TR06-001 Authors: Ran Raz, Iddo Tzameret

Publication: 2nd January 2006 16:28

Downloads: 1372

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We introduce an algebraic proof system that manipulates multilinear arithmetic formulas. We show that this proof system is fairly strong, even when restricted to multilinear arithmetic formulas of a very small depth. Specifically, we show the following:

1. Algebraic proofs manipulating depth 2 multilinear arithmetic formulas polynomially simulate Resolution, Polynomial Calculus (PC) and polynomial Calculus with Resolution (PCR) proofs;

2. Polynomial size proofs manipulating depth 3 multilinear arithmetic formulas for the functional pigeonhole principle;

3. Polynomial size proofs manipulating depth 3 multilinear arithmetic formulas for Tseitin?s graph tautologies.

By known lower bounds, this demonstrates that algebraic proof systems manipulating depth 3 multilinear arithmetic formulas are strictly stronger than Resolution, PC and PCR, and have an exponential gap over bounded-depth Frege for both the functional pigeonhole principle and

Tseitin?s graph tautologies.

We also illustrate a connection between lower bounds on multilinear proofs and lower bounds on multilinear arithmetic circuits. In particular, we show that (an explicit) superpolynomial size separation between proofs manipulating general arithmetic circuits and proofs

manipulating multilinear arithmetic circuits implies a super-polynomial size lower bound on multilinear arithmetic circuits for an explicit family of polynomials.