A Better-Than-3n Lower Bound for the Circuit Complexity of an Explicit Function

2016 ◽  
Author(s):  
Magnus Gausdal Find ◽  
Alexander Golovnev ◽  
Edward A. Hirsch ◽  
Alexander S. Kulikov
Keyword(s):  
Lower Bound ◽  
Circuit Complexity ◽  
Explicit Function ◽  
Better Than

Bounded Elastic Moduli Multiplier Technique for Limit Loads: Part 2 - Case Studies

2021 ◽  
Author(s):  
Sathya Prasad Mangalaramanan
Keyword(s):  
Lower Bound ◽  
Case Studies ◽  
Power Law ◽  
Elastic Moduli ◽  
New Method ◽  
Stress Distributions ◽  
Limit Loads ◽  
Elastic Plastic ◽  
Thick Cylinder ◽  
Better Than

Abstract An accompanying paper provides the theoretical underpinnings of a new method to determine statically admissible stress distributions in a structure, called Bounded elastic moduli multiplier technique (BEMMT). It has been shown that, for textbook cases such as thick cylinder, beam, etc., the proposed method offers statically admissible stress distributions better than the power law and closer to elastic-plastic solutions. This paper offers several examples to demonstrate the robustness of this method. Upper and lower bound limit loads are calculated using iterative elastic analyses using both power law and BEMMT. These results are compared with the ones obtained from elastic-plastic FEA. Consistently BEMMT has outperformed power law when it comes to estimating lower bound limit loads.

scholarly journals Lower bounds to eigenvalues of the Schrödinger equation by solution of a 90-y challenge

2020 ◽  
Vol 117 (28) ◽  
pp. 16181-16186
Author(s):  
Rocco Martinazzo ◽  
Eli Pollak
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Upper Bound ◽  
Spectral Features ◽  
Numerical Examples ◽  
Tunneling Splittings ◽  
Order Of Magnitude ◽  
Bound Theorem ◽  
Math Phys ◽  
Better Than

The Ritz upper bound to eigenvalues of Hermitian operators is essential for many applications in science. It is a staple of quantum chemistry and physics computations. The lower bound devised by Temple in 1928 [G. Temple,Proc. R. Soc. A Math. Phys. Eng. Sci.119, 276–293 (1928)] is not, since it converges too slowly. The need for a good lower-bound theorem and algorithm cannot be overstated, since an upper bound alone is not sufficient for determining differences between eigenvalues such as tunneling splittings and spectral features. In this paper, after 90 y, we derive a generalization and improvement of Temple’s lower bound. Numerical examples based on implementation of the Lanczos tridiagonalization are provided for nontrivial lattice model Hamiltonians, exemplifying convergence over a range of 13 orders of magnitude. This lower bound is typically at least one order of magnitude better than Temple’s result. Its rate of convergence is comparable to that of the Ritz upper bound. It is not limited to ground states. These results complement Ritz’s upper bound and may turn the computation of lower bounds into a staple of eigenvalue and spectral problems in physics and chemistry.

scholarly journals A sharp lower bound on the signless Laplacian index of graphs with (κ,τ)-regular sets

2018 ◽  
Vol 6 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Milica Andeelić ◽  
Domingos M. Cardoso ◽  
António Pereira
Keyword(s):  
Lower Bound ◽  
Perfect Matching ◽  
Computational Experiments ◽  
Sufficient Condition ◽  
Hamiltonian Graphs ◽  
Laplacian Spectra ◽  
Signless Laplacian ◽  
Regular Sets ◽  
Sharp Lower Bound ◽  
Better Than

Abstract A new lower bound on the largest eigenvalue of the signless Laplacian spectra for graphs with at least one (κ,τ)regular set is introduced and applied to the recognition of non-Hamiltonian graphs or graphs without a perfect matching. Furthermore, computational experiments revealed that the introduced lower bound is better than the known ones. The paper also gives sufficient condition for a graph to be non Hamiltonian (or without a perfect matching).

scholarly journals Four by four MDS matrices with the fewest XOR gates based on words

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Shi Wang ◽  
Yongqiang Li ◽  
Shizhu Tian ◽  
Xiangyong Zeng
Keyword(s):  
Lower Bound ◽  
Block Ciphers ◽  
General Linear ◽  
Linear Groups ◽  
Mds Matrix ◽  
General Linear Groups ◽  
Significant Interest ◽  
Better Than

