Department of         Mathematical Sciences Events People Colloquia and Seminars Conferences Centers Positions Areas of Research About the Department Alumni Math Colloquium Boris Bukh Carnegie Mellon University, refreshments at 4:00, WeH 6220. Title: Convex and stairconvex geometries Abstract: Convex sets are combinatorially complicated because convexity is defined via addition and multiplication. Stairconvex sets are siblings of convex sets, whose definition involves no arithmetic, and that form a geometry of their own. I shall describe the solutions to several problems in classic combinatorial convexity that use stairconvex sets, and will mention the still-mysterious connections with algebraic topology and logic.Date: Tuesday, January 29, 2013Time: 4:30 pmLocation: Wean 8220Submitted by:  Bohman