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Zapiski Nauchnykh Seminarov POMI, 2014, Volume 427, Pages 74–88
(Mi znsl6044)
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On Heawood-type problem for maps with tangencies
G. V. Nenashev Department of Mathematics, Stockholm University, SE-106 91 Stockholm, Sweden
Abstract:
The class of maps on a surface of genus $g>0$ such that each point belongs to at most $k\geq3$ regions is studied. We study chromatic numbers of such maps (regions having a common point must have distinct colors) in dependence on $g$ and $k$.
In general case, upper bounds on these chromatic numbers are proved. In case $k=4$, it is proved that the problem described above is equivalent to the problem of finding the maximal chromatic number for analogues of $1$-planar graphs on a surface of genus $g$. In this case a more strong bound than in general case is obtained and a method of constructing examples which confirm accuracy of our bound is presented.
An upper bound on maximal chromatic number for analogues of $2$-planar graphs on a surface of genus $g$ is proved.
Key words and phrases:
graph embedding, map, surface, chromatic number, $1$-planar graph, topological graph.
Received: 10.11.2014
Citation:
G. V. Nenashev, “On Heawood-type problem for maps with tangencies”, Combinatorics and graph theory. Part VII, Zap. Nauchn. Sem. POMI, 427, POMI, St. Petersburg, 2014, 74–88; J. Math. Sci. (N. Y.), 212:6 (2016), 688–697
Linking options:
https://www.mathnet.ru/eng/znsl6044 https://www.mathnet.ru/eng/znsl/v427/p74
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Abstract page: | 167 | Full-text PDF : | 35 | References: | 31 |
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