<p style='text-indent:20px;'>MDS matrices play an important role in the design of block ciphers, and constructing MDS matrices with fewer xor gates is of significant interest for lightweight ciphers. For this topic, Duval and Leurent proposed an approach to construct MDS matrices by using three linear operations in ToSC 2018. Taking words as elements, they found <inline-formula><tex-math id="M1">\begin{document}$ 16\times16 $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M2">\begin{document}$ 32\times 32 $\end{document}</tex-math></inline-formula> MDS matrices over <inline-formula><tex-math id="M3">\begin{document}$ \mathbb{F}_2 $\end{document}</tex-math></inline-formula> with only <inline-formula><tex-math id="M4">\begin{document}$ 35 $\end{document}</tex-math></inline-formula> xor gates and <inline-formula><tex-math id="M5">\begin{document}$ 67 $\end{document}</tex-math></inline-formula> xor gates respectively, which are also the best known implementations up to now. Based on the same observation as their work, we consider three linear operations as three kinds of elementary linear operations of matrices, and obtain more MDS matrices with <inline-formula><tex-math id="M6">\begin{document}$ 35 $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M7">\begin{document}$ 67 $\end{document}</tex-math></inline-formula> xor gates. In addition, some <inline-formula><tex-math id="M8">\begin{document}$ 16\times16 $\end{document}</tex-math></inline-formula> or <inline-formula><tex-math id="M9">\begin{document}$ 32\times32 $\end{document}</tex-math></inline-formula> involutory MDS matrices with only <inline-formula><tex-math id="M10">\begin{document}$ 36 $\end{document}</tex-math></inline-formula> or <inline-formula><tex-math id="M11">\begin{document}$ 72 $\end{document}</tex-math></inline-formula> xor gates over <inline-formula><tex-math id="M12">\begin{document}$ \mathbb{F}_2 $\end{document}</tex-math></inline-formula> are also proposed, which are better than previous results. Moreover, our method can be extended to general linear groups, and we prove that the lower bound of the sequential xor count based on words for <inline-formula><tex-math id="M13">\begin{document}$ 4 \times 4 $\end{document}</tex-math></inline-formula> MDS matrix over general linear groups is <inline-formula><tex-math id="M14">\begin{document}$ 8n+2 $\end{document}</tex-math></inline-formula>.</p>

scholarly journals Sunflower Theorems in Monotone Circuit Complexity

2021 ◽  
Author(s):  
Bruno Pasqualotto Cavalar ◽  
Yoshiharu Kohayakawa
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Circuit Complexity ◽  
Restricted Range ◽  
Significant Progress ◽  
Randomness Extractors ◽  
Monotone Circuits ◽  
Monotone Boolean Function ◽  
Sunflower Lemma ◽  
Clique Problem

Alexander Razborov (1985) developed the approximation method to obtain lower bounds on the size of monotone circuits deciding if a graph contains a clique. Given a "small" circuit, this technique consists in finding a monotone Boolean function which approximates the circuit in a distribution of interest, but makes computation errors in that same distribution. To prove that such a function is indeed a good approximation, Razborov used the sunflower lemma of Erd\H{o}s and Rado (1960). This technique was improved by Alon and Boppana (1987) to show lower bounds for a larger class of monotone computational problems. In that same work, the authors also improved the result of Razborov for the clique problem, using a relaxed variant of sunflowers. More recently, Rossman (2010) developed another variant of sunflowers, now called "robust sunflowers", to obtain lower bounds for the clique problem in random graphs. In the following years, the concept of robust sunflowers found applications in many areas of computational complexity, such as DNF sparsification, randomness extractors and lifting theorems. Even more recent was the breakthrough result of Alweiss, Lovett, Wu and Zhang (2020), which improved Rossman's bound on the size of hypergraphs without robust sunflowers. This result was employed to obtain a significant progress on the sunflower conjecture. In this work, we will show how the recent progress in sunflower theorems can be applied to improve monotone circuit lower bounds. In particular, we will show the best monotone circuit lower bound obtained up to now, breaking a 20-year old record of Harnik and Raz (2000). We will also improve the lower bound of Alon and Boppana for the clique function in a slightly more restricted range of clique sizes. Our exposition is self-contained. These results were obtained in a collaboration with Benjamin Rossman and Mrinal Kumar.

Inequalities with applications to percolation and reliability

1985 ◽  
Vol 22 (3) ◽  
pp. 556-569 ◽  
Author(s):  
J. Van Den Berg ◽  
H. Kesten
Keyword(s):  
Lower Bound ◽  
Probability Measure ◽  
Cluster Size ◽  
Discrete Analog ◽  
Reliability Theory ◽  
Probability Measures ◽  
Bond Percolation ◽  
Critical Probability ◽  
New Better Than Used ◽  
Better Than

A probability measure μ on ℝn+ is defined to be strongly new better than used (SNBU) if for all increasing subsets . For n = 1 this is equivalent to being new better than used (NBU distributions play an important role in reliability theory). We derive an inequality concerning products of NBU probability measures, which has as a consequence that if μ1, μ2, ···, μn are NBU probability measures on ℝ+, then the product-measure μ = μ × μ2 × ··· × μn on ℝn+ is SNBU. A discrete analog (i.e., with N instead of ℝ+) also holds.Applications are given to reliability and percolation. The latter are based on a new inequality for Bernoulli sequences, going in the opposite direction to the FKG–Harris inequality. The main application (3.15) gives a lower bound for the tail of the cluster size distribution for bond-percolation at the critical probability. Further applications are simplified proofs of some known results in percolation. A more general inequality (which contains the above as well as the FKG-Harris inequality) is conjectured, and connections with an inequality of Hammersley [12] and others ([17], [19] and [7]) are indicated.

