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The SOM partitions the input space into
convex Voronoi regions, each of which corresponds to one unit of the map.
The Voronoi region of a map unit *i* is the union of all vectors
to which it is the closest one:

In the Voronoi region the reference vector can be shown to be placed
according to the local conditional expectation of the data weighted
by the neighborhood kernel:

*Juha Vesanto *

Tue May 27 12:40:37 EET DST 1997