
Sauer, Norbert W.
Monochromatic reachability in arc-colored digraphs ★★★
Author(s): Sands; Sauer; Woodrow
Conjecture For every
, there exists an integer
such that if
is a digraph whose arcs are colored with
colors, then
has a
set which is the union of
stables sets so that every vertex has a monochromatic path to some vertex in
.








Keywords:
Monochromatic reachability or rainbow triangles ★★★
Author(s): Sands; Sauer; Woodrow
In an edge-colored digraph, we say that a subgraph is rainbow if all its edges have distinct colors, and monochromatic if all its edges have the same color.
Problem Let
be a tournament with edges colored from a set of three colors. Is it true that
must have either a rainbow directed cycle of length three or a vertex
so that every other vertex can be reached from
by a monochromatic (directed) path?




Keywords: digraph; edge-coloring; tournament
