Department of Computer Science | Institute of Theoretical Computer Science | CADMO

Theory of Combinatorial Algorithms

Prof. Emo Welzl and Prof. Bernd Gärtner

Mittagsseminar (in cooperation with A. Steger, D. Steurer and B. Sudakov)

Mittagsseminar Talk Information

Date and Time: Tuesday, April 13, 2004, 12:15 pm

Duration: This information is not available in the database

Location: This information is not available in the database

Speaker: Andreas Paffenholz (TU Berlin)

New Polytopes derived from Products

Recently J. Bokowski and G. Gevay presented a new family S_{mn} of self-dual 3-spheres based on a construction of G. Gevay. This family contains in particular the hypersimplex and the 24-cell.

In my talk I will show that this family of spheres is a very special case of the 'E-construction'. This method was invented by D. Eppstein, G. Kuperberg and G. M. Ziegler for the construction of 2-simple and 2-simplicial 4-polytopes and subsequently extended to arbitrary polytopes and, more general, to lattices by G. M. Ziegler and myself.

The family of spheres S_{mn} can be derived from products (C_m x C_n) of two polygons C_m and C_n with m resp. n vertices. We prove that all these spheres are in fact polytopal with flexible geometric realizations. For 1/m+1/n>=1/2 we obtain ``symmetric'' realizations of these polytopes, while such realizations cannot exist for other m,n. We will in particular discuss the realization space of the hypersimplex and the 24-cell.

Upcoming talks     |     All previous talks     |     Talks by speaker     |     Upcoming talks in iCal format (beta version!)

Previous talks by year:   2024  2023  2022  2021  2020  2019  2018  2017  2016  2015  2014  2013  2012  2011  2010  2009  2008  2007  2006  2005  2004  2003  2002  2001  2000  1999  1998  1997  1996  

Information for students and suggested topics for student talks

Automatic MiSe System Software Version 1.4803M   |   admin login