English

A note on totally-omnitonal graphs

Combinatorics 2019-11-11 v1

Abstract

Let the edges of the complete graph KnK_n be coloured red or blue, and let GG be a graph with V(G)<n|V(G)| < n. Then ot(n,G) is defined to be the minimum integer, if it exists, such that any such colouring of KnK_n contains a copy of GG with rr red edges and bb blue edges for any r,b0r,b \geq 0 with r+b=e(G)r+b= e(G). If ot(n,G) exists for every sufficiently large nn, we say that GG is \emph{omnitonal}. Omnitonal graphs were introduced by Caro, Hansberg and Montejano [arXiv:1810.12375,2019]. Now let G1G_1, G2G_2 be two copies of GG with their edges coloured red or blue. If there is a colour-preserving isomorphism from G1G_1 to G2G_2 we say that the 2-colourings of GG are equivalent. Now we define tot(n,G) to be the minimum integer, if it exists, such that any such colouring of KnK_n contains all non-quivalent colourings of GG with rr red edges and bb blue edges for any r,b0r,b \geq 0 with r+b=e(G)r+b= e(G). If tot(n, G) exists for every sufficiently large nn, we say that G is \emph{totally-omnitotal}. In this note we show that the only totally-omnitonal graphs are stars or star forests namely a forest all of whose components are stars.

Keywords

Cite

@article{arxiv.1911.02800,
  title  = {A note on totally-omnitonal graphs},
  author = {Yair Caro and Josef Lauri and Christina Zarb},
  journal= {arXiv preprint arXiv:1911.02800},
  year   = {2019}
}
R2 v1 2026-06-23T12:08:18.378Z