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Upper Domination Parameters and Edge-Critical Graphs

P. J. P. Grobler1, C. M. Mynhardt 1
1Department of Mathematics University of South Africa P. O. Box 392, UNISA 0003 SouTH AFRICA

Abstract

For \(\pi\) one of the upper domination parameters \(\beta\), \(\Gamma\), or \(IR\), we investigate graphs for which \(\pi\) decreases ( \(\pi\)-edge-critical graphs) and graphs for which \(\pi\) increases ( \(\pi^+\)-edge-critical graphs) whenever an edge is added. We find characterisations of \(\beta\)- and \(\Gamma\)-edge-critical graphs and show that a graph is \(IR\)-edge-critical if and only if it is \(\Gamma\)-edge-critical. We also exhibit a class of \(\Gamma^+\)-edge-critical graphs.