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Presentation
Hankel Tournament and Special Oriented Graphs
Mathematics Faculty Proceedings, Presentations, Speeches, Lectures
  • Lei Cao, Georgian Court University
  • Richard Brualdi
Event Name/Location
8th International Conference on Matrix Analysis and Applications, Reno, Nevada, July 15-18, 2019
Presentation Date
7-1-2019
Document Type
Conference Proceeding
ORCID ID
0000-0001-7613-7191
ResearcherID
G-7341-2019
Description

A Hankel tournament T of order n (an n X n Hankel tournament matrix T = [tij]) is a tournament such that ij and edge implies (n + 1 - j) → (n + 1 - i) is also an edge (tij = tn+1-j;n+1-i) for all i and j. Hankel tournament matrices are (0,1)-matrices which are combinatorially antisymmetric about the main diagonal and symmetric about the Hankel diagonal (the antidiagonal). Locally transitive tournaments are tournaments such that the in-neighborhood and the out-neighborhood of each vertex are transitive. Tournaments form a special class of oriented graphs. The score vectors of Hankel tournaments and of locally transitive tournaments have been characterized where each score vector of a locally transitive tournament is also a score vector of a Hankel tournament. We continue investigations into Hankel tournaments and locally transitive tournaments. We investigate Hankel cycles in Hankel tournaments and show in particular that a strongly connected Hankel tournament contains a Hankel Hamilton cycle and, in fact, is Hankel "even-pancyclic" or Hankel "oddpancyclic". We show that a Hankel score vector can be achieved by a Hankel "half-transitive" tournament, extending the corresponding result for score vectors of tournaments. We also consider some results on oriented graphs and the question of attainability of prescribed degrees by oriented graphs. Finally, we extend some results on 2-tournaments to Hankel 2-tournaments.

Disciplines
Citation Information
Lei Cao and Richard Brualdi. "Hankel Tournament and Special Oriented Graphs" (2019)
Available at: http://works.bepress.com/lei-cao/13/