Greek mathematician who was mainly interested in practical studies in mechanics and engineering, best known for Heron's Formula

Wrote treatise, the Mathematical Collection, as a guide to Greek geometry, discusses theorems and constructions of more than thirty different mathematicians of antiquity.

Plücker's assistant at Bonn who studied Analytic Geometry, describing geometry as the study of properties of figures which remain invariant under a Group of Transformations. He systemized Non-Euclidean Geometry.

Was one of the greatest contributors to projective geometry.