Abstract
In this paper, we consider the following firefighter problem on a finite graph G = (V, E). Suppose that a fire breaks out at a given vertex \({v \in V}\) . In each subsequent time unit, a firefighter protects one vertex which is not yet on fire, and then the fire spreads to all unprotected neighbours of the vertices on fire. The objective of the firefighter is to save as many vertices as possible. The surviving rate \({\rho(G)}\) of G is defined as the expected percentage of vertices that can be saved when a fire breaks out at a random vertex of G. Let ε > 0. We show that any graph G on n vertices with at most \({(\frac {15}{11} - \varepsilon)n}\) edges can be well protected, that is, \({\rho(G) > \frac {\varepsilon}{60} > 0}\) . Moreover, a construction of a random graph is proposed to show that the constant \({\frac {15}{11}}\) cannot be improved.
Similar content being viewed by others
References
Alon N., Chung F.R.K.: Explicit construction of linear sized tolerant networks. Discrete Math. 72, 15–19 (1988)
Alon N., Milman V.D.: \({\lambda_1}\) , isoperimetric inequalities for graphs and superconcentrators. J. Combin. Theory B 38, 73–88 (1985)
Alon, N., Spencer, J.H.: The Probabilistic Method. Wiley, New York, 1992 (2nd edn, 2000)
Bollobás B.: A probabilistic proof of an asymptotic formula for the number of labelled regular graphs. Eur. J. Combin. 1, 311–316 (1980)
Bollobás B.: Random Graphs. Academic Press, London (1985)
Cai L., Cheng Y., Verbin E., Zhou Y.: Surviving rates of graphs with bounded treewidth for the firefighter problem. SIAM J. Discrete Math. 24(4), 1322–1335 (2010)
Cai L., Wang W.: The surviving rate of a graph. SIAM J. Discrete Math. 23(4), 1814–1826 (2009)
Finbow S., Hartnell B., Li Q., Schmeisser K.: On minimizing the effects of fire or a virus on a network. Papers in honour of Ernest J. Cockayne. J. Combin. Math. Combin. Comput. 33, 311–322 (2000)
Finbow S., King A., MacGillivray G., Rizzi R.: The firefighter problem for graphs of maximum degree three. Discrete Math. 307, 2094–2105 (2007)
Finbow S., MacGillivray G.: The firefighter problem: a survey of results, directions and questions. Aust. J. Combin. 43, 57–77 (2009)
Finbow S., Wang P., Wang W.: The surviving rate of an infected network. Theor. Comput. Sci. 411, 3651–3660 (2010)
Friedman, J.: A proof of Alon’s second eigenvalue conjecture. Mem. A.M.S. (accepted)
Hartnell, B.: Firefighter! An application of domination. In: Presentation at the 25th Manitoba Conference on Combinatorial Mathematics and Computing. University of Manitoba, Winnipeg, Canada (1995)
Hartnell B., Li Q.: Firefighting on trees: how bad is the greedy algorithm? Congr. Numer. 145, 187–192 (2000)
Hoory S., Linial N., Wigderson A.: Expander graphs and their applications. Bull. Am. Math. Soc. (N.S.) 43(4), 439–561 (2006)
Prałat, P.: Sparse graphs are not flammable. Preprint
Wormald, N.C.: Models of random regular graphs. In: Lamb, J.D., Preece, D.A. (eds.) Surveys in Combinatorics. London Mathematical Society Lecture Note Series, vol. 276, pp. 239–298. Cambridge University Press, Cambridge (1999)
Author information
Authors and Affiliations
Corresponding author
Additional information
The author gratefully acknowledges support from NSERC, MPrime, and Ryerson University.
Rights and permissions
About this article
Cite this article
Prałat, P. Graphs with Average Degree Smaller Than \({\frac {30}{11}}\) Burn Slowly. Graphs and Combinatorics 30, 455–470 (2014). https://doi.org/10.1007/s00373-012-1265-9
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00373-012-1265-9