## Abstract The vertices of each plane triangulation without loops and multiple edges may be colored with 11 colors so that for every two adjacent triangles [__xyz__] and [__wxy__], the vertices __x__,__y__,__w__,__z__ are colored pairwise differently.
Simultaneous diagonal flips in plane triangulations
β Scribed by Prosenjit Bose; Jurek Czyzowicz; Zhicheng Gao; Pat Morin; David R. Wood
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 468 KB
- Volume
- 54
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
Simultaneous diagonal flips in plane triangulations are investigated. It is proved that every triangulation with nββ₯β6 vertices has a simultaneous flip into a 4βconnected triangulation, and that the set of edges to be flipped can be computed in $\cal O$(n) time. It follows that every triangulation has a simultaneous flip into a Hamiltonian triangulation. This result is used to prove that for any two nβvertex triangulations, there exists a sequence of $\cal O$(log__n__) simultaneous flips to transform one into the other. Moreover, Ξ©(log n) simultaneous flips are needed for some pairs of triangulations. The total number of edges flipped in this sequence is $\cal O$(n). The maximum size of a simultaneous flip is then studied. It is proved that every triangulation has a simultaneous flip of at least ${{1}\over{3}}({n}-{2})$ edges. On the other hand, every simultaneous flip has at most n β 2 edges, and there exist triangulations with a maximum simultaneous flip of ${{6}\over{7}}({n}-{2})$ edges. Β© 2006 Wiley Periodicals, Inc. J Graph Theory 54: 307β330, 2007
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