Toniann Pitassi Benjamin Rossman Rocco A. Servedio Li-Yang Tan Poly-logarithmic Frege depth lower bounds via an expander switching lemma. 644-657 2016 STOC https://doi.org/10.1145/2897518.2897637 conf/stoc/2016 db/conf/stoc/stoc2016.html#PitassiRST16