Complex sentence: In geometry, a ten-dimensional polytope, or 10-polytope, is a polytope in 10-dimensional space, each 8-polytope ridge being shared by exactly two 9-polytope facets.
Split into simpler sentences: In geometry, a ten-dimensional polytope, or 10-polytope, is a polytope in 10-dimensional space. Each 8-polytope ridge being shared by exactly two 9-polytope facets.