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A geodesic metric space is called a tree-graded space with respect to a collection of connected proper subsets called pieces, if any two distinct pieces intersect in at most one point, and every non-trivial simple geodesic triangle of is contained in one of the pieces.

If the pieces have bounded diameter, tree-graded spaces behave like real trees in their coarse geometry (in the sense of Gromov), while allowing non-tree-like behavior within the pieces.[ citation needed]

Tree-graded spaces were introduced by Cornelia Druţu and Mark Sapir ( 2005) in their study of the asymptotic cones of hyperbolic groups.

References

  • Druţu, Cornelia; Sapir, Mark (2005), "Tree-graded spaces and asymptotic cones of groups", Topology, 44 (5): 959–1058, arXiv: math/0405030, doi: 10.1016/j.top.2005.03.003, MR  2153979.