81 research outputs found
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Maintaining Coherency of Dynamic Data in Cooperating Repositories
In this paper, we consider techniques for disseminating dynamic data—such as stock prices and real-time weather information—from sources to a set of repositories. We focus on the problem of maintaining coherency of dynamic data items in a network of cooperating repositories. We show that cooperation among repositories— where each repository pushes updates of data items to other repositories—helps reduce system-wide communication and computation overheads for coherency maintenance. However, contrary to intuition, we also show that increasing the degree of cooperation beyond a certain point can, in fact, be detrimental to the goal of maintaining coherency at low communication and computational overheads. We present techniques (i) to derive the “optimal” degree of cooperation among repositories, (ii) to construct an efficient dissemination tree for propagating changes from sources to cooperating repositories, and (iii) to determine when to push an update from one repository to another for coherency maintenance. We evaluate the efficacy of our techniques using real-world traces of dynamically changing data items (specifically, stock prices) and show that careful dissemination of updates through a network of cooperating repositories can substantially lower the cost of coherency maintenance
Skolem Functions for Factored Formulas
Given a propositional formula F(x,y), a Skolem function for x is a function
\Psi(y), such that substituting \Psi(y) for x in F gives a formula semantically
equivalent to \exists F. Automatically generating Skolem functions is of
significant interest in several applications including certified QBF solving,
finding strategies of players in games, synthesising circuits and bit-vector
programs from specifications, disjunctive decomposition of sequential circuits
etc. In many such applications, F is given as a conjunction of factors, each of
which depends on a small subset of variables. Existing algorithms for Skolem
function generation ignore any such factored form and treat F as a monolithic
function. This presents scalability hurdles in medium to large problem
instances. In this paper, we argue that exploiting the factored form of F can
give significant performance improvements in practice when computing Skolem
functions. We present a new CEGAR style algorithm for generating Skolem
functions from factored propositional formulas. In contrast to earlier work,
our algorithm neither requires a proof of QBF satisfiability nor uses
composition of monolithic conjunctions of factors. We show experimentally that
our algorithm generates smaller Skolem functions and outperforms
state-of-the-art approaches on several large benchmarks.Comment: Full version of FMCAD 2015 conference publicatio
Balancing Parental Needs for Physicians\u27 Technical Help With Physicians\u27 Legal Protection
Band Aids for Medicaid: Preserving the High Numbers of Child Health Coverage During the Pandemic
Respiratory syncytial virus as a cause of pulmonary hemorrhage in a low birth weight infant - strategies for protection and prevention: a case report
Going Farther by Going Together: Collaboration as a Tool in Advocacy
With greater understanding of the impact of social determinants on child health, advocacy has become essential to promoting children\u27s health, particularly at the population level. Successful advocacy requires coalition building. Steps on how to create a productive coalition, including the selection of partner organizations, understanding how these groups enhance your activities, and strict definition of assigned roles is reviewed. Examples of successful coalitions are reviewed. A list of potential partners, who focus on various aspects of child health, is provided
Clinical Studies and Quantitative Descriptors of Corneal Architecture and Topography Following Excimer Laser Photorefractive Keratectomy for Correction of Myopia
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