Jan Bydzovsky ; Jan Krajicek ; Igor C. Oliveira - Consistency of circuit lower bounds with bounded theories

lmcs:5578 - Logical Methods in Computer Science, June 18, 2020, Volume 16, Issue 2 - https://doi.org/10.23638/LMCS-16(2:12)2020
Consistency of circuit lower bounds with bounded theoriesArticle

Authors: Jan Bydzovsky ; Jan Krajicek ; Igor C. Oliveira

    Proving that there are problems in PNP that require boolean circuits of super-linear size is a major frontier in complexity theory. While such lower bounds are known for larger complexity classes, existing results only show that the corresponding problems are hard on infinitely many input lengths. For instance, proving almost-everywhere circuit lower bounds is open even for problems in MAEXP. Giving the notorious difficulty of proving lower bounds that hold for all large input lengths, we ask the following question: Can we show that a large set of techniques cannot prove that NP is easy infinitely often? Motivated by this and related questions about the interaction between mathematical proofs and computations, we investigate circuit complexity from the perspective of logic. Among other results, we prove that for any parameter k1 it is consistent with theory T that computational class Ci.o.SIZE(nk), where (T,C) is one of the pairs: T=T12 and C=PNP, T=S12 and C=NP, T=PV and C=P. In other words, these theories cannot establish infinitely often circuit upper bounds for the corresponding problems. This is of interest because the weaker theory PV already formalizes sophisticated arguments, such as a proof of the PCP Theorem. These consistency statements are unconditional and improve on earlier theorems of [KO17] and [BM18] on the consistency of lower bounds with PV.


    Volume: Volume 16, Issue 2
    Published on: June 18, 2020
    Accepted on: February 27, 2020
    Submitted on: June 17, 2019
    Keywords: Computer Science - Computational Complexity,Mathematics - Logic
    Funding:
      Source : OpenAIRE Graph
    • Algorithms and Lower Bounds: A Unified Approach; Funder: European Commission; Code: 615075
    • Interpolation properties for first-order Gödel logics; Funder: European Commission; Code: P 31955

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