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Ever since the Tempe police released a video of Uber's selfdriving car hitting and killing a pedestrian, experts have been racing to analyze the footage and determine what exactly went wrong. (If you haven't watched the video, you can do so here. Warning: it's disturbing, though the actual impact is removed.) In a blog post, software architect and entrepreneur Brad Templeton highlights some of the big issues with the video: 1. On this empty road, the LIDAR is very capable of detecting her. If it was operating, there is no way that it did not detect her 3 to 4 seconds before the impact, if not earlier. She would have come into range just over 5 seconds before impact. 2.On the dashcam style video, we only see her 1.5 seconds before impact. However, the human eye and quality cameras have a much better dynamic range than this video, and should have also been able to see her even before 5 seconds. From just the dashcam video, no human could brake in time with just 1.5 seconds warning.
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BMW will not mass produce electric cars until 2020 because its current technology is not profitable enough to scale up for volume production, the chief executive said on Thursday. From a report: Munichbased BMW unveiled its first battery electric car in 2013, and has been working on different generations of battery, software and electric motor technology since then. The i8 Roadster model, due to hit showrooms in May, is equipped with what BMW calls its fourthgeneration electric drive technology. Advances in battery raw materials and chemistry has increased its range by 40 percent over the previous version, BMW said. BMW is working to make electric car technology more modular and scalable to make mass production commercially viable. "We wanted to wait for the fifth generation to be much more cost competitive," Chief Executive Harald Krueger told analysts in Munich. "We do not want to scale up with the fourth generation."
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An anonymous reader shares a report: The pedestrian killed Sunday by a selfdriving Uber SUV had crossed at least one open lane of road before being hit, according to a video of the crash that raises new questions about autonomousvehicle technology. Forensic crash analysts who reviewed the video said a human driver could have responded more quickly to the situation, potentially saving the life of the victim, 49yearold Elaine Herzberg. Other experts said Uber's selfdriving sensors should have detected the pedestrian as she walked a bicycle across the open road at 10 p.m., despite the dark conditions. Herzberg's death is the first major test of a nascent autonomous vehicle industry that has presented the technology as safer than humans who often get distracted while driving. For human driving in the U.S., there's roughly one death every 86 million miles, while autonomous vehicles have driven no more than 15 to 20 million miles in the country so far, according to Morgan Stanley analys
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An anonymous reader quotes a report from Ars Technica: The city of Atlanta government has apparently become the victim of a ransomware attack. The city's official Twitter account announced that the city government "is currently experiencing outages on various customer facing applications, including some that customers may use to pay bills or access courtrelated information." According to a report from Atlanta NBC affiliate WXIA, a city employee sent the station a screen shot of a ransomware message demanding a payment of $6,800 to unlock each computer or $51,000 to provide all the keys for affected systems. Employees received emails from the city's information technology department instructing them to unplug their computers if they noticed anything suspicious. An internal email shared with WXIA said that the internal systems affected include the city's payroll application. "At this time, our Atlanta Information Management team is working diligently with support from Microsoft to resol
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Before Facebook suspended Aleksandr Kogan from its platform for the data harvesting "scam" at the centre of the unfolding Cambridge Analytica scandal, the social media company enjoyed a close enough relationship with the researcher that it provided him with an anonymised, aggregate dataset of 57bn Facebook friendships. From a report: Facebook provided the dataset of "every friendship formed in 2011 in every country in the world at the national aggregate level" to Kogan's University of Cambridge laboratory for a study on international friendships published in Personality and Individual Differences in 2015. Two Facebook employees were named as coauthors of the study, alongside researchers from Cambridge, Harvard and the University of California, Berkeley. Kogan was publishing under the name Aleksandr Spectre at the time. A University of Cambridge press release on the study's publication noted that the paper was "the first output of ongoing research collaborations between Spectre's lab i
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The geometric Fierz identities are here employed to generate new emergent fermionic fields on the parallelizable (curvatureless, torsionfull) 7sphere ($S^7$). Employing recently found new classes of spinor fields on the $S^7$ spin bundle, new classes of fermionic fields are obtained from their bilinear covariants by a generalized reconstruction theorem, on the parallelizable $S^7$. Using a generalized nonassociative product on the octonionic bundle on the parallelizable $S^7$, these new classes of algebraic spinor fields, lifted onto the parallelizable $S^7$, are shown to correctly transform under the Moufang loop generators on $S^7$.
