L'ultramétrique inférieure maximum d'une dissimilarité à valeurs dans un inf-demi treillis

摘要

Dissimilarity functions are usually defined to take values in the set R+ of nonnegative reals. This set has various properties as, for instance, those related to the intrinsec linear order of R. But many authors have shown that a number of basic results relative to dissimilarity functions are preserved when R+ is replaced by any partially ordered set. In this paper we propose two methods for the fitting of a given dissimilarity approximation by the subdominant ultrametric when this dissimilarity takes values in a meet semi-lattice.