Current Topics Seminar


Speaker Paul Smith
Title Non-commutative geometry and Penrose tilings of the plane.
Date January 20 4:00pm PDL C-36
We explain how the ``non-commutative algebraic variety'' having homogeneous coordinate ring the free algebra k modulo the ideal generated by y^2 can be viewed as the space of Penrose tilings of the plane. Each Penrose tiling yields a ``point'' on this non-commutative variety and two tilings yield the same ``point'' if and only if one tiling can be obtained from the other by an isometry of the plane. This approach is entirely compatible with the approximately finite non-commutative C^*-algebra that Alain Connes associates to the space of Penrose tilings of the plane.