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In earlier work in collaboration with Pavel Galashin and Thomas McConville we introduced a version of chipfiring for root systems. Our investigation of root system chipfiring led us to define certain polynomials analogous to Ehrhart polynomials of lattice polytopes, which we termed the symmetric and truncated Ehrhartlike polynomials. We conjectured that these polynomials have nonnegative integer coefficients. Here we affirm "half" of this positivity conjecture by providing a positive, combinatorial formula for the coefficients of the symmetric Ehrhartlike polynomials. This formula depends on a subtle integrality property of slices of permutohedra which may be of independent interest. We also discuss how our formula very naturally suggests a conjecture for the coefficients of the truncated Ehrhartlike polynomials that turns out to be false in general, but which may hold in some cases.
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We observe that automorphism groups of rightangled Artin groups contain nilpotent nonabelian subgroups, namely $H_3(\mathbb{Z})$ the threedimensional integer Heisenberg group, provided they admit a certain type of element, called an adjacent transvection. This represents a (minor) extension of a result of CharneyVogtmann.
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In this work, we propose an Action Principle for Actiondependent Lagrangian functions by generalizing the Herglotz variational problem to the case with several independent variables. We obtain a necessary condition for the extremum equivalent to the EulerLagrange equation and, through some examples, we show that this generalized Action Principle enables us to construct simple and physically meaningful Actiondependent Lagrangian functions for a wide range of nonconservative classical and quantum systems. Furthermore, when the dependence on the Action is removed, the traditional Action Principle for conservative systems is recovered.
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We consider a structure $\mathcal {M} = \langle \mathbb N, \{Tr,<\} \rangle$, where the relation $Tr(a,x,y)$ with a parameter $ a$ defines a family of trees on $\mathbb N$ and $<$ is the usual order on $\mathbb N$. We show that if the elementary theory of $\mathcal M$ is decidable then (1) the relation $Q( a) \rightleftharpoons$ "there is an infinite branch in the tree $Tr( a,x,y)$" is definable in $\mathcal M$, and (2) if there is an infinite branch in the tree $Tr( a,x,y)$, then there is a definable in $\mathcal M$ infinite branch.
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One of the phenomena that influences significantly the performance of lowdensity paritycheck codes is known as trapping sets. An $(a,b)$ elementary trapping set, or simply an ETS where $a$ is the size and $b$ is the number of degreeone check nodes and $\frac{b}{a}<1$, causes high decoding failure rate and exert a strong influence on the error floor. In this paper, we provide sufficient conditions for exponent matrices to have fully connected $(3,n)$regular QCLDPC codes with girths 6 and 8 whose Tanner graphs are free of small ETSs. Applying sufficient conditions on the exponent matrix to remove some 8cycles results in removing all 4cycles, 6cycles as well as some small elementary trapping sets. For each girth we obtain a lower bound on the lifting degree and present exponent matrices with column weight three whose corresponding Tanner graph is free of certain ETSs.
