{"title":"Nearly optimal separations between communication (or query) complexity and partitions","authors":"Robin Kothari","doi":"10.4230/LIPIcs.CCC.2016.4","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2016.4","url":null,"abstract":"We show a nearly quadratic separation between deterministic communication complexity and the logarithm of the partition number, which is essentially optimal. This improves upon a recent power 1.5 separation of Goos, Pitassi, and Watson (FOCS 2015). In query complexity, we establish a nearly quadratic separation between deterministic (and even randomized) query complexity and subcube partition complexity, which is also essentially optimal. We also establish a nearly power 1.5 separation between quantum query complexity and subcube partition complexity, the first superlinear separation between the two measures. Lastly, we show a quadratic separation between quantum query complexity and one-sided subcube partition complexity. \u0000 \u0000Our query complexity separations use the recent cheat sheet framework of Aaronson, Ben-David, and Kothari. Our query functions are built up in stages by alternating function composition with the cheat sheet construction. The communication complexity separation follows from \"lifting\" the query separation to communication complexity.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120903792","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}
S. Aaronson, A. Ambainis, Janis Iraids, M. Kokainis, Juris Smotrovs
{"title":"Polynomials, Quantum Query Complexity, and Grothendieck's Inequality","authors":"S. Aaronson, A. Ambainis, Janis Iraids, M. Kokainis, Juris Smotrovs","doi":"10.4230/LIPIcs.CCC.2016.25","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2016.25","url":null,"abstract":"We show an equivalence between 1-query quantum algorithms and representations by degree-2 polynomials. Namely, a partial Boolean function $f$ is computable by a 1-query quantum algorithm with error bounded by $epsilon<1/2$ iff $f$ can be approximated by a degree-2 polynomial with error bounded by $epsilon'<1/2$. This result holds for two different notions of approximation by a polynomial: the standard definition of Nisan and Szegedy and the approximation by block-multilinear polynomials recently introduced by Aaronson and Ambainis (STOC'2015, arXiv:1411.5729). \u0000We also show two results for polynomials of higher degree. First, there is a total Boolean function which requires $tilde{Omega}(n)$ quantum queries but can be represented by a block-multilinear polynomial of degree $tilde{O}(sqrt{n})$. Thus, in the general case (for an arbitrary number of queries), block-multilinear polynomials are not equivalent to quantum algorithms. \u0000Second, for any constant degree $k$, the two notions of approximation by a polynomial (the standard and the block-multilinear) are equivalent. As a consequence, we solve an open problem of Aaronson and Ambainis, showing that one can estimate the value of any bounded degree-$k$ polynomial $p:{0, 1}^n rightarrow [-1, 1]$ with $O(n^{1-frac{1}{2k}})$ queries.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127890844","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":"A Linear Time Algorithm for Quantum 2-SAT","authors":"N. D. Beaudrap, Sevag Gharibian","doi":"10.4230/LIPIcs.CCC.2016.27","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2016.27","url":null,"abstract":"The Boolean constraint satisfaction problem 3-SAT is arguably the canonical NP-complete problem. In contrast, 2-SAT can not only be decided in polynomial time, but in fact in deterministic linear time. In 2006, Bravyi proposed a physically motivated generalization of k-SAT to the quantum setting, defining the problem \"quantum k-SAT\". He showed that quantum 2-SAT is also solvable in polynomial time on a classical computer, in particular in deterministic time O(n^4), assuming unit-cost arithmetic over a field extension of the rational numbers, where n is number of variables. In this paper, we present an algorithm for quantum 2-SAT which runs in linear time, i.e. deterministic time O(n+m) for n and m the number of variables and clauses, respectively. Our approach exploits the transfer matrix techniques of Laumann et al. [QIC, 2010] used in the study of phase transitions for random quantum 2-SAT, and bears similarities with both the linear time 2-SAT algorithms of Even, Itai, and Shamir (based on backtracking) [SICOMP, 1976] and Aspvall, Plass, and Tarjan (based on strongly connected components) [IPL, 1979].","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115538250","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":"How to Compress Asymmetric Communication","authors":"Sivaramakrishnan