Abstract
Recently, Pawlik et al. have shown that triangle-free intersection graphs of line segments in the plane can have arbitrarily large chromatic number. Specifically, they construct triangle-free segment intersection graphs with chromatic number Θ(loglogn). Essentially the same construction produces Θ(loglogn)-chromatic triangle-free intersection graphs of a variety of other geometric shapes—those belonging to any class of compact arc-connected subsets of ℝ2 closed under horizontal scaling, vertical scaling, and translation, except for axis-aligned rectangles. We show that this construction is asymptotically optimal for the class of rectangular frames (boundaries of axis-aligned rectangles). Namely, we prove that triangle-free intersection graphs of rectangular frames in the plane have chromatic number O(loglogn), improving on the previous bound of O(logn). To this end, we exploit a relationship between off-line coloring of rectangular frame intersection graphs and on-line coloring of interval overlap graphs. Our coloring method decomposes the graph into a bounded number of subgraphs with a tree-like structure that “encodes” strategies of the adversary in the on-line coloring problem, and colors these subgraphs with O(loglogn) colors using a combination of techniques from on-line algorithms (first-fit) and data structure design (heavy-light decomposition).
T. Krawczyk and A. Pawlik were supported and B. Walczak was partially supported by the MNiSW grant no. 884/N-ESF-EuroGIGA/10/2011/0 as part of ESF EuroGIGA project GraDR. B. Walczak was partially supported by Swiss National Science Foundation Grant no. 200020-144531.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Zykov, A.A.: On some properties of linear complexes. Mat. Sb. (N.S.) 24(66)(2), 163–188 (1949) (in Russian)
Mycielski, J.: Sur le coloriage des graphes. Colloq. Math. 3, 161–162 (1955)
Kim, J.H.: The Ramsey number R(3,t) has order of magnitude t 2/logt. Random Struct. Algor. 7(3), 173–208 (1995)
Ajtai, M., Komlós, J., Szemerédi, E.: A note on Ramsey numbers. J. Combin. Theory Ser. A 29(3), 354–360 (1980)
Asplund, E., Grünbaum, B.: On a colouring problem. Math. Scand. 8, 181–188 (1960)
Gyárfás, A.: On the chromatic number of multiple interval graphs and overlap graphs. Discrete Math. 55(2), 161–166 (1985)
Gyárfás, A.: Corrigendum: On the chromatic number of multiple interval graphs and overlap graphs. Discrete Math. 62(3), 333 (1986)
Burling, J.P.: On coloring problems of families of prototypes. PhD thesis, University of Colorado, Boulder (1965)
Pawlik, A., Kozik, J., Krawczyk, T., Lasoń, M., Micek, P., Trotter, W.T., Walczak, B.: Triangle-free intersection graphs of line segments with large chromatic number. arXiv:1209.1595 (submitted)
Pawlik, A., Kozik, J., Krawczyk, T., Lasoń, M., Micek, P., Trotter, W.T., Walczak, B.: Triangle-free geometric intersection graphs with large chromatic number. Discrete Comput. Geom. 50(3), 714–726 (2013)
McGuinness, S.: Colouring arcwise connected sets in the plane I. Graph. Combin. 16(4), 429–439 (2000)
Suk, A.: Coloring intersection graphs of x-monotone curves in the plane. To appear in Combinatorica, arXiv:1201.0887
Fox, J., Pach, J.: Coloring K k -free intersection graphs of geometric objects in the plane. European J. Combin. 33(5), 853–866 (2012)
Fox, J., Pach, J.: Applications of a new separator theorem for string graphs. To appear in Combin. Prob. Comput., arXiv:1302.7228
Sleator, D.D., Tarjan, R.E.: A data structure for dynamic trees. J. Comput. System Sci. 26(3), 362–391 (1983)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2013 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Krawczyk, T., Pawlik, A., Walczak, B. (2013). Coloring Triangle-Free Rectangular Frame Intersection Graphs with O(loglogn) Colors. In: Brandstädt, A., Jansen, K., Reischuk, R. (eds) Graph-Theoretic Concepts in Computer Science. WG 2013. Lecture Notes in Computer Science, vol 8165. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-45043-3_29
Download citation
DOI: https://doi.org/10.1007/978-3-642-45043-3_29
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-45042-6
Online ISBN: 978-3-642-45043-3
eBook Packages: Computer ScienceComputer Science (R0)