Interplay between coding theory and combinatorial $t$-designs has been a hot topic for many years for combinatorialists and coding theorists. Some infinite families of cyclic codes supporting infinite families of $3$-designs have been constructed in the past 50 years. However, no infinite family of negacyclic codes supporting an infinite family of $3$-designs has been reported in the literature. This is the main motivation of this paper. Let $q=p^m$, where $p$ is an odd prime and $m \geq 2$ is an integer. The objective of this paper is to present an infinite family of cyclic codes over $\gf(q)$ supporting an infinite family of $3$-designs and two infinite families of negacyclic codes over $\gf(q^2)$ supporting two infinite families of $3$-designs. The parameters and the weight distributions of these codes are determined. The subfield subcodes of these negacyclic codes over $\gf(q)$ are studied. Three infinite families of almost MDS codes are also presented. A constacyclic code over GF($4$) supporting a $4$-design and six open problems are also presented in this paper.
The graph parameter of pathwidth can be seen as a measure of the topological resemblance of a graph to a path. A popular definition of pathwidth is given in terms of node search where we are given a system of tunnels that is contaminated by some infectious substance and we are looking for a search strategy that, at each step, either places a searcher on a vertex or removes a searcher from a vertex and where an edge is cleaned when both endpoints are simultaneously occupied by searchers. It was proved that the minimum number of searchers required for a successful cleaning strategy is equal to the pathwidth of the graph plus one. Two desired characteristics for a cleaning strategy is to be monotone (no recontamination occurs) and connected (clean territories always remain connected). Under these two demands, the number of searchers is equivalent to a variant of pathwidth called {\em connected pathwidth}. We prove that connected pathwidth is fixed parameter tractable, in particular we design a $2^{O(k^2)}\cdot n$ time algorithm that checks whether the connected pathwidth of $G$ is at most $k.$ This resolves an open question by [Dereniowski, Osula, and Rz{\k{a}}{\.{z}}ewski, Finding small-width connected path-decompositions in polynomial time. Theor. Comput. Sci., 794:85-100, 2019]. For our algorithm, we enrich the typical sequence technique that is able to deal with the connectivity demand. Typical sequences have been introduced in [Bodlaender and Kloks. Efficient and constructive algorithms for the pathwidth and treewidth of graphs. J. Algorithms, 21(2):358-402, 1996] for the design of linear parameterized algorithms for treewidth and pathwidth. The proposed extension is based on an encoding of the connectivity property that is quite versatile and may be adapted so to deliver linear parameterized algorithms for the connected variants of other width parameters as well.
The mystery about the ingenious creator of Bitcoin concealing behind the pseudonym Satoshi Nakamoto has been fascinating the global public for more than a decade. Suddenly jumping out of the dark in 2008, this persona hurled the decentralized electronic cash system "Bitcoin", which has reached a peak market capitalization in the region of 1 trillion USD. In a purposely agnostic, and meticulous "lea-ving no stone unturned" approach, this study presents new hard facts, which evidently slipped through Satoshi Nakamoto's elaborate privacy shield, and derives meaningful pointers that are primarily inferred from Bitcoin's whitepaper, its blockchain parameters, and data that were widely up to his discretion. This ample stack of established and novel evidence is systematically categorized, analyzed, and then connected to its related, real-world ambient, like relevant locations and happenings in the past, and at the time. Evidence compounds towards a substantial role of the Benelux cryptography ecosystem, with strong transatlantic links, in the creation of Bitcoin. A consistent biography, a psychogram, and gripping story of an ingenious, multi-talented, autodidactic, reticent, and capricious polymath transpire, which are absolutely unique from a history of science and technology perspective. A cohort of previously fielded and best matches emerging from the investigations are probed against an unprecedently restrictive, multi-stage exclusion filter, which can, with maximum certainty, rule out most "Satoshi Nakamoto" candidates, while some of them remain to be confirmed. With this article, you will be able to decide who is not, or highly unlikely to be Satoshi Nakamoto, be equipped with an ample stack of systematically categorized evidence and efficient methodologies to find suitable candidates, and can possibly unveil the real identity of the creator of Bitcoin - if you want.
