Examples of using Pathwidth in English and their translations into Portuguese
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The pathwidth of any n-vertex cubic graph is at most n/6.
In particular the maximal graphs of pathwidth one are exactly the caterpillar trees.
The pathwidth may be computed in linear time for trees and forests.
Graph minors have a deep theory in which several important results involve pathwidth.
Observe that the pathwidth of Sk is 1, and its tree-depth is 2.
Scheffler(1992) gives a tighter upper bound of log3(2n+ 1) on the pathwidth of an n-vertex forest.
Thus, graphs of bounded pathwidth have embeddings of this type with linear volume.
The same technique, applied to a tree-decomposition of a graph, shows that, if the treewidth of an n-vertex graph G is t,then the pathwidth of G is Ot log n.
The graphs with such drawings have pathwidth that is bounded by a function of h and k.
Pathwidth, a different NP-complete optimization problem involving linear layouts of graphs.
It is NP-hard to approximate the pathwidth of a graph to within an additive constant.
Pathwidth and path-decompositions are closely analogous to treewidth and tree decompositions.
However, the best known lower bound on the pathwidth of cubic graphs is smaller, 0.082"n.
On graphs of bounded pathwidth, this approach leads to fixed-parameter tractable algorithms,parametrized by the pathwidth.
Bodlaender(1994) surveys the complexity of computing the pathwidth on various special classes of graphs.
In any planar graph, the pathwidth is at most proportional to the square root of the number of vertices.
In many cases, the properties of F and the properties of X are closely related, and the first such result of this typewas by Robertson& Seymour(1983), and relates bounded pathwidth with the existence of a forest in the family of forbidden minors.
As Bodlaender(1998) describes, pathwidth can be characterized in many equivalent ways.
The pathwidth of any graph G is equal to one less than the smallest clique number of an interval graph that contains G as a subgraph.
For earlier approximation algorithms for pathwidth, see Bodlaender et al.(1992) and Guha 2000.
Pathwidth, and graphs of bounded pathwidth, also have applications in VLSI design, graph drawing, and computational linguistics.
For 2-connected planar graphs, the pathwidth of the dual graph is less than the pathwidth of the line graph.
Pathwidth has several applications to graph drawing: The minimal graphs that have a given crossing number have pathwidth that is bounded by a function of their crossing number.
Additionally, for several special classes of graphs,such as trees, the pathwidth may be computed in polynomial time without dependence on k.
This theory, in which pathwidth is intimately connected to arbitrary minor-closed graph families, has important algorithmic applications.
Since path-decompositions are a special case of tree-decompositions, the pathwidth of any graph is greater than or equal to its treewidth.
This equivalence between pathwidth and interval thickness is closely analogous to the equivalence between treewidth and the minimum clique number(minus one) of a chordal graph of which the given graph is a subgraph.
Many problems in graph algorithms may be solved efficiently on graphs of bounded pathwidth, by using dynamic programming on a path-decomposition of the graph.
It is NP-hard to find the pathwidth of arbitrary graphs, or even to approximate it accurately.
They play a key role in the theory of graph minors: the families of graphs that are closed under graph minors anddo not include all forests may be characterized as having bounded pathwidth, and the"vortices" appearing in the general structure theory for minor-closed graph families have bounded pathwidth.