## Abstract Every 3‐connected planar, cubic, triangle‐free graph with __n__ vertices has a bipartite subgraph with at least 29__n__/24 − 7/6 edges. The constant 29/24 improves the previously best known constant 6/5 which was considered best possible because of the graph of the dodecahedron. Example
The complexity of the matching-cut problem for planar graphs and other graph classes
✍ Scribed by Paul Bonsma
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 247 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
The Matching‐Cut problem is the problem to decide whether a graph has an edge cut that is also a matching. Previously this problem was studied under the name of the Decomposable Graph Recognition problem, and proved to be
${\cal{NP}}$‐complete when restricted to graphs with maximum degree four. In this paper it is shown that the problem remains
${\cal{NP}}$‐complete for planar graphs with maximum degree four, answering a question by Patrignani and Pizzonia. It is also shown that the problem is
${\cal{NP}}$‐complete for planar graphs with girth five. The reduction is from planar graph 3‐colorability and differs from earlier reductions. In addition, for certain graph classes polynomial time algorithms to find matching‐cuts are described. These classes include claw‐free graphs, co‐graphs, and graphs with fixed bounded tree‐width or clique‐width. © 2009 Wiley Periodicals, Inc. J Graph Theory 62: 109–126, 2009
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