## Introduction To Dehn Surgery

Date Thursday, September 25, 2014

Using the Poincar&eacute; conjecture as motivation, I’ll introduce a construction of Max Dehn, now known as Dehn surgery, as a way of constructing counterexamples to Poincar&eacute; ’s first conjecture (but not his second conjecture, which is the famous one). Dehn’s construction was later (~1960's) shown to be an extremely versatile way of constructing 3-manifolds, and so has become a fundamental tool in the study of low-dimensional topology.