Tropical Geometry

Linfield College textbook that approaches geometry through the question of the shape of the universe. Covers Euclidean, hyperbolic, and elliptic geometry on the way to a primer on cosmic topology.

Michael P. Hitchman

Concise 27-page introduction to projective geometry from a Master MOSIG course, covering projective spaces, transformations of the line and plane, and conics in the projective setting.

Edmond Boyer