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dryriver writes: We live in a time where mainstream media, websites, blogs, social media accounts, your barely computer literate next door neighbor and so forth frequently rave about the "innovation" that is happening everywhere. But as someone who experienced developments in technology back in the 1980s and 1990s, in computing in particular, I cannot shake the feeling that, somehow, the "deep nerds" who were innovating back then did it better and with more heartfelt passion than I can feel today. Of course, tech from 30 years ago seems a bit primitive compared to today  computer gear is faster and sleeker nowadays. But it seems that the core techniques and core concepts used in much of what is called "innovation" today were invented for the first time oneaftertheother back then, and going back as far as the 1950s maybe. I get the impression that much of what makes billions in profits today and wows everyone is mere improvements on what was actually invented and trail blazed for t
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As multiagent networks grow in size and scale, they become increasingly difficult to synchronize, though agents must work together even when generating and sharing different information at different times. Targeting such cases, this paper presents an asynchronous optimization framework in which the time between successive communications and computations is unknown and unspecified for each agent. Agents' updates are carried out in blocks, with each agent updating only a small subset of all decision variables. Each agent uses an independently chosen Tikhonov regularization, and convergence is measured with respect to a weighted blockmaximum norm in which agents' blocks can be measured in different pnorms and weighted differently to normalize problems. Asymptotic convergence is shown and convergence rates are derived explicitly in terms of a problem's parameters, with only mild restrictions on what they can be. Simulation results are included to verify the theoretical developments made
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We consider random polynomials of the form $H_n(z)=\sum_{j=0}^n\xi_jq_j(z)$ where the $\{\xi_j\}$ are i.i.d nondegenerate complex random variables, and the $\{q_j(z)\}$ are orthonormal polynomials with respect to a compactly supported measure $\tau$ satisfying the BernsteinMarkov property on a regular compact set $K \subset \mathbb{C}$. We show that if $\mathbb{P}(\xi_0>e^{z})=o(z^{1})$, then the normalized counting measure of the zeros of $H_n$ converges weakly in probability to the equilibrium measure of $K.$ This is the best possible result, in the sense that the roots of $G_n(z)=\sum_{j=0}^n\xi_jz^j$ fail to converge in probability to the appropriate equilibrium measure when the above condition on the $\xi_j$ is not satisfied. In addition, we give a multivariable version of this result. We also consider random polynomials of the form $\sum_{k=0}^n\xi_kf_{n,k}z^k$, where the coefficients $f_{n,k}$ are complex constants satisfying certain conditions, and the random variab
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Assume that we embed the path $P_n$ as a subgraph of a $2$dimensional grid, namely, $P_k \times P_l$. Given such an embedding, we consider the ordered set of subpaths $L_1, L_2, \ldots , L_m$ which are maximal straight segments in the embedding, and such that the end of $L_i$ is the beginning of $L_{i+1}$. Suppose that $L_i\cong P_2$, for some $i$ and that some vertex $u$ of $L_{i1}$ is at distance $1$ in the grid to a vertex $v$ of $L_{i+1}$. An elementary transformation of the path consists in replacing the edge of $L_i$ by a new edge $uv$. A tree $T$ of order $n$ is said to be a pathlike tree, when it can be obtained from some embedding of $P_n$ in the $2$dimensional grid, by a sequence of elementary transformations. Thus, the maximum degree of a pathlike tree is at most $4$. Intuitively speaking, a tree admits a linear configuration if it can be described by a sequence of paths in such a way that only vertices from two consecutive paths, which are at the same distance of the e
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We demonstrate a method of associating the principal symbol at a $K$point with a linear differential operator acting between modules over a commutative algebra, and we use it to define the ellipticity of a linear differential operator in a purely algebraic way. We prove that the ellipticity is preserved by a surjective homomorphism of algebras. As an example, we show that for every real affine variety there is an elliptic linear differential operator acting on the algebra of regular functions on this variety.
