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| | DOCUMENTA MATHEMATICA, Quadratic Forms LSU (2001), 121-139 (Site not responding. Last check: 2007-09-18) |
 | | In contrast, the first paper that studied metric spaces {\em as such} -- without trying to study their embeddability into any one of the standard metric spaces nor looking at them as mere `presentations' of the underlying topological space -- was, to our knowledge, written in the late sixties by John Isbell. |
 | | In particular, Isbell showed that in the category whose objects are metric spaces and whose morphisms are {\em non-expansive} maps, a unique {\em injective hull} exists for every object, he provided an explicit construction of this hull, and he noted that, at least for finite spaces, it comes endowed with an intrinsic polytopal cell structure. |
 | | In this paper, we discuss Isbell's construction, we summarize the history of --- and some basic questions studied in --- {\it phylogenetic analysis}, and we explain why and how these two topics are related to each other. |
| www.ii.uj.edu.pl /EMIS/journals/DMJDMV/lsu/dress-huber-multon.html (218 words) |
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