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Logic seminar

Semi-Algebraic Proofs, IPS lower bounds and the tau-Conjecture

Iddo Tzameret
Royal Holloway, University of London


Monday, 4. May 2020 - 13:30 to 15:00 - meeting ID: 472 648 284
We introduce the binary value principle which is a simple subset-sum instance expressing that a natural number written in binary cannot be negative, relating it to problems in proof and algebraic complexity. We prove conditional superpolynomial lower bounds on the Ideal Proof System (IPS) refutation size of this instance, based on a well-known hypothesis by Shub and Smale about the hardness of computing factorials, where IPS is the strong algebraic proof system introduced by Grochow and Pitassi (2014). Conversely, we show that short IPS refutations of this instance bridge the gap between sufficiently strong algebraic and semi-algebraic proof systems. Our results extend to full-fledged IPS the paradigm introduced in Forbes, Shpilka, Tzameret and Wigderson (2016), whereby lower bounds against subsystems of IPS were obtained using restricted algebraic circuit lower bounds, and demonstrate that the binary value principle captures the advantage of semi-algebraic over algebraic reasoning, for sufficiently strong systems.

Joint work with Yaroslav Alekseev, Dima Grigoriev and Edward A. Hirsch. See full version here: