New a-T-menable HNN-extensions. Gal, Światosław R.; Januszkiewicz, Tadeusz — 2003 Journal of Lie Theory
Euler characteristic of the configuration space of a complex Światosław R. Gal — 2001 Colloquium Mathematicae A closed form formula (generating function) for the Euler characteristic of the configuration space of n particles in a simplicial complex is given.