%0 Journal Article %A Sean Gasiorek %T Counting Collisions in an $N$-Billiard System Using Angles Between Collision Subspaces %J Symmetry, integrability and geometry: methods and applications %D 2020 %V 16 %U http://geodesic.mathdoc.fr/item/SIGMA_2020_16_a118/ %G en %F SIGMA_2020_16_a118