THE models are six in number. They are intended to show a line (1) by its projections, (2) by its traces; the inclination of an oblique plane (3) to the vertical plane, (4) to the horizontal plane; ...

Noncommutative geometry offers a radical reformulation of traditional geometrical concepts by replacing the classical notion of a manifold with a noncommutative algebra of coordinates. This approach ...

Around 1900, mathematicians across the world acquired physical models, both to illustrate concepts they taught and to demonstrate their familiarity with new ideas. They frequently purchased models ...