Von Neumann worked on lattice theory between 1937 and 1939. Von Neumann provided an abstract exploration of dimension in completed complemented modular topological lattices: "Dimension is determined, up to a positive linear transformation, by the following two properties. It is <answer>conserved by perspective mappings ("perspectivities") and ordered by inclusion</answer>. The deepest part of the proof concerns the equivalence of perspectivity with "projectivity by decomposition"—of which a corollary is the transitivity of perspectivity." Garrett Birkhoff writes: "John von Neumann's brilliant mind blazed over lattice theory like a meteor".
What properties determine dimension in lattice theory?
conserved by perspective mappings ("perspectivities") and ordered by inclusion