Thévenaz, JacquesKsontini, Rached2009-11-132009-11-132009-11-132000https://infoscience.epfl.ch/handle/20.500.14299/44219The fundamental group of the Quillen complex of the symmetric group is studied and the cases where the complex is simply-connected are determined. Other results concerning the homology groups are also proved.thesis::doctoral thesis