Fundamentals of Geometry

Following Hilbert, in our treatment of neutral geometry (called also absolute geometry and composed of facts true in both Euclidean and Lobachevskian geometries) we define points, lines, and planes as mathematical objects with the property that these objects, as well as some objects formed from them, like angles and triangles, satisfy the axioms listed in sections 1 through 4 of this chapter. We shall denote points, lines and planes by capital Latin A,B,C, . . .,
small Latin a, b, c, . . ., and small Greek α, β, γ, . . . letters respectively, possibly with subscripts...