Given a graph
,
the tree cover number of the graph, denoted
, is
the minimum number of vertex disjoint simple trees occurring as induced subgraphs
that cover all the vertices of G. This graph parameter was introduced in
2011 as a tool for studying the maximum positive semidefinite nullity of a
graph, and little is known about it. It is conjectured that the tree cover
number of a graph is at most the maximum positive semidefinite nullity of the
graph.
In this paper, we establish bounds on the tree cover number of a graph, characterize when an
edge is required to be in some tree of a minimum tree cover, and show that the tree cover number
of the
-dimensional
hypercube is 2 for all
.
Keywords
tree cover number, hypercube, maximum nullity, minimum rank