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Despite its numerical challenges, finite element method is used to compute viscous fluid flow. A consensus on the cause of numerical problems has been reached; however, general algorithmsallowing a robust and accurate simulation for any processare still missing. Either a very high computational cost is necessary for a direct numerical solution (DNS) or some limiting procedure is used by adding artificial dissipation to the system. These stabilization methods are often applied relative to the element size such that a local monotonous convergence cannot be observed. We need a computational strategy for solving viscous fluid flow using only the balance equations. In this work, we present a general procedure solving fluid mechanics problems without use of any stabilization or splitting schemes. Hence its generalization to multiphysics applications is straightforward. We discuss several numerical problems and present the methodology rigorously. Implementation is achieved by using ope
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We introduce the oriented BrauerClifford and degenerate affine oriented BrauerClifford supercategories. These are diagrammatically defined monoidal supercategories which provide combinatorial models for certain natural monoidal supercategories of supermodules and endosuperfunctors, respectively, for the Lie superalgebras of type Q. Our main results are basis theorems for these diagram supercategories. We also discuss connections and applications to the representation theory of the Lie superalgebra of type Q.
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An anonymous reader quotes a report from Ars Technica: A federal judge has revived a lawsuit that angry customers filed against AT&T over the company's throttling of unlimited mobile data plans. The decision comes two years after the same judge decided that customers could only have their complaints heard individually in arbitration instead of in a classaction lawsuit. The 2016 ruling in AT&T's favor was affirmed by a federal appeals court. But the customers subsequently filed a motion to reconsider the arbitration decision, saying that an April 2017 decision by the California Supreme Court "constitutes a change in law occurring after the Courts arbitration order," Judge Edward Chen of U.S. District Court for the Northern District of California said in the new ruling issued last week. The state Supreme Court "held that an arbitration agreement that waives the right to seek the statutory remedy of public injunctive relief in any forum is contrary to California public policy and
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An anonymous reader writes: Hi fellow readers. I don't recall reading many comic books as a kid (mostly because I could not afford them), but of late, I have been considering giving that a shot. I wanted to ask if you had any tips to share. Do I start with paperback editions, or do I jump directly into digital? Also, could you recommend a few good scific comic book series? Thanks in advance!
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Secure message dissemination is an important issue in vehicular networks, especially considering the vulnerability of vehicle to vehicle message dissemination to malicious attacks. Traditional security mechanisms, largely based on message encryption and key management, can only guarantee secure message exchanges between known source and destination pairs. In vehicular networks however, every vehicle may learn its surrounding environment and contributes as a source, while in the meantime act as a destination or a relay of information from other vehicles, message exchanges often occur between "stranger" vehicles. For secure message dissemination in vehicular networks against insider attackers, who may tamper the content of the disseminated messages, ensuring the consistency and integrity of the transmitted messages becomes a major concern that traditional message encryption and key management based approaches fall short to provide. In this paper, by incorporating the underlying network t
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In this paper, we study the effects of the variations of the propagation delay over largescale antennaarrays used in massive multipleinput multipleoutput (MIMO) wideband communication systems on the statistical properties of the channel. Due to its simplicity and popularity, the Elliptical geometrybased stochastic channel model (GBSM) is employed to demonstrate new nonstationary properties of the channel in the frequency and spatial domains caused by the drift of delays. In addition, we show that the time of travel of multipath components (MPCs) over largescale arrays may result in overlooked frequency and spatial decorrelation effects. These are theoretically demonstrated by deriving the spacetimefrequency correlation functions (STFCFs) of both narrowband and wideband Elliptical models. Closedform expressions of the arrayvariant frequency correlation function (FCF), power delay profile (PDP), mean delay, and delay spread of single and multiconfocal Elliptical models are
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This is an expository plus research paper which mainly exposes preliminary connection and contrast between classical complex dynamics and semigroup dynamics of holomorphic functions. Classically, we expose some existing results of rational and transcendental dynamics and we see how far these results generalized to holomorphic semigroup dynamics as well as we also see what new phenomena occur.
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Hybrid dynamical systems have proven to be a powerful modeling abstraction, yet fundamental questions regarding their dynamical properties remain. In this paper, we develop a novel solution concept for a class of hybrid systems, which is a generalization of Filippov's solution concept. In the mathematical theory, these \emph{hybrid Filippov solutions} eliminate the notion of Zeno executions. Building on previous techniques for relaxing hybrid systems, we then introduce a family of smooth control systems that are used to approximate this solution concept. The trajectories of these relaxations vary differentiably with respect to initial conditions and inputs, may be numerically approximated using existing techniques, and are shown to converge to the hybrid Filippov solution in the limit. Finally, we outline how the results of this paper provide a foundation for future work to control hybrid systems using wellestablished techniques from Control Theory.