NEW QUANTUM CODES CONSTRUCTED FROM A CLASS OF IMPRIMITIVE BCH CODES

2013 ◽  
Vol 11 (01) ◽  
pp. 1350006 ◽  
Author(s):  
YANG LIU ◽  
YUENA MA ◽  
YOUQIAN FENG ◽  
RUIHU LI
Keyword(s):  
Lower Bound ◽  
Prime Power ◽  
Careful Analysis ◽  
Bch Codes ◽  
Bch Code ◽  
Quantum Codes ◽  
Narrow Sense ◽  
Cyclotomic Cosets ◽  
Steane Construction ◽  
Better Than

By a careful analysis on cyclotomic cosets, the maximal designed distance δnew of narrow-sense imprimitive Euclidean dual containing q-ary BCH code of length [Formula: see text] is determined, where q is a prime power and l is odd. Our maximal designed distance δnew of dual containing narrow-sense BCH codes of length n improves upon the lower bound δmax for maximal designed distances of dual containing narrow-sense BCH codes given by Aly et al. [IEEE Trans. Inf. Theory53 (2007) 1183]. A series of non-narrow-sense dual containing BCH codes of length n, including the ones whose designed distances can achieve or exceed δnew, are given, and their dimensions are computed. Then new quantum BCH codes are constructed from these non-narrow-sense imprimitive BCH codes via Steane construction, and these new quantum codes are better than previous results in the literature.

Inequalities with applications to percolation and reliability

1985 ◽  
Vol 22 (03) ◽  
pp. 556-569 ◽  
Author(s):  
J. Van Den Berg ◽  
H. Kesten
Keyword(s):  
Lower Bound ◽  
Probability Measure ◽  
Cluster Size ◽  
Discrete Analog ◽  
Reliability Theory ◽  
Probability Measures ◽  
Bond Percolation ◽  
Critical Probability ◽  
New Better Than Used ◽  
Better Than

A probability measure μ on ℝn + is defined to be strongly new better than used (SNBU) if for all increasing subsets . For n = 1 this is equivalent to being new better than used (NBU distributions play an important role in reliability theory). We derive an inequality concerning products of NBU probability measures, which has as a consequence that if μ 1, μ 2, ···, μn are NBU probability measures on ℝ+, then the product-measure μ = μ × μ 2 × ··· × μn on ℝn + is SNBU. A discrete analog (i.e., with N instead of ℝ+) also holds. Applications are given to reliability and percolation. The latter are based on a new inequality for Bernoulli sequences, going in the opposite direction to the FKG–Harris inequality. The main application (3.15) gives a lower bound for the tail of the cluster size distribution for bond-percolation at the critical probability. Further applications are simplified proofs of some known results in percolation. A more general inequality (which contains the above as well as the FKG-Harris inequality) is conjectured, and connections with an inequality of Hammersley [12] and others ([17], [19] and [7]) are indicated.

Subgraph Reliability of Alternating Group Graph With Uniform and Nonuniform Vertex Fault-Free Probabilities

2020 ◽  
Author(s):  
Yanze Huang ◽  
Limei Lin ◽  
Li Xu
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Fault Model ◽  
Alternating Group ◽  
Multiprocessor System ◽  
Single Vertex ◽  
Arrangement Graph ◽  
Uniform Probability ◽  
Better Than ◽  
Alternating Group Graph

Abstract As the size of a multiprocessor system grows, the probability that faults occur in this system increases. One measure of the reliability of a multiprocessor system is the probability that a fault-free subsystem of a certain size still exists with the presence of individual faults. In this paper, we use the probabilistic fault model to establish the subgraph reliability for $AG_n$, the $n$-dimensional alternating group graph. More precisely, we first analyze the probability $R_n^{n-1}(p)$ that at least one subgraph with dimension $n-1$ is fault-free in $AG_n$, when given a uniform probability of a single vertex being fault-free. Since subgraphs of $AG_n$ intersect in rather complicated manners, we resort to the principle of inclusion–exclusion by considering intersections of up to five subgraphs and obtain an upper bound of the probability. Then we consider the probabilistic fault model when the probability of a single vertex being fault-free is nonuniform, and we show that the upper bound under these two models is very close to the lower bound obtained in a previous result, and it is better than the upper bound deduced from that of the arrangement graph, which means that the upper bound we obtained is very tight.

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