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Volume 22 (2026) Article 4 pp. 1-29
CCC 2021 Special Issue
A Lower Bound for Polynomial Calculus with Extension Rule
Received: August 12, 2021
Revised: September 20, 2025
Published: June 21, 2026
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Keywords: proof complexity, algebraic proofs, polynomial calculus
ACM Classification: F.1.3
AMS Classification: 03F20

Abstract: [Plain Text Version]

$ \newcommand{\Q}{{\mathbb Q}} $

A major proof complexity problem is to prove a superpolynomial lower bound on the length of Frege proofs of arbitrary depth. A more difficult question is to prove an Extended Frege lower bound. Surprisingly, proving such bounds turns out to be much easier in the algebraic setting. In this paper, we study a proof system that can efficiently simulate Extended Frege: an extension of the Polynomial Calculus proof system where we can take a square root and introduce new variables that are equivalent to algebraic circuits of arbitrary depth. We prove that an instance of the subset-sum principle, the binary value principle $1 + x_1 + 2 x_2 + \ldots + 2^{n - 1} x_n = 0$ ($\mathsf{BVP}_n$), requires refutations of exponential bit size over $\Q$ in this system.

Part and Tzameret (ITCS'20) proved an exponential lower bound on the size of Res-Lin (Resolution over linear equations) refutations of $\mathsf{BVP}_n\,.$ We show that our system p-simulates Res-Lin and thus we get an alternative exponential lower bound for the size of Res-Lin refutations of $\mathsf{BVP}_n\,.$

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A preliminary version of this paper appeared in the Proceedings of the 36th Conference on Computational Complexity (CCC'21).