One of the most robust patterns found in human languages is Zipf's law of abbreviation, that is, the tendency of more frequent words to be shorter. Since Zipf's pioneering research, this law has been viewed as a manifestation of compression, i.e. the minimization of the length of forms - a universal principle of natural communication. Although the claim that languages are optimized has become trendy, attempts to measure the degree of optimization of languages have been rather scarce. Here we demonstrate that compression manifests itself in a wide sample of languages without exceptions, and independently of the unit of measurement. It is detectable for both word lengths in characters of written language as well as durations in time in spoken language. Moreover, to measure the degree of optimization, we derive a simple formula for a random baseline and present two scores that are dualy normalized, namely, they are normalized with respect to both the minimum and the random baseline. We analyze the theoretical and statistical pros and cons of these and other scores. Harnessing the best score, we quantify for the first time the degree of optimality of word lengths in languages. This indicates that languages are optimized to 62 or 67 percent on average (depending on the source) when word lengths are measured in characters, and to 65 percent on average when word lengths are measured in time. In general, spoken word durations are more optimized than written word lengths in characters. Beyond the analyses reported here, our work paves the way to measure the degree of optimality of the vocalizations or gestures of other species, and to compare them against written, spoken, or signed human languages.
A common approach to localize a mobile robot is by measuring distances to points of known positions, called anchors. Locating a device from distance measurements is typically phrased as a non-convex optimization problem, stemming from the nonlinearity of the measurement model. Non-convex optimization problems may yield suboptimal solutions when local iterative solvers such as Gauss-Newton are employed. In this paper, we design an optimality certificate for continuous-time range-only localization. Our formulation allows for the integration of a motion prior, which ensures smoothness of the solution and is crucial for localizing from only a few distance measurements. The proposed certificate comes at little additional cost since it has the same complexity as the sparse local solver itself: linear in the number of positions. We show, both in simulation and on real-world datasets, that the efficient local solver often finds the globally optimal solution (confirmed by our certificate) and when it does not, simple random reinitialization eventually leads to the certifiable optimum.
This work contributes to the limited literature on estimating the diffusivity or drift coefficient of nonlinear SPDEs driven by additive noise. Assuming that the solution is measured locally in space and over a finite time interval, we show that the augmented maximum likelihood estimator introduced in Altmeyer, Reiss (2020) retains its asymptotic properties when used for semilinear SPDEs that satisfy some abstract, and verifiable, conditions. The proofs of asymptotic results are based on splitting the solution in linear and nonlinear parts and fine regularity properties in $L^p$-spaces. The obtained general results are applied to particular classes of equations, including stochastic reaction-diffusion equations. The stochastic Burgers equation, as an example with first order nonlinearity, is an interesting borderline case of the general results, and is treated by a Wiener chaos expansion. We conclude with numerical examples that validate the theoretical results.
Non-Euclidean data is currently prevalent in many fields, necessitating the development of novel concepts such as distribution functions, quantiles, rankings, and signs for these data in order to conduct nonparametric statistical inference. This study provides new thoughts on quantiles, both locally and globally, in metric spaces. This is realized by expanding upon metric distribution function proposed by Wang et al. (2021). Rank and sign are defined at both the local and global levels as a natural consequence of the center-outward ordering of metric spaces brought about by the local and global quantiles. The theoretical properties are established, such as the root-$n$ consistency and uniform consistency of the local and global empirical quantiles and the distribution-freeness of ranks and signs. The empirical metric median, which is defined here as the 0th empirical global metric quantile, is proven to be resistant to contaminations by means of both theoretical and numerical approaches. Quantiles have been shown valuable through extensive simulations in a number of metric spaces. Moreover, we introduce a family of fast rank-based independence tests for a generic metric space. Monte Carlo experiments show good finite-sample performance of the test. Quantiles are demonstrated in a real-world setting by analysing hippocampal data.
