ERRATA

As mentioned in the editorial, we publish here five papers introducing the small group discussions. The authors of these papers and the editorial board wish to emphasize that these papers were not presented with a view to publication, and thus they do not pretend to be independent and original contributions.

However, the editorial board regarded these papers as valuable in various ways, and they are also illustrative of some of the variations of the theme of the congress. The papers are published here in only a slightly revised form.