The branch of affine geometry in which one studies invariants of centro-affine transformations: . Centro-affine transformations leave one point (the centre) fixed. In centro-affine geometry there is complete duality: To every proposition concerning points corresponds the same proposition concerning hyperplanes.
Centro-affine geometry. L.A. Sidorov (originator), Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Centro-affine_geometry&oldid=12060