Fu Li, Iddo Tzameret, Zhengyu Wang. Non-Commutative Formulas and Frege Lower Bounds: a New Characterization of Propositional Proofs. In David Zuckerman, editor, 30th Conference on Computational Complexity, CCC 2015, June 17-19, 2015, Portland, Oregon, USA. Volume 33 of LIPIcs, pages 412-432, Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik, 2015. [doi]
Abstract is missing.