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Deregulated energy markets, demand forecasting, and the continuously increasing share of renewable energy sources callamong othersfor a structured consideration of uncertainties in optimal power flow problems. The main challenge is to guarantee power balance while maintaining economic and secure operation. In the presence of Gaussian uncertainties affine feedback policies are known to be viable options for this task. The present paper advocates a general framework for chanceconstrained OPF problems in terms of continuous random variables. It is shown that, irrespective of the type of distribution, the randomvariable minimizers lead to affine feedback policies. Introducing a threestep methodology that exploits polynomial chaos expansion, the present paper provides a constructive approach to chanceconstrained optimal power flow problems that does not assume a specific distribution, e.g. Gaussian, for the uncertainties. We illustrate our findings by means of a tutorial example.
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Considering a compact Riemann surface of genus greater than two, a Higgs~bundle is a pair composed of a holomorphic bundle over the Riemann surface, joint with an auxiliar vector field, socalled Higgs field. This theory started around thirty years ago, with Hitchin's work, when he reduced the selfduality equations from dimension four to dimension two, and so, studied those equations over Riemann surfaces. Hitchin baptized those fields as "Higgs fields" beacuse in the context of physics and gauge theory, they describe similar particles to those described by the Higgs bosson. Later, Simpson used the name "Higgs bundle" for a holomorphic bundle together with a Higgs field. Today, Higgs bundles are the subject of research in several areas such as nonabelian Hodge theory, Langlands, mirror symmetry, integrable systems, quantum field theory (QFT), among others. The main purposes here are to introduce these objects, and to present a brief construction of the moduli space of Higgs bundles.
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The Suslin hypothesis states that there are no nonseparable complete dense linear orderings without endpoints which have the countable chain condition. $\mathsf{ZF + AD^+ + V = L(\mathscr{P}(\mathbb{R}))}$ proves the Suslin hypothesis. In particular, if $L(\mathbb{R}) \models \mathsf{AD}$, then $L(\mathbb{R})$ satisfies the Suslin hypothesis, which answers a question of Foreman.
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In Menlo Park, Calif., Facebook is building a real community and testing the proposition: Do people love tech companies so much they will live inside them? From a report: Willow Village will be wedged between the Menlo Park neighborhood of Belle Haven and the city of East Palo Alto, both heavily Hispanic communities that are among Silicon Valley's poorest. Facebook is planning 1,500 apartments, and has agreed with Menlo Park to offer 225 of them at belowmarket rates. The most likely tenants of the fullprice units are Facebook employees, who already receive a fivefigure bonus if they live near the office. The community will have eight acres of parks, plazas and bikepedestrian paths open to the public. Facebook wants to revitalize the railway running alongside the property and will finish next year a pedestrian bridge over the expressway. The bridge will provide access to the trail that rings San Francisco Bay, a boon for birders and bikers. Mr. Tenanes, Facebook's vice president for
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In our previous study of duality for complete discrete valuation fields with perfect residue field, we treated coefficients in finite flat group schemes. In this paper, we treat abelian varieties. This in particular implies Grothendieck's conjecture on the perfectness of his pairing between the Neron component groups of an abelian variety and its dual. The point is that our formulation is wellsuited with Galois descent. From the known case of semistable abelian varieties, we deduce the perfectness in full generality. We also treat coefficients in tori and, more generally, 1motives.
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The main purpose of this paper is to find the fixed point in such cases where existing literature remain silent. In this paper we introduce partial completeness, a new type of contraction and many other definitions. Using this approach the existence of fixed point can be proved in incomplete metric spaces with noncontraction map on it. We have reported an example in support our result.
