3 research outputs found
Minimum Eccentricity Shortest Path Problem with Respect to Structural Parameters
The Minimum Eccentricity Shortest Path Problem consists in finding a shortest
path with minimum eccentricity in a given undirected graph. The problem is
known to be NP-complete and W[2]-hard with respect to the desired eccentricity.
We present fpt algorithms for the problem parameterized by the modular width,
distance to cluster graph, the combination of distance to disjoint paths with
the desired eccentricity, and maximum leaf number
On computing tree and path decompositions with metric constraints on the bags
We here investigate on the complexity of computing the \emph{tree-length} and
the \emph{tree-breadth} of any graph , that are respectively the best
possible upper-bounds on the diameter and the radius of the bags in a tree
decomposition of . \emph{Path-length} and \emph{path-breadth} are similarly
defined and studied for path decompositions. So far, it was already known that
tree-length is NP-hard to compute. We here prove it is also the case for
tree-breadth, path-length and path-breadth. Furthermore, we provide a more
detailed analysis on the complexity of computing the tree-breadth. In
particular, we show that graphs with tree-breadth one are in some sense the
hardest instances for the problem of computing the tree-breadth. We give new
properties of graphs with tree-breadth one. Then we use these properties in
order to recognize in polynomial-time all graphs with tree-breadth one that are
planar or bipartite graphs. On the way, we relate tree-breadth with the notion
of \emph{-good} tree decompositions (for ), that have been introduced
in former work for routing. As a byproduct of the above relation, we prove that
deciding on the existence of a -good tree decomposition is NP-complete (even
if ). All this answers open questions from the literature.Comment: 50 pages, 39 figure