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An alternative proof of Berg and Nikolaev’s characterization of CAT(0)-spaces via quadrilateral inequality

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Abstract

We give a short alternative proof of Berg and Nikolaev’s recent theorem on a characterization of CAT(0)-spaces via the quadrilateral inequality.

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  1. Department of Mathematics, Faculty of Science, Kyoto University, Kyoto, 606-8502, Japan

    Takashi Sato

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  1. Takashi Sato
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Correspondence to Takashi Sato.

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Sato, T. An alternative proof of Berg and Nikolaev’s characterization of CAT(0)-spaces via quadrilateral inequality. Arch. Math. 93, 487–490 (2009). https://doi.org/10.1007/s00013-009-0057-9

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  • DOI: https://doi.org/10.1007/s00013-009-0057-9

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