Chinese remainder theorem, Apr 15, 2014, Slides [PDF] 
Differential Geometry of Graphs,Nov 16, 2012, Bridgewater Slides [PDF], Clips [M4V] for Ipod. 
Geometry of Networks, Apr 1, 2012, Math Circle Handout [PDF], Slides [PDF], [Smartphone media] 

Polyhedra and Polytopes, Dec 6, 2009, Math Circle Handout [PDF], Slides I [PDF], Slides II [PDF], [Ipod I], [Ipod II] 
Treasure Hunting Perfect Euler Bricks, Feb 24, 2009 Math table Handout [PDF], Map [PDF] 
How Chaos inspires other disciplines, Feb 7, 2008, SCI Slides [PDF, 44Meg] To lecture [PDF] [Ipod, 220Meg]  
The oldest unsolved problem in mathematics,Dec 2, 2007, Math Circle Handout [PDF] Slides [PDF] [Ipod] 
The structure from motion problem, Oct 29, 2007, Colby Slides [PDF], 
On the mathematics of panorama photography,Jul 11, 2007, Summer school Slides [PDF]  
Mathematics and AI, Apr 1, 2007, math Circle Handout [PDF] [Ipod] 
A lecture on Diophantine equations, Apr 30, 2006, math circle [PDF] 
An hour on complex numbers, Sept 2004, Math warmup Handout [PDF] Problems [PDF] Slides [PDF]  
Fashion in Mathematics, May 2004, mathcircle Handout [PDF] 
Billiards, Nov 2003, Math Circle [PDF] 
Billiards, Dec, 1999, Mathtable (actually interview talk) [PDF] 