Embedding Metrics into Ultrametrics and Graphs into Spanning Trees with Constant Average Distortion

Ittai Abraham Yair Bartal Ofer Neiman Embedding Metrics into Ultrametrics and Graphs into Spanning Trees with Constant Average Distortion http://arxiv.org/abs/cs/0610003 2006 CoRR abs/cs/0610003 db/journals/corr/corr0610.html#abs-cs-0610003 informal publication