Natarajan Ramamoorthy, Anup Rao","doi":"10.4230/LIPIcs.CCC.2015.102","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.102","url":null,"abstract":"We study the relationship between communication and information in 2-party communication protocols when the information is asymmetric. If IA denotes the number of bits of information revealed by the first party, IB denotes the information revealed by the second party, and C is the number of bits of communication in the protocol, we show that \u0000 \u0000• one can simulate the protocol using order [EQUATION] bits of communication, \u0000 \u0000• one can simulate the protocol using order IA · 2O(IB) bits of communication. \u0000 \u0000The first result gives the best known bound on the complexity of a simulation when IA G IB,C3/4. The second gives the best known bound when IB L log C. In addition we show that if a function is computed by a protocol with asymmetric information complexity, then the inputs must have a large, nearly monochromatic rectangle of the right dimensions, a fact that is useful for proving lower bounds on lopsided communication problems.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127108267","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":"Correlation Bounds Against Monotone NC^1","authors":"Benjamin Rossman","doi":"10.4230/LIPIcs.CCC.2015.392","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.392","url":null,"abstract":"This paper gives the first correlation bounds under product distributions, including the uniform distribution, against the class mNC1 of polynomial-size O(log n)-depth monotone circuits. Our main theorem, proved using the pathset complexity framework introduced in [56], shows that the average-case k-CYCLE problem (on Erdos-Renyi random graphs with an appropriate edge density) is [EQUATION] hard for mNC1. Combining this result with O'Donnell's hardness amplification theorem [43], we obtain an explicit monotone function of n variables (in the class mSAC1) which is [EQUATION] hard for mNC1 under the uniform distribution for any desired constant e > 0. This bound is nearly best possible, since every monotone function has agreement [EQUATION] with some function in mNC1 [44]. \u0000 \u0000Our correlation bounds against mNC1 extend smoothly to non-monotone NC1 circuits with a bounded number of negation gates. Using Holley's monotone coupling theorem [30], we prove the following lemma: with respect to any product distribution, if a balanced monotone function f is [EQUATION] hard for monotone circuits of a given size and depth, then f is [EQUATION] hard for (non-monotone) circuits of the same size and depth with at most t negation gates. We thus achieve a lower bound against NC1 circuits with [EQUATION] log n negation gates, improving the previous record of 1/6 log log n [7]. Our bound on negations is \"half\" optimal, since ⌈log(n + 1)⌉ negation gates are known to be fully powerful for NC1 [3, 21].","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114968163","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":"Simplified Lower Bounds on the Multiparty Communication Complexity of Disjointness","authors":"Anup Rao, A. Yehudayoff","doi":"10.4230/LIPIcs.CCC.2015.88","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.88","url":null,"abstract":"We show that the deterministic number-on-forehead communication complexity of set disjointness for k parties on a universe of size n is Ω(n/ 4k). This gives the first lower bound that is linear in n, nearly matching Grolmusz's upper bound of O(log2(n) + k2n/2k). We also simplify the proof of Sherstov's [EQUATION] lower bound for the randomized communication complexity of set disjointness.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123697615","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":"A Depth-Five Lower Bound for Iterated Matrix Multiplication","authors":"S. Bera, Amit Chakrabarti","doi":"10.4230/LIPIcs.CCC.2015.183","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.183","url":null,"abstract":"We prove that certain instances of the iterated matrix multiplication (IMM) family of polynomials with N variables and degree n require [EQUATION] gates when expressed as a homogeneous depth-five ΣΠΣΠΣ arithmetic circuit with the bottom fan-in bounded by N1/2-e. By a depth-reduction result of Tavenas, this size lower bound is optimal and can be achieved by the weaker class of homogeneous depth-four ΣΠΣΠ circuits.Our result extends a recent result of Kumar and Saraf, who gave the same [EQUATION] lower bound for homogeneous depth-four ΣΠΣΠ circuits computing IMM. It is analogous to a recent result of Kayal and Saha, who gave the same lower bound for homogeneous ΣΠΣΠΣ circuits (over characteristic zero) with bottom fan-in at most N1-e, for the harder problem of computing certain polynomials defined by Nisan--Wigderson designs.