Characteristic Properties by Examples
As explained in the previous chapter, the
PSOM builds a parameterized associative map. Employing the
described class of generalized multi-dimensional Lagrange
polynomials as basis functions facilitates the construction of
very versatile PSOM mapping manifolds. Resulting unusual
characteristics and properties are exposed in this chapter.
Several aspects find description: topological order introduces
model bias to the PSOM and strongly influences the
interpretation of the training data; the influence of
non-regularities in the process of sampling the training data is
explored; “topological defects” can occur, e.g. if the
correspondence of input and output data is mistaken; The use of
basis polynomials affects the PSOM extrapolation properties.
Furthermore, in some cases the given mapping task faces the
best-match procedure with the problem of non-continuities or
multiple solutions. Since the visualization of multi-dimensional
mappings embedded in even higher dimensional spaces is
difficult, the next section illustrates stepwise several PSOM
examples. They start with small numbers of nodes.
5.1 Illustrated Mappings – Constructed From a
Small Number of Points
The first mapping example is a
two-dimensional (
m
) PSOM mapping manifold with
reference vectors in a
four-dimensional (d
) dimen-


