We study two graph parameters, namely the geodetic number and the Steiner number, which are related to the concept of convexity. We show that, in asteroidal triple-free graphs, the Steiner number is greater than or equal to the geodetic number. This answers a question posed by Hernando, Jiang, Mora, Pelayo, and Seara in 2005. Besides, we show that the gap between the two parameters can be arbitrarily large even in unit-interval graphs, a proper subclass of AT-free graphs. (C) 2020 Elsevier B.V. All rights reserved.
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Univ Fed Rio de Janeiro, Inst Matemat, Dept Ciencia Comp, Rio De Janeiro, BrazilUniv Fed Rio de Janeiro, Inst Matemat, Dept Ciencia Comp, Rio De Janeiro, Brazil
Dourado, Mitre C.
Penso, Lucia D.
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Univ Ulm, Inst Optimizat & Operat Res, Ulm, GermanyUniv Fed Rio de Janeiro, Inst Matemat, Dept Ciencia Comp, Rio De Janeiro, Brazil
Penso, Lucia D.
Rautenbach, Dieter
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Univ Ulm, Inst Optimizat & Operat Res, Ulm, GermanyUniv Fed Rio de Janeiro, Inst Matemat, Dept Ciencia Comp, Rio De Janeiro, Brazil