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Seminar Details

The Smallest Eigenvalues of some Hamming and Johnson Graphs

  • Start Date: April 30, 2018
  • Event Start Time: 2:00 PM
  • Event End Time: 3:00 PM
  • Seminar Series: Rutgers Discrete Mathematics Seminar
  • Presenter(s): Sebastian Cioaba - University of Delaware
  • Event Location: Hill Center-Room 705
  • Presentation Type: Stand Alone Presentation
  • Abstract:

    The smallest eigenvalue of a graph is closely related to other graph parameters such as the independence number, the chromatic number or the max-cut. In this talk, I will describe some of the connections between the smallest eigenvalue and the max-cut of a graph that have motivated various researchers such as Karloff, Alon, Sudakov, Van Dam, Sotirov to investigate the smallest eigenvalue of Hamming and Johnson graphs. I will outline our proofs of a 2016 conjecture by Van Dam and Sotirov on the smallest eigenvalue of (distance-j) Hamming graphs and a 1999 conjecture by Karloff on the smallest eigenvalue of (distance-j) Johnson graphs and mention some open problems. This is joint work with Andries Brouwer, Ferdinand Ihringer and Matt McGinnis.