively. Our results generalize those due to Bu and Zhang (1996) about arc-pancyclic local tournaments and about strongly arc-pancycl...

A tournament is a digraph, where there is precisely one arc between every pair of distinct vertices. An arc is pancyclic in a digraph D, if it belongs to a cycle of length l, for all 3 <= l <= |V (D)|. Let p(D) denote the number of pancyclic arcs in a digraph D and let h(D) denote the maximum number of pancyclic arcs belonging to the same Hamilton cycle of D. Note that p(D) >= h(D). Moon showed...

An arc in a tournament T with n 3 vertices is called k-pancyclic, if it belongs to a cycle of length for all k n. In this paper, we show that each s-strong tournament with s 3 contains at least s + 1 vertices whose out-arcs are 4-pancyclic. © 2006 Elsevier B.V. All rights reserved.

Let $T$ be a non-trivial tournament. An arc is emph{$t$-pancyclic} in $T$, if it is contained in a cycle of length $ell$ for every $tleq ell leq |V(T)|$. Let $p^t(T)$ denote the number of $t$-pancyclic arcs in $T$ and $h^t(T)$ the maximum number of $t$-pancyclic arcs contained in the same Hamiltonian cycle of $T$. Moon ({em J. Combin. Inform. System Sci.}, {bf 19} (1994), 207-214) showed that $...

Thomassen (J. Combin. Theory Ser. B 28, 1980, 142–163) proved that every strong tournament contains a vertex x such that each arc going out from x is contained in a Hamiltonian cycle. In this paper, we extend the result of Thomassen and prove that a strong tournament contains a vertex x such that every arc going out from x is pancyclic, and our proof yields a polynomial algorithm to nd such a v...

A digraph D=(V(D),A(D)) of order n≥3 is pancyclic, whenever D contains a directed cycle length k for each k∈{3,…,n}; and vertex-pancyclic iff, vertex v∈V(D) k∈{3,…,n}, passing through v. Let D1, D2, …, Dk be collection pairwise disjoint digraphs. The generalized sum (g.s.) Dk, denoted by ⊕i=1kDi or D1⊕D2⊕⋯⊕Dk, the set all digraphs satisfying: (i) V(D)=⋃i=1kV(Di), (ii) D〈V(Di)〉≅Di i=1,2,…,k, (ii...

A tournament is an orientation of a complete graph and a multipartite or c-partite tournament is an orientation of a complete c-partite graph. If D is a digraph, then let d + (x) be the outdgree and d ? (x) the indegree of the vertex x in D. The minimum (maximum) out-degree and the minimum (maximum) indegree of D are denoted by + ((+) and ? ((?), respectively. In addition, we deene = minf + ; ?...

Let D be an oriented graph of order n 9, minimum degree n ? 2, such for choice of distinct vertices x and y, either xy 2 E(D) or d + (x)+d ? (y) n?3. Song (J. Graph Theory 18 (1994), 461{468) proved that D is pancyclic. In this note, we give a short proof, based on Song's result, that D is in fact vertex pancyclic. This also generalizes a result of Jackson (J. Graph Theory 5 (1981), 147{157) fo...