We consider proofcomplexity in light of the unusual binary encoding of certain combinatorial principles. We contrast this proofcomplexity with the normal unary encoding in several refutation systems, based on Resolu...
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We consider proofcomplexity in light of the unusual binary encoding of certain combinatorial principles. We contrast this proofcomplexity with the normal unary encoding in several refutation systems, based on Resolution and Sherali-Adams. We first consider Res(s), which is an extension of Resolution working on s-DNFs (Disjunctive Normal Form formulas). We prove an exponential lower bound of n(Omega(k)/d(s)) for the size of refutations of the binary version of the k-Clique Principle in Res(s), where s = o ((log log n)(1/3)) and d(s) is a doubly exponential function. Our result improves that of Lauria et al., who proved a similar lower bound for Res(1), i.e., Resolution. For the k-Clique and other principles we study, we show how lower bounds in Resolution for the unary version follow from lower bounds in Res(log n) for the binary version, so we start a systematic study of the complexity of proofs in Resolution-based systems for families of contradictions given in the binary encoding. We go on to consider the binary version of the (weak) Pigeonhole Principle Bin-PHPnm. We prove that for any delta, epsilon > 0, Bin-PHPnm requires refutations of size 2(n1-delta) in Res(s) for s = O(log(1/2-epsilon) n). Our lower bound cannot be improved substantially with the same method since for m >= 2(root n) (log) (n) we can prove there are 2(O) ((root n) (log) (n)) size refutations of Bin-PHPnm in Res (log n). This is a consequence of the same upper bound for the unary weak Pigeonhole Principle of Buss and Pitassi. We contrast unary versus binary encoding in the Sherali-Adams (SA) refutation system where we prove lower bounds for both rank and size. For the unary encoding of the Pigeonhole Principle and the Ordering Principle, it is known that linear rank is required for refutations in SA, although both admit refutations of polynomial size. We prove that the binary encoding of the (weak) Pigeonhole Principle Bin-PHPnm requires exponentially sized (in n) SA refutations, whereas th
We construct a succinct non-interactive argument (SNARG) system for every NP language L that has a propositionalproof of non-membership, i.e. of x is not an element of L. The soundness of our SNARG system relies on t...
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ISBN:
(纸本)9798400703836
We construct a succinct non-interactive argument (SNARG) system for every NP language L that has a propositionalproof of non-membership, i.e. of x is not an element of L. The soundness of our SNARG system relies on the hardness of the learning with errors (LWE) problem. The common reference string (CRS) in our construction grows with the space required to verify the propositionalproof, and the size of the proof grows poly-logarithmically in the length of the propositionalproof. Unlike most of the literature on SNARGs, our result implies SNARGs for languages L with proof length shorter than logarithmic in the deterministic time complexity of L. Our SNARG improves over prior SNARGs for such "hard" NP languages (Sahai and Waters, STOC 2014, Jain and Jin, FOCS 2022) in several ways: 1) For languages with polynomial-length propositionalproofs of non-membership, our SNARGs are based on a single, polynomialtime falsifiable assumption, namely LWE. 2) Our construction handles super-polynomial length propositionalproofs, as long as they have bounded space, under the subex-ponential LWE assumption. 3) Our SNARGs have a transparent setup, meaning that no private randomness is required to generate the CRS. Moreover, our approach departs dramatically from these prior works: we show how to design SNARGs for hard languages without publishing a program (in the CRS) that has the power to verify NP witnesses. The key new idea in our construction is what we call a "locally unsatisable extension" of the NP verication circuit {C-x}(x). We say that an NP verifier has a locally unsatisfiable extension if for every x is not an element of L, there exists an extension E-x of C-x that is not even locally satisfiable in the sense of a local assignment generator [Paneth-Rothblum, TCC 2017]. Crucially, we allow E-x to be depend arbitrarily on G rather than being efficiently constructible. In this work, we show - via a "hash-and-BARG" for a hidden, encrypted computation - how to build SNARGs
The proof system Res(PCd, (R)) is a natural extension of the Resolution proof system that instead of disjunctions of literals operates with disjunctions of degree d multivariate polynomials over a ring R with Boolean ...
