51Mxx Real and complex geometry

51M04  Elementary problems in Euclidean geometries
51M05  Euclidean geometries (general) and generalizations
51M09  Elementary problems in hyperbolic and elliptic geometries
51M10  Hyperbolic and elliptic geometries (general) and
               generalizations
51M15  Geometric constructions
51M16  Inequalities and extremum problems, {For convex problems,
               See 52A40}
51M20  Polyhedra and polytopes; regular figures, division of
               spaces, See also {51F15}
51M25  Length, area and volume, See also {26B15}
51M30  Line geometries and their generalizations, See also {53A25}
51M35  Synthetic treatment of fundamental manifolds in projective
               geometries (Grassmannians, Veronesians and their
               generalizations), See also {14M15}
51M99  None of the above but in this section