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Edge irregular total labellings for graphs of linear size
Authors:Stephan Brandt
Institution:a Institut für Mathematik, TU Ilmenau, Postfach 100565, D-98684 Ilmenau, Germany
b Institute of Mathematics, Faculty of Science, University of Pavol Jozef Šafarik, 040 01 Košice, Slovak Republic
Abstract:As an edge variant of the well-known irregularity strength of a graph G=(V,E) we investigate edge irregular total labellings, i.e. functions f:VE→{1,2,…,k} such that f(u)+f(uv)+f(v)≠f(u)+f(uv)+f(v) for every pair of different edges uv,uvE. The smallest possible k is the total edge irregularity strength of G. Confirming a conjecture by Ivan?o and Jendrol’ for a large class of graphs we prove that the natural lower bound View the MathML source is tight for every graph of order n, size m and maximum degree Δ with m>111000Δ. This also implies that the probability that a random graph from G(n,p(n)) satisfies the Ivan?o-Jendrol’ Conjecture tends to 1 as n for all functions p∈0,1]N. Furthermore, we prove that View the MathML source is an upper bound for every graph G of order n and size m≥3 whose edges are not all incident to a single vertex.
Keywords:Edge irregular total labelling  Total edge irregularity strength  Irregular assignment  Irregularity strength
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