Results 211 to 220 of about 9,271 (238)

A counterexample on contractible transformations on graphs

Discrete Mathematics, 2020
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Contractible Elements in Graphs and Matroids

Combinatorics, Probability and Computing, 2003
An edge in a 3-connected graph is termed contractible if the result upon contraction of the edge is again 3-connected. There are analogous notions more generally concerned with \(k\)-connectivity in matroids. Here it is shown that in any 3-connected graph with \(v\) vertices, there are at most \(v/5\) vertices which are not incident to contractible ...
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Contracting a Chordal Graph to a Split Graph or a Tree

2011
The problems CONTRACTIBILITY and INDUCED MINOR are to test whether a graph G contains a graph H as a contraction or as an induced minor, respectively. We show that these two problems can be solved in |VG|f(|VH|) time if G is a chordal input graph and H is a split graph or a tree.
Petr A. Golovach, Marcin Kaminski 0001, Daniël Paulusma   +2 more
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Dual Graph Contraction with LEDA

1998
Graphs are useful tools for modeling problems that occur in a variety of fields. In machine vision graph based solutions have been successfully applied to many image processing problems e.g. quad trees for image compression and region adjacency graphs for segmentation.
Walter G. Kropatsch, Mark James Burge, Souheil Ben Yacoub, N. Selmaoui   +3 more
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Contractions and hamiltonian line graphs

Journal of Graph Theory, 1988
AbstractUsing the contraction method, we find a best possible condition involving the minimum degree for a triangle‐free graph to have a spanning eulerian subgraph.
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Square contractions of graphs [PDF]

Australas. J Comb., 2006
This paper discusses the problem of contracting an arbitrary graph to a square \(C_4\). This problem is known to be NP-complete. However, it is tractable for the class of graphs whose complements have radius unequal to 2 (including graphs with infinite radius).
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Some applications of graph contractions

Journal of Graph Theory, 1977
AbstractResults in diverse areas, such as the Nielsen‐Schreier theorem on subgroups of free groups and a proof of A. T. White's conjecture on the genus of subgroups are shown to be immediate consequences of a lemma which has already proved useful in investigating topological properties and automorphism group of graphs.
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Contractible Edges in 7-Connected Graphs

Graphs and Combinatorics, 2005
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Jianji Su, Xudong Yuan
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Contraction Hierarchies on Grid Graphs

2013
Many speed-up techniques developed for accelerating the computation of shortest paths in road networks, like reach or contraction hierarchies, are based on the property that some streets are ’more important’ than others, e.g. on long routes the usage of an interstate is almost inevitable.
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Contractions of graphs with no spanning eulerian subgraphs

Combinatorica, 1988
The concept of collapsible graphs introduced by the author in J. Graph Theory 12, 29-44 (1988), is here used to study the existence of spanning Eulerian subgraphs. The following result is given: Let \(p\geq 2\) be a fixed integer, and let G be a connected graph of order n.
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