Trees with distinguishing index equal distinguishing number plus one
Author(s) -
Saeid Alikhani,
Sandi Klavžar,
Florian Lehner,
Samaneh Soltani
Publication year - 2018
Publication title -
discussiones mathematicae graph theory
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.476
H-Index - 19
eISSN - 2083-5892
pISSN - 1234-3099
DOI - 10.7151/dmgt.2162
Subject(s) - mathematics , combinatorics , index (typography) , tree (set theory) , statistics , discrete mathematics , computer science , world wide web
The distinguishing number (index) D(G) (D′ (G)) of a graph G is the least integer d such that G has an vertex (edge) labeling with d labels that is preserved only by the trivial automorphism. It is known that for every graph G we have D′ (G) ≤ D(G) + 1. In this note we characterize finite trees for which this inequality is sharp. We also show that if G is a connected unicyclic graph, then D′ (G) = D(G).
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