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115867412","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":"Adaptivity Helps for Testing Juntas","authors":"R. Servedio, Li-Yang Tan, John Wright","doi":"10.4230/LIPIcs.CCC.2015.264","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.264","url":null,"abstract":"We give a new lower bound on the query complexity of any non-adaptive algorithm for testing whether an unknown Boolean function is a k-junta versus e-far from every k-junta. Our lower bound is that any non-adaptive algorithm must make \u0000 \u0000[EQUATION] \u0000 \u0000queries for this testing problem, where c is any absolute constant < 1. For suitable values of e this is asymptotically larger than the O(k log k + k/e) query complexity of the best known adaptive algorithm [9] for testing juntas, and thus the new lower bound shows that adaptive algorithms are more powerful than non-adaptive algorithms for the junta testing problem.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122010128","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":"Circuits with Medium Fan-In","authors":"P. Hrubes, Anup Rao","doi":"10.4230/LIPIcs.CCC.2015.381","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2015.381","url":null,"abstract":"We consider boolean circuits in which every gate may compute an arbitrary boolean function of k other gates, for a parameter k. We give an explicit function f : {0, 1}n → {0, 1} that requires at least Ω(log2 n) non-input gates when k = 2n/3. When the circuit is restricted to being layered and depth 2, we prove a lower bound of nΩ(1) on the number of non-input gates. When the circuit is a formula with gates of fan-in k, we give a lower bound Ω(n2/k log n) on the total number of gates. \u0000 \u0000Our model is connected to some well known approaches to proving lower bounds in complexity theory. Optimal lower bounds for the Number-On-Forehead model in communication complexity, or for bounded depth circuits in AC0, or extractors for varieties over small fields would imply strong lower bounds in our model. On the other hand, new lower bounds for our model would prove new time-space tradeoffs for branching programs and impossibility results for (fan-in 2) circuits with linear size and logarithmic depth. In particular, our lower bound gives a different proof for a known time-space tradeoff for oblivious branching programs.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114340787","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":"Sums of products of polynomials in few variables : lower bounds and polynomial identity testing","authors":"Mrinal Kumar, Shubhangi Saraf","doi":"10.4230/LIPIcs.CCC.2016.35","DOIUrl":"https://doi.org/10.4230/LIPIcs.CCC.2016.35","url":null,"abstract":"We study the complexity of representing polynomials as a sum of products of polynomials in few variables. More precisely, we study representations of the form $$P = sum_{i = 1}^T prod_{j = 1}^d Q_{ij}$$ such that each $Q_{ij}$ is an arbitrary polynomial that depends on at most $s$ variables. We prove the following results. \u00001. Over fields of characteristic zero, for every constant $mu$ such that $0 leq mu < 1$, we give an explicit family of polynomials ${P_{N}}$, where $P_{N}$ is of degree $n$ in $N = n^{O(1)}$ variables, such that any representation of the above type for $P_{N}$ with $s = N^{mu}$ requires $Td geq n^{Omega(sqrt{n})}$. This strengthens a recent result of Kayal and Saha [KS14a] which showed similar lower bounds for the model of sums of products of linear forms in few variables. It is known that any asymptotic improvement in the exponent of the lower bounds (even for $s = sqrt{n}$) would separate VP and VNP[KS14a]. \u00002. We obtain a deterministic subexponential time blackbox polynomial identity testing (PIT) algorithm for circuits computed by the above model when $T$ and the individual degree of each variable in $P$ are at most $log^{O(1)} N$ and $s leq N^{mu}$ for any constant $mu < 1/2$. We get quasipolynomial running time when $s < log^{O(1)} N$. The PIT algorithm is obtained by combining our lower bounds with the hardness-randomness tradeoffs developed in [DSY09, KI04]. To the best of our knowledge, this is the first nontrivial PIT algorithm for this model (even for the case $s=2$), and the first nontrivial PIT algorithm obtained from lower bounds for small depth circuits.","PeriodicalId":246506,"journal":{"name":"Cybersecurity and Cyberforensics Conference","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133182711","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}