Fri, 11 Feb 2011 13:30:37 +0000 | urbanc | included comments by Xingyuan | changeset | files |
Fri, 11 Feb 2011 12:13:35 +0000 | urbanc | slightly streamlined the proof | changeset | files |
Thu, 10 Feb 2011 21:00:40 +0000 | urbanc | simplified a bit the proof | changeset | files |