{"title":"Efficient Arguments without Short PCPs","authors":"Y. Ishai, E. Kushilevitz, R. Ostrovsky","doi":"10.1109/CCC.2007.10","DOIUrl":"https://doi.org/10.1109/CCC.2007.10","url":null,"abstract":"Current constructions of efficient argument systems combine a short (polynomial size) PCP with a cryptographic hashing technique. We suggest an alternative approach for this problem that allows to simplify the underlying PCP machinery using a stronger cryptographic technique. More concretely, we present a direct method for compiling an exponentially long PCP which is succinctly described by a linear oracle function pi : F^n to F into an argument system in which the verifier sends to the prover O(n) encrypted field elements and receives O(1) encryptions in return. This compiler can be based on an arbitrary homomorphic encryption scheme. Applying our general compiler to the exponential size Hadamard code based PCP of Arora et al. (JACM 1998) yields a simple argument system for NP in which the communication from the prover to the verifier only includes a constant number of short encryptions. The main tool we use is a new cryptographic primitive which allows to efficiently commit to a linear function and later open the output of the function on an arbitrary vector. Our efficient implementation of this primitive is independently motivated by cryptographic applications.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131990137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Heuristic Time Hierarchies","authors":"Konstantin Pervyshev","doi":"10.1109/CCC.2007.20","DOIUrl":"https://doi.org/10.1109/CCC.2007.20","url":null,"abstract":"We study the existence of time hierarchies for heuristic algorithms. We prove that a time hierarchy exists for heuristic algorithms in such syntactic classes as NP and co-NP, and also in semantic classes AM and MA. Further, we present an alternative approach to proving time hierarchies for heuristic algorithms in BPP. This leads to a simpler proof than the one known before.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114482865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Testing Properties of Constraint-Graphs","authors":"S. Halevy, Oded Lachish, I. Newman, Dekel Tsur","doi":"10.1109/CCC.2007.31","DOIUrl":"https://doi.org/10.1109/CCC.2007.31","url":null,"abstract":"We study a model of graph related formulae that we call the constraint-graph model. A constraint-graph is a labeled multi-graph (a graph where loops and parallel edges are allowed), where each edge e is labeled by a distinct Boolean variable and every vertex is associated with a Boolean function over the variables that label its adjacent edges. A Boolean assignment to the variables satisfies the constraint graph if it satisfies every vertex function. We associate with a constraint-graph G the property that consists of all assignments satisfying G, denoted SAT(G). We show that the above model is quite general. That is, for every property of strings P there exists a property of constraint-graphs PG such that P is testable using q queries if and only if PG is thus testable. In addition, we present a large family of constraint-graphs for which SAT(G) is testable with constant number of queries. As an implication of this, we infer the testability of some edge coloring problems (e.g. the property of two coloring of the edges in which every node is adjacent to at least one vertex of each color). Another implication is that every property of Boolean strings that can be represented by a read-twice CNF formula is testable. We note that this is the best possible in terms of the number of occurrences of every variable in a formula.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114405925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Understanding Parallel Repetition Requires Understanding Foams","authors":"U. Feige, Guy Kindler, R. O'Donnell","doi":"10.1109/CCC.2007.39","DOIUrl":"https://doi.org/10.1109/CCC.2007.39","url":null,"abstract":"Motivated by the study of parallel repetition and also by the unique games conjecture, we investigate the value of the \"odd cycle games\" under parallel repetition. Using tools from discrete harmonic analysis, we show that after d rounds on the cycle of length m, the value of the game is at most 1-(1/m)ldrOmega macr(radicd) (for dlesm2, say). This beats the natural barrier of 1-Theta(1/m)2 ldrd for Raz-style proofs and also the SDP bound of Feige-Lovasz; however, it just barely fails to have implications for unique games. On the other hand, we also show that improving our bound would require proving nontrivial lower bounds on the surface area of high-dimensional foams. Specifically, one would need to answer: what is the least surface area of a cell that tiles Rd by the lattice Zd?","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115275363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Complexity of Polynomials and Their Coefficient Functions","authors":"Guillaume Malod","doi":"10.1109/CCC.2007.33","DOIUrl":"https://doi.org/10.1109/CCC.2007.33","url":null,"abstract":"We study the link between the complexity of a polynomial and that of its coefficient functions. Valiant's theory is a good setting for this, and we start by generalizing one of Valiant's observations, showing that the class VNP is stable for coefficient functions, and that this is true of the class VP iff VP=VNP, an eventuality which would be as surprising as the equality of the classes P and NP in Boolean complexity. We extend the definition of Valiant's classes to polynomials of unbounded degree, thus defining the classes VPnb and VNPnb. Over rings of positive characteristic the same kind of results hold in this case, and we also prove that VP=VNP iff VPnb=VNPnb. Finally, we use our extension of Valiant's results to show that iterated partial derivatives can be efficiently computed iff VP=VNP. This is also true for the case of polynomials of unbounded degree, if the characteristic of the ring is positive.