Über Erweiterungen von Z und Z2 * Z2 durch nichteuklidische kristallographische Gruppen.
Über Gruppen von Homöomorphismen Seifertscher Faserräume und flacher Manigfaltigkeiten.
Ultra regular covering space and its automorphism group
In order to classify digital spaces in terms of digital-homotopic theoretical tools, a recent paper by Han (2006b) (see also the works of Boxer and Karaca (2008) as well as Han (2007b)) established the notion of regular covering space from the viewpoint of digital covering theory and studied an automorphism group (or Deck's discrete transformation group) of a digital covering. By using these tools, we can calculate digital fundamental groups of some digital spaces and classify digital covering spaces...
Un nouvel invariant pour les sphères d'homologie de dimension trois
Une obstruction pour scinder une équivalence d’homotopie en dimension