Long cycles in subgraphs of (pseudo)random directed graphs

  • Authors:
  • Ido Ben-Eliezer;Michael Krivelevich;Benny Sudakov

  • Affiliations:
  • School of Computer Science, Raymond and Beverly Sackler, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel69978;School of Computer Science, Raymond and Beverly Sackler, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel69978;Department of Mathematics UCLA, California, Los Angeles90095

  • Venue:
  • Journal of Graph Theory
  • Year:
  • 2012

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Abstract

We study the resilience of random and pseudorandom directed graphs with respect to the property of having long directed cycles. For every 08γ81/2 we find a constant c = c(γ) such that the following holds. Let G = (V, E) be a (pseudo)random directed graph on n vertices and with at least a linear number of edges, and let G′ be a subgraph of G with (1/2 + γ)|E| edges. Then G′ contains a directed cycle of length at least (c − o(1))n. Moreover, there is a subgraph G′′of G with (1/2 + γ − o(1))|E| edges that does not contain a cycle of length at least cn. © 2011 Wiley Periodicals, Inc. J Graph Theory, © 2012 Wiley Periodicals, Inc. (Contract grant sponsors: ERC (to I. B.); USA-Israel BSF; Israel Science Foundation; Contract grant numbers: 2006322; 1063/08 (to M. K.); Contract grant sponsors: NSF grant DMS-1101185; NSF CAREER award DMS-0812005; USA-Israeli BSF.)