Forcing k-repetitions in degree sequences

Yair Caro, Asaf Shapira, Raphael Yuster

Research output: Contribution to journalArticlepeer-review


One of the most basic results in graph theory states that every graph with at least two vertices has two vertices with the same degree. Since there are graphs without 3 vertices of the same degree, it is natural to ask if for any fixed k, every graph G is "close" to a graph G′ with k vertices of the same degree. Our main result in this paper is that this is indeed the case. Specifically, we show that for any positive integer k, there is a constant C=C(k), so that given any graph G, one can remove from G at most C vertices and thus obtain a new graph G′ that contains at least min{k,|G|-C} vertices of the same degree. Our main tool is a multidimensional zero-sum theorem for integer sequences, which we prove using an old geometric approach of Alon and Berman.

Original languageEnglish
JournalElectronic Journal of Combinatorics
Issue number1
StatePublished - 7 Feb 2014


  • Degree sequence
  • Repetition

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Geometry and Topology
  • Discrete Mathematics and Combinatorics
  • Computational Theory and Mathematics
  • Applied Mathematics


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