On the combination theorem for negatively curved groups. (English) Zbl 0879.20014

Author’s abstract: We give a simple proof of a sufficient condition for an amalgamated free product of two negatively curved groups to be negatively curved, and we compute the curvature of such products.


20F65 Geometric group theory
20E06 Free products of groups, free products with amalgamation, Higman-Neumann-Neumann extensions, and generalizations
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