Here is a source that might help you: http://ariadne.coli.uni-bielefeld.de/aat/Alexander_Mehler_and_Reinhard_Koehler.pdf#search=%22dimensionality%20reduction%20%20semiotics%22 http://www-rocq.inria.fr/imedia/Muscle/WP5/Docs/WP5_SoA_Task4_sept04.pdf#search=%22dimensionality%20reduction%20%20semiotics%22 {see page 20-21} http://staff.science.uva.nl/~worring/pub/papers/bagdanov-rectangular.pdf
