On real number labelings and graph invertibility

  • Authors:
  • Jeong-Ok Choi;John Georges;David Mauro;Yan Wang

  • Affiliations:
  • Gwangju Institute of Science and Technology, Gwangju, South Korea;Department of Mathematics, Trinity College, Hartford, CT 06106, United States;Department of Mathematics, Trinity College, Hartford, CT 06106, United States;Department of Mathematics, Millsaps College, Jackson, MS 39210, United States and Department of Computer Science, Millsaps College, Jackson, MS 39210, United States

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2012

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Abstract

For non-negative real x"0 and simple graph G, @l"x"""0","1(G) is the minimum span over all labelings that assign real numbers to the vertices of G such that adjacent vertices receive labels that differ by at least x"0 and vertices at distance two receive labels that differ by at least 1. In this paper, we introduce the concept of @l-invertibility: G is @l-invertible if and only if for all positive x, @l"x","1(G)=x@l"1"x","1(G^c). We explore the conditions under which a graph is @l-invertible, and apply the results to the calculation of the function @l"x","1(G) for certain @l-invertible graphs G. We give families of @l-invertible graphs, including certain Kneser graphs, line graphs of complete multipartite graphs, and self-complementary graphs. We also derive the complete list of all @l-invertible graphs with maximum degree 3.