Ittai Abraham, Yair Bartal, Ofer Neiman. Embedding metrics into ultrametrics and graphs into spanning trees with constant average distortion. In Nikhil Bansal, Kirk Pruhs, Clifford Stein, editors, Proceedings of the Eighteenth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2007, New Orleans, Louisiana, USA, January 7-9, 2007. pages 502-511, SIAM, 2007. [doi]
Abstract is missing.