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Discrete Mathematics 187 (1998) 255-258. Communication ... By now, the class of median graphs is well studied and a rich structure theory is available, see e.g. ...
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DISCRETE MATHEMATICS Discrete Mathematics 187 (1998) 255-258

Communication An Euler-type formula for median graphs Sandi Klav~ara'*'l, Henry Martyn Mulder b,2, Riste Skrekovski c,3 a Department of Mathematics, PEF, University of Maribor, Korogka cesta 160, 2000 Maribor, Slovenia b Econometrisch Instituut, Erasmus Universiteit, P.O. Box 1738, 3000 DR Rotterdam, Netherlands c Department o f Mathematics, University o f Ljubljana, Jadranska 19, 1111 Ljubljana, Slovenia Received 21 January 1998; accepted 28 January 1998 Communicated by C. Benzaken

Abstract

Let G be a median graph on n vertices and m edges and let k be the number of equivalence classes of the Djokovi6's relation ~9 defined on the edge-set of G. Then 2 n - m - k ~

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