  This thesis opens with an introductory discussion, where the reader is gently
led to the world of topological combinatorics, and, where the results of this
Habilitationsschrift are portrayed against the backdrop of the broader
philosophy of the subject. That introduction is followed by 5 chapters, where
the main body of research is presented, and 4 appendices, where various
standard tools and notations, which we use throughout the text, are collected.