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The proof system Res(PCd, (R)) is a natural extension of the Resolution proof system that instead of disjunctions of literals operates with disjunctions of degree d multivariate polynomials over a ring R with Boolean variables. Proving super-polynomial lower bounds for the size of Res( PC1, (R))-refutations of Conjunctive normal forms (CNFs) is one of the important problems in propositional proof complexity. The existence of such lower bounds is even open for Res( PC1,(F)) when F is a finite field, such as F-2. In this article, we investigate Res(PCd, (R)) and tree-like Res(PCd, (R)) and prove size-width relations for them when R is a finite ring. As an application, we prove new lower bounds and reprove some known lower bounds for every finite field F as follows: (1) We prove almost quadratic lower bounds for Res(PCd, F)-refutations for every fixed d. The new lower bounds are for the following CNFs: (a) Mod q Tseitin formulas (char (F) not equal q) and Flow formulas, (b) Random k-CNFs with linearly many clauses. (2) We also prove super-polynomial (more than nk for any fixed k) and also exponential (2(n epsilon) for an epsilon > 0) lower bounds for tree-like Res(PCd, F)-refutations based on how big d is with respect to n for the following CNFs: (a) Mod q Tseitin formulas (char (F) not equal q) and Flow formulas, (b) Random k-CNFs of suitable densities, (c) Pigeonhole principle and Counting mod q principle. The lower bounds for the dag-like systems are the first nontrivial lower bounds for these systems, including the case d = 1. The lower bounds for the tree-like systems were known for the case d = 1 (except for the Counting mod q principle, in which lower bounds for the case d > 1 were known too). Our lower bounds extend those results to the case where d > 1 and also give new proofs for the case d = 1.
We prove a limitation on a variant of the KPT theorem proposed for propositionalproof systems by Pich and Santhanam [7], for all proof systems that prove the disjointness of two NP sets that are hard to distinguish.
We prove a limitation on a variant of the KPT theorem proposed for propositionalproof systems by Pich and Santhanam [7], for all proof systems that prove the disjointness of two NP sets that are hard to distinguish.
作者:
Capelli, FlorentUniv Lille
INRIA UMR 9189 CRIStAL Ctr Rech Informat Signal & Automat Lille F-59000 Lille France
In this paper, we study proof systems in the sense of Cook-Reckhow for problems that are higher in the Polynomial Hierarchy than coNP, in particular, #SAT and maxSAT. We start by explaining how the notion of Cook-Reck...
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ISBN:
(数字)9783030242589
ISBN:
(纸本)9783030242589;9783030242572
In this paper, we study proof systems in the sense of Cook-Reckhow for problems that are higher in the Polynomial Hierarchy than coNP, in particular, #SAT and maxSAT. We start by explaining how the notion of Cook-Reckhow proof systems can be apply to these problems and show how one can twist existing languages in knowledge compilation such as decision DNNF so that they can be seen as proof systems for problems such as #SAT and maxSAT.
In [7], Iemhoff introduced a special form of sequent-style rules and axioms, which she called focused, and studied the relationship between the focused proof systems, the systems only consisting of this kind of rules ...
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ISBN:
(纸本)9783662595336;9783662595329
In [7], Iemhoff introduced a special form of sequent-style rules and axioms, which she called focused, and studied the relationship between the focused proof systems, the systems only consisting of this kind of rules and axioms, and the uniform interpolation of the logic that the system captures. Subsequently, as a negative consequence of this relationship, she excludes almost all super-intuitionistic logics from having these focused proof systems. In this paper, we will provide a complexity theoretic analogue of her negative result to show that even in the cases that these systems exist, their proof-length would computationally explode. More precisely, we will first introduce two natural subclasses of focused rules, called PPF and MPF rules. Then, we will introduce some CPC-valid (IPC-valid) sequents with polynomially short tree-like proofs in the usual Hilbert-style proof system for classical logic, or equivalently LK + Cut, that have exponentially long proofs in the systems only consisting of PPF (MPF) rules.
We consider three relatively strong families of subsystems of AC(0)[2]-Frege proof systems, i.e., propositionalproof systems using constant-depth formulas with an additional parity connective, for which exponential l...
