Abstract
A graphG ischromatically k-connected if every vertex cutset induces a subgraph with chromatic number at leastk. This concept arose in some work, involving the third author, on Ramsey Theory. (For the reference, see the text.) Here we begin the study of chromatic connectivity for its own sake. We show thatG is chromaticallyk-connected iff every homomorphic image of it isk-connected. IfG has no triangles then it is at most chromatically 1-connected, but we prove that the Kneser graphs provide examples ofK 4-free graphs with arbitrarily large chromatic connectivity. We also verify thatK 4-free planar graphs are at most chromatically 2-connected.
Similar content being viewed by others
References
Lovász, L.: Kneser's conjecture, chromatic number, and homotopy. J. Comb. Theory (A)25, 319–324 (1978)
Nešetřil, J., V. Rödl.: Partition theory and its applications. In: Surveys in Combinatorics, edited by Bollobás B. pp. 96–156. Cambridge: Cambridge University Press 1979
Saaty, T., Kainen, P.: The Four Colour Problem. New York: McGraw-Hill 1977
Author information
Authors and Affiliations
Additional information
This work was supported by grants from NSERC of Canada.
Rights and permissions
About this article
Cite this article
Godsil, C.D., Nowakowski, R. & Nešetřil, J. The chromatic connectivity of graphs. Graphs and Combinatorics 4, 229–233 (1988). https://doi.org/10.1007/BF01864163
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01864163