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Ant Colony System (ACS) is a distributed (agent based) algorithm which has been widely studied on the Symmetric Travelling Salesman Problem (TSP). The optimum parameters for this algorithm have to be found by trial and error. We use a Particle Swarm Optimization algorithm (PSO) to optimize the ACS parameters working in a designed subset of TSP instances. First goal is to perform the hybrid PSOACS algorithm on a single instance to find the optimum parameters and optimum solutions for the instance. Second goal is to analyze those sets of optimum parameters, in relation to instance characteristics. Computational results have shown good quality solutions for single instances though with high computational times, and that there may be sets of parameters that work optimally for a majority of instances.
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We extend analytic large network results on default contagion in random graphs to capture a pronounced Block Model structure. This includes as a special case the CorePeriphery network structure, which plays a prominent role in recent research on systemic risk. Further, in the existing literature on systemic risk using random graph methods the problematic assumption that the distribution of liabilities solely depends on the creditor type seems to persist. Under this assumption a straightforward application of the law of large numbers allows to turn edge related random elements into deterministic vertex properties. Here we study a general setting in which the liabilities may depend on both the creditor and the debtor where this argument breaks down and a direct asymptotic analysis of the edge weighted random graph becomes necessary. Among several other applications our results allow us to obtain resilience conditions for the entire network (for example the global financial network) base
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The Zap Qlearning algorithm introduced in this paper is an improvement of Watkins' original algorithm and recent competitors in several respects. It is a matrixgain algorithm designed so that its asymptotic variance is optimal. Moreover, an ODE analysis suggests that the transient behavior is a close match to a deterministic NewtonRaphson implementation. This is made possible by a two timescale update equation for the matrix gain sequence. The analysis suggests that the approach will lead to stable and efficient computation even for nonideal parameterized settings. Numerical experiments confirm the quick convergence, even in such nonideal cases. A secondary goal of this paper is tutorial. The first half of the paper contains a survey on reinforcement learning algorithms, with a focus on minimum variance algorithms.
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Piecewise deterministic Markov processes (PDMPs) have recently been used for efficient Bayesian analysis of big data, estimation of Boltzmann distributions in molecular dynamics (MD), and hybrid modeling of chemical reaction networks. Such PDMPscan be metastable, considerablyslowing the convergence of sampling. We propose overcoming this obstacle with the parallel replica dynamics (ParRep), which were originally designed to accelerate stochastic MD and more recently have been used to speed up stationary averaging in chemical reaction networks. We show how to use ParRep to accelerate dynamics and stationary computations for PDMPs in the presence of metastability. We present algorithms for synchronous and asynchronous computing environments, and rigorously justify consistency in both settings using a trajectory fragment framework. Since continuous time Markov chains, including reaction network models, are a special case of PDMPs, our results also apply in that setting. Our framework show
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This is the first in a series of three notes on an investigation into core regular double Stone algebras, CRDSA, and are meant to be read in order. They were born out of a model of network security where individual nodes are considered to be in one of 3 states. Applications of these results are being explored, results of at least one of which will be published at a later date. The two notes following this will establish a duality between the category of CRDSA and specifically crafted bitopological spaces. Let J be any nonempty set of network nodes, not necessarily finite. We denote the node set bounded distributive lattice through the pairwise disjoint subsets of J with the well known binary operations of ternary set partitions and note J = 1 is our minimal case. We then show the resultant bounded distributive lattice is isomorphic to direct products of the 3 element chain, C_3. We then derive that every CRDSA is a subdirect product of C_3. We use these results along with a few known
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We study the wave equation in an interval with two linearly moving endpoints. We give the exact solution by a series formula, then we show that the energy of the solution decay at the rate $1/t$. We also establish observability results, at one or two endpoints, in a sharp time. Moreover, using the Hilbert uniqueness method, we derive exact boundary controllability results.
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