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128260628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Computation and Communication with Small Bias","authors":"H. Buhrman","doi":"10.1007/978-3-540-74871-7_1","DOIUrl":"https://doi.org/10.1007/978-3-540-74871-7_1","url":null,"abstract":"","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132086114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Unbalanced Expanders and Randomness Extractors from Parvaresh-Vardy Codes","authors":"V. Guruswami, C. Umans, Salil P. Vadhan","doi":"10.1145/1538902.1538904","DOIUrl":"https://doi.org/10.1145/1538902.1538904","url":null,"abstract":"We give an improved explicit construction of highly unbalanced bipartite expander graphs with expansion arbitrarily close to the degree (which is polylogarithmic in the number of vertices). Both the degree and the number of right-hand vertices are polynomially close to optimal, whereas the previous constructions of Ta-Shma, Umans, and Zuckerman (STOC \"01) required at least one of these to be quasipolynomial in the optimal. Our expanders have a short and self-contained description and analysis, based on the ideas underlying the recent list-decodable error-correcting codes of Parvaresh and Vardy (FOCS \"05). Our expanders can be interpreted as near-optimal \"randomness condensers,\" that reduce the task of extracting randomness from sources of arbitrary min-entropy rate to extracting randomness from sources of min-entropy rate arbitrarily close to 1, which is a much easier task. Using this connection, we obtain a new construction of randomness extractors that is optimal up to constant factors, while being much simpler than the previous construction of Lu et al. (STOC \"03) and improving upon it when the error parameter is small (e.g. 1/poly(n)).","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129105801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On C-Degrees, H-Degrees and T-Degrees","authors":"W. Merkle, F. Stephan","doi":"10.1109/CCC.2007.17","DOIUrl":"https://doi.org/10.1109/CCC.2007.17","url":null,"abstract":"Following a line of research that aims at relating the computation power and the initial segment complexity of a set, the work presented here investigates into the relations between Turing reducibility, defined in terms of computation power, and C-reducibility and H-reducibility, defined in terms of the complexity of initial segments. The global structures of all C-degrees and of all H-degrees are rich and allows to embed the lattice of the powerset of the natural numbers under inclusion. In particular, there are C-degrees, as well as H-degrees, that are different from the least degree and are the meet of two other degrees, whereas on the other hand there are pairs of sets that have a meet neither in the C-degrees nor in the H-degrees; these results answer questions in a survey by Nies and Miller. There are r.e. sets that form a minimal pair for C-reducibility and Sigma2 0 sets that form a minimal pair for H-reducibility, which answers questions by Downey and Hirschfeldt. Furthermore, the following facts on the relation between C-degrees, H-degrees and Turing degrees hold. Every C-degree contains at most one Turing degree and this bound is sharp since there are C-degrees that do contain a Turing degree. For the comprising class of complex sets, neither the C-degree nor the H-degree of such a set can contain a Turing degree, in fact, the Turing degree of any complex set contains infinitely many C-degrees. Similarly the Turing degree of any set that computes the halting problem contains infinitely many H-degrees, while the H-degree of any 2-random set R is never contained in the Turing degree of R. By the latter, H-equivalence of Martin-Lof random sets does not imply their Turing equivalence. The structure of the Cdegrees contained in the Turing degree of a complex sets is rich and allows to embed any countable distributive lattice; a corresponding statement is true for the structure of H-degrees that are contained in the Turing degree of a set that computes the halting problem.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"370 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125724814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Parity Problems in Planar Graphs","authors":"M. Braverman, R. Kulkarni, Sambuddha Roy","doi":"10.1109/CCC.2007.23","DOIUrl":"https://doi.org/10.1109/CCC.2007.23","url":null,"abstract":"We consider the problem of counting the number of spanning trees in planar graphs. We prove tight bounds on the complexity of the problem, both in general and especially in the modular setting. We exhibit the problem to be complete for Logspace when the modulus is 2k, for constant k. On the other hand, we show that for any other modulus and in the non-modular case, our problem is as hard in the planar case as for the case of arbitrary graphs. This completely settles the question regarding the complexity of modular computation of the number of spanning trees in planar graphs. The techniques used rely heavily on algebraic-topology. In the spirit of counting problems modulo 2k, we also exhibit a highly parallel oplusL algorithm for finding the value of a Permanent modulo 2k. Previously, the best known result in this direction was Valiant's result that this problem lies in P.","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127618746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bounded Queries and the NP Machine Hypothesis","authors":"Richard Chang, Suresh Purini","doi":"10.1109/CCC.2007.7","DOIUrl":"https://doi.org/10.1109/CCC.2007.7","url":null,"abstract":"The NP machine hypothesis posits the existence of an in ge 0 and a nondeterministic polynomial-time Turing machine M which accepts the language 0 but for which no deterministic Turing machine running in 2^n time can output an accepting path infinitely often. This paper shows two applications of the NP machine hypothesis in bounded query complexity. First, if the NP machine hypothesis holds, then P^SAT[1] = P^SAT[2] Rightarrow PH subseteq NP. Without assuming the NP machine hypothesis, the best known collapse of the Polynomial Hierarchy (PH) is to the class S_2^P due to a result of Fortnow, Pavan and Sengupta [9]. The second application is to bounded query function classes. If the NP machine hypothesis holds then for all constants d ge 0, there exists a constant k ge d such that for all oracles X, PF^SAT[n^k] notsubset PF^X[n^d]. In particular, PF^SAT[n^d] varsubsetneq PF^SAT[n^k]. Without the NP machine hypothesis, there are currently no known consequences even if for all k ge 1, PF^SAT[n^k] subseteq PF^SAT[n].","PeriodicalId":175854,"journal":{"name":"Twenty-Second Annual IEEE Conference on Computational Complexity (CCC'07)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134345155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}