In August 2012 Shinichi Mochizuki posted his four preprints which develop a new inter-universal Teichmüller theory, with an alleged application to the proof of several famous conjectures including the "abc" conjecture.
In August 2012 Shinichi Mochizuki posted his four preprints which develop a new inter-universal Teichmüller theory (IUT) based on anabelian geometry. The fourth paper applied IUT to obtain the proof of several famous conjectures including the "abc" conjecture.