Discussiones Mathematicae Graph Theory 28(3) (2008) 419-429
doi: 10.7151/dmgt.1416

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Werner Klöckl

Chair of Applied Mathematics
Montanuniversität Leoben, 8700 Leoben, Austria
e-mail: werner.kloeckl@mu-leoben.at


The distinguishing number D(G) of a graph G is the least integer d such that G has a labeling with d colors that is not preserved by any nontrivial automorphism. The restriction to proper labelings leads to the definition of the distinguishing chromatic number χD(G) of G.

Extending these concepts to infinite graphs we prove that D(Q0) = 2 and χD(Q0) = 3, where Q0 denotes the hypercube of countable dimension. We also show that χD(Q4) = 4, thereby completing the investigation of finite hypercubes with respect to χD.

Our results extend work on finite graphs by Bogstad and Cowen on the distinguishing number and Choi, Hartke and Kaul on the distinguishing chromatic number.

Keywords: distinguishing number, distinguishing chromatic number, hypercube, weak Cartesian product.

2000 Mathematics Subject Classification: Primary: 05C25, 05C15; Secondary: 05C12.


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Received 18 October 2006
Revised 6 June 2008
Accepted 6 June 2008