The Self-Organizing Map (SOM) with its related extensions is the most popular
artificial neural algorithm for use in unsupervised learning, clustering,
classification and data visualization. Over 5,000 publications have been
reported in the open literature, and many commercial projects employ the SOM as
a tool for solving hard real-world problems. Each two years, the "Workshop on
Self-Organizing Maps" (WSOM) covers the new developments in the field. The WSOM
series of conferences was initiated in 1997 by Prof. Teuvo Kohonen, and has
been successfully organized in 1997 and 1999 by the Helsinki University of
Technology, in 2001 by the University of Lincolnshire and Humberside, and in
2003 by the Kyushu Institute of Technology. The Universit\'{e} Paris I
Panth\'{e}on Sorbonne (SAMOS-MATISSE research centre) organized WSOM 2005 in
Paris on September 5-8, 2005.Comment: Special Issue of the Neural Networks Journal after WSOM 05 in Pari