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MATHEMATICA BOHEMICA, Vol. 120, No. 2, pp. 203-207, 1995
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Note on the relation between radius and diameter of a graph

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Ferdinand Gliviak, Peter Kys

F. Gliviak, Faculty of Mathematics and Physics, KNOM, Comenius University, 842 15 Bratislava, Mlynska dolina, Slovakia, e-mail: gliviak@fmph.uniba.sk; P. Kys, Faculty of Mathematics and Physics, KPG, Comenius University, 842 15 Bratislava, Mlynska dolina, Slovakia, e-mail: kys@mff.uniba.sk

**Abstract:** The known relation between the standard radius and diameter holds for graphs, but not for digraphs. We show that no upper estimation is possible for digraphs. We also give some remarks on distances, which are either metric or non-metric.

**Keywords:** graph, digraph, strong digraph, radius, diameter

**Classification (MSC91):** 05C12; 05C20

**Full text of the article:**

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