We extend results known for the randomized Gauss-Seidel and the Gauss-Southwell methods for the case of a Hermitian and positive definite matrix to certain classes of non-Hermitian matrices. We obtain convergence results for a whole range of parameters describing the probabilities in the randomized method or the greedy choice strategy in the Gauss-Southwell-type methods. We identify those choices which make our convergence bounds best possible. Our main tool is to use weighted l1-norms to measure the residuals. A major result is that the best convergence bounds that we obtain for the expected values in the randomized algorithm are as good as the best for the deterministic, but more costly algorithms of Gauss-Southwell type. Numerical experiments illustrate the convergence of the method and the bounds obtained. Comparisons with the randomized Kaczmarz method are also presented.
Motivated by applications in distributed storage, distributed computing, and homomorphic secret sharing, we study communication-efficient schemes for computing linear combinations of coded symbols. Specifically, we design low-bandwidth schemes that evaluate the weighted sum of $\ell$ coded symbols in a codeword $\pmb{c}\in\mathbb{F}^n$, when we are given access to $d$ of the remaining components in $\pmb{c}$. Formally, suppose that $\mathbb{F}$ is a field extension of $\mathbb{B}$ of degree $t$. Let $\pmb{c}$ be a codeword in a Reed-Solomon code of dimension $k$ and our task is to compute the weighted sum of $\ell$ coded symbols. In this paper, for some $s<t$, we provide an explicit scheme that performs this task by downloading $d(t-s)$ sub-symbols in $\mathbb{B}$ from $d$ available nodes, whenever $d\geq \ell|\mathbb{B}|^s-\ell+k$. In many cases, our scheme outperforms previous schemes in the literature. Furthermore, we provide a characterization of evaluation schemes for general linear codes. Then in the special case of Reed-Solomon codes, we use this characterization to derive a lower bound for the evaluation bandwidth.
The Swapped Dragonfly with M routers per group and K global ports per router is denoted D3(K;M) [1]. It has n=KMM routers and is a partially populated Dragonfly. A Swapped Dragonfly with K and M restricted is studied in this paper. There are four cases. matrix product: If K is a perfect square, a matrix product of size n can be performed in squareroot n rounds. all-to-all exchange: If K and M have a common factor s, an all-to-all exchange can be performed in n/s rounds. broadcast: If D3(K,M) is equipped with a synchronized source-vector header it can perform x broadcast in 3x/M rounds. ascend-descend: If K and M are powers of 2 an ascend-descend algorithm can be performed at twice the cost of the algorithm on a Boolean hypercube of size n. In each case the algorithm on the Swapped Dragonfly is free of link conflicts and is compared with algorithms on a hypercube as well as on the fully populated Dragonfly. The results on the Swapped Dragonfly are more applicable than the special cases because D3(K,M) contains emulations of every Swapped Dragonfly with J less than equal to K and/or L less than or equal to M. Keywords: Swapped Interconnection Network, Matrix Product, All-to-all, Universal Exchange, Boolean Hypercube, Ascend-descend algorithm, Broad- cast, Edge-disjoint spanning tree. References [1] R. Draper. The Swapped Dragonfly , ArXiv for Computer Science:2202.01843. 1
Learning the underlying casual structure, represented by Directed Acyclic Graphs (DAGs), of concerned events from fully-observational data is a crucial part of causal reasoning, but it is challenging due to the combinatorial and large search space. A recent flurry of developments recast this combinatorial problem into a continuous optimization problem by leveraging an algebraic equality characterization of acyclicity. However, these methods suffer from the fixed-threshold step after optimization, which is not a flexible and systematic way to rule out the cycle-inducing edges or false discoveries edges with small values caused by numerical precision. In this paper, we develop a data-driven DAG structure learning method without the predefined threshold, called adaptive NOTEARS [30], achieved by applying adaptive penalty levels to each parameters in the regularization term. We show that adaptive NOTEARS enjoys the oracle properties under some specific conditions. Furthermore, simulation experimental results validate the effectiveness of our method, without setting any gap of edges weights around zero.