Approximately Finite Geometries and Their Coordinate Rings

Introduction: Von Newmann [8]¹ has discovered a class of geometries in which the undefined elements are subspaces and the undefined operations are meets and joins of subspaces. His axioms require that the system consisting of the set ℒ of subspaces together with the two operations form an irreducible, complete, complemented, modular lattice satisfying an additional dual pair of continuity of conditions.