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We consider three relatively strong families of subsystems of AC(0)[2]-Frege proof systems, i.e., propositionalproof systems using constant-depth formulas with an additional parity connective, for which exponential lower bounds on proof size are known. In order of increasing strength, the subsystems are (i) constant-depth proof systems with parity axioms and the (ii) treelike and (iii) daglike versions of systems introduced by Krajicek which we call PKdc (circle plus). In a PKdc (circle plus)-proof, lines are disjunctions (cedents) in which all disjuncts have depth at most d, parities can only appear as the outermost connectives of disjuncts, and all but c disjuncts contain no parity connective at all. We prove that treelike PKO(1)O(1) (circle plus) is quasipolynomially but not polynomially equivalent to constant-depth systems with parity axioms. We also verify that the technique for separating parity axioms from parity connectives due to Impagliazzo and Segerlind can be adapted to give a superpolynomial separation between daglike PKO(1)O(1) (circle plus) and AC(0)[2]-Frege;the technique is inherently unable to prove superquasipolynomial separations. We also study proof systems related to the system Res-Lin introduced by Itsykson and Sokolov. We prove that an extension of treelike Res-Lin is polynomially simulated by a system related to daglike PKO(1)O(1) (circle plus), and obtain an exponential lower bound for this system.
We show that any polynomial-size Frege refutation of a certain linear-size unsatisfiable 3-CNF formula over n variables must have depth Omega(root log n). This is an exponential improvement over the previous best resu...
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ISBN:
(纸本)9781450341325
We show that any polynomial-size Frege refutation of a certain linear-size unsatisfiable 3-CNF formula over n variables must have depth Omega(root log n). This is an exponential improvement over the previous best results (Pitassi et al. 1993, Krajicek et al. 1995, Ben-Sasson 2002) which give Omega(log log n) lower bounds. The 3-CNF formulas which we use to establish this result are Tseitin contradictions on 3-regular expander graphs. In more detail, our main result is a proof that for every d, any depth-d Frege refutation of the Tseitin contradiction over these n-node graphs must have size n(Omega((log n)/d2)). A key ingredient of our approach is a new switching lemma for a carefully designed random restriction process over these expanders. These random restrictions reduce a Tseitin instance on a 3-regular n-node expander to a Tseitin instance on a random subgraph which is a topological embedding of a 3-regular n'-node expander, for some n' which is not too much less than n. Our result involves Omega (root log n) iterative applications of this type of random restriction.
The ordering principle states that every finite linear order has a least element. We show that, in the relativized setting, the surjective weak pigeonhole principle for polynomial time functions does not prove a Herbr...
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The ordering principle states that every finite linear order has a least element. We show that, in the relativized setting, the surjective weak pigeonhole principle for polynomial time functions does not prove a Herbrandized version of the ordering principle over T-2(1). This answers an open question raised in Buss et al. [2012] and completes their program to compare the strength of Jerabek's bounded arithmetic theory for approximate counting with weakened versions of it.
Random 3CNF formulas constitute an important distribution for measuring the average-case behavior of propositionalproof systems. Lower bounds for random 3CNF refutations in many propositionalproof systems are known....
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Random 3CNF formulas constitute an important distribution for measuring the average-case behavior of propositionalproof systems. Lower bounds for random 3CNF refutations in many propositionalproof systems are known. Most notable are the exponential-size resolution refutation lower bounds for random 3CNF formulas with Omega(n(1.5-epsilon)) clauses (Chvatal and Szemeredi [14], Ben-Sasson and Wigderson [10]). On the other hand, the only known non-trivial upper bound on the size of random 3CNF refutations in a non-abstract propositionalproof system is for resolution with Omega(n(2)/log n) clauses, shown by Beame et al. [6]. In this paper we show that already standard propositionalproof systems, within the hierarchy of Frege proofs, admit short refutations for random 3CNF formulas, for sufficiently large clause-to-variable ratio. Specifically, we demonstrate polynomial-size propositional refutations whose lines are TC0 formulas (i.e., TC0-Frege proofs) for random 3CNF formulas with n variables and Omega(n(1.4)) clauses. The idea is based on demonstrating efficient propositional correctness proofs of the random 3CNF unsatisfiability witnesses given by Feige, Kim and Ofek [23]. Since the soundness of these witnesses is verified using spectral techniques, we develop an appropriate way to reason about eigenvectors in propositional systems. To carry out the full argument we work inside weak formal systems of arithmetic and use a general translation scheme to propositionalproofs. (C) 2014 Elsevier B.V. All rights reserved.
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