Примеры использования Pathwidth на Английском языке и их переводы на Русский язык
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The pathwidth of any n-vertex cubic graph is at most n/6.
The graphs with such drawings have pathwidth that is bounded by a function of h and k.
The"complexity" of a vortex is limited by a parameter called its depth,closely related to pathwidth.
However, the pathwidth may be computed in linear time for trees and forests.
In the other direction, if X contains an n-vertex forest,then the X-minor-free graphs have pathwidth at most n- 2.
Therefore, the graphs of pathwidth at most p can be characterized by a set Xp of excluded minors.
In this terminology, a 1-caterpillar is the same thingas a caterpillar tree, and k-caterpillars are the edge-maximal graphs with pathwidth k.
Pathwidth and path-decompositions are closely analogous to treewidth and tree decompositions.
However, unlike the Strahler number, the pathwidth is defined only for the whole graph, and not separately for each node in the graph.
In one direction, this result is straightforward to prove: if X does not include at least one forest,then the X-minor-free graphs do not have bounded pathwidth.
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.
The ability to handle graphs with cycles andnot just trees gives pathwidth extra versatility compared to the Strahler number.
There exist cubic graphs with pathwidth 0.082n, but it is not known how to reduce this gap between this lower bound and the n/6 upper bound.
Since path-decompositions are a special case of tree-decompositions, the pathwidth of any graph is greater than or equal to its treewidth.
It remains open whether the pathwidth of a planar graph and its dual are always within a constant factor of each other in the remaining cases.
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.
As a consequence, the pathwidth of a graph is always at least as large as its treewidth, but it can only be larger by a logarithmic factor.
Many problems in graph algorithms may be solved efficiently on graphs of low pathwidth, by using dynamic programming on a path-decomposition of the graph.
This theory, in which pathwidth is intimately connected to arbitrary minor-closed graph families, has important algorithmic applications.
Planar graphs that can be partitioned into nested cycles, 2-outerplanar graphs andplanar graphs of bounded pathwidth, have universal point sets of nearly-linear size.
Then, a minor-closed family F has bounded pathwidth if and only if the set X of forbidden minors for F includes at least one forest.
Pathwidth is also known as interval thickness(one less than the maximum clique size in an interval supergraph of G), vertex separation number, or node searching number.
This property parallels similar relations between pathwidth and interval graphs, and between treewidth and chordal graphs.
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.
But a perfect binary tree with 2k+ 1 levels has pathwidth k, so in this case the X-minor-free-graphs have unbounded pathwidth.
The pathwidth of a graph has a very similar definition to treewidth via tree decompositions, but is restricted to tree decompositions in which the underlying tree of the decomposition is a path graph.
Specifically, define a family F of graphs to have bounded pathwidth if there exists a constant p such that every graph in F has pathwidth at most pp.
A tree decomposition in which the underlying tree is a path graph is called a path decomposition, andthe width parameter derived from these special types of tree decompositions is known as pathwidth.
The same dynamic programming method also can be applied to graphs with unbounded pathwidth, leading to algorithms that solve unparametrized graph problems in exponential time.
The pathwidth of an arbitrary undirected graph G may be defined as the smallest number w such that there exists an interval graph H containing G as a subgraph, with the largest clique in H having w+ 1 vertices.