Radial Digraphs
Radii and centers in iterated line digraphs
We show that the out-radius and the radius grow linearly, or "almost" linearly, in iterated line digraphs. Further, iterated line digraphs with a prescribed out-center, or a center, are constructed. It is shown that not every line digraph is admissible as an out-center of line digraph.
Rainbow Connectivity of Cacti and of Some Infinite Digraphs
An arc-coloured digraph D = (V,A) is said to be rainbow connected if for every pair {u, v} ⊆ V there is a directed uv-path all whose arcs have different colours and a directed vu-path all whose arcs have different colours. The minimum number of colours required to make the digraph D rainbow connected is called the rainbow connection number of D, denoted rc⃗ (D). A cactus is a digraph where each arc belongs to exactly one directed cycle. In this paper we give sharp upper and lower bounds for the...
Random sampling of labeled tournaments.
Randomly Eulerian digraphs
Reachability relations and the structure of transitive digraphs.
Reconstructing a Graph from the Incidence Relation on its Edge Set
Reconstruction of complete interval tournaments. II.
Réductions de graphes et systèmes de Church-Rosser
Regular elements of the semigroup of all binary relations.
Remark about a construction of some tournaments points of certain projective planes
Remark to a problem on 0-1 matrices
Remarks on dimensions of graphs
Remarks on flows in network with short paths
Representation of the finite directed acyclic graph
Resolvable Mendelsohn designs with block size 4.
Restricted Eulerian circuits in directed graphs