443 research outputs found
A constraint-based framework for configuration
The research presented here aims at providing a comprehensive framework for solving configuration problems, based on the Constraint Satisfaction paradigm. This thesis is addressing the two main issues raised by a configuration task: modeling the problem and solving it efficiently. Our approach subsumes previous approaches, incorporating both Simplification and further extension, offering increased representational power and efficiency.
Modeling. We advance the idea of local, context independent models for the types of objects in the application domain, and show how the model of an artifact can be built as a composition of local models of the constituent parts. Our modeling technique integrates two mechanisms for dealing with complexity, namely composition and abstraction. Using concepts such as locality, aggregation and inheritance, it offers support and guidance as to the appropriate content and organization of the domain knowledge, thus making knowledge specification and representation less error prone, and knowledge maintenance much easier.
There are two specific aspects which make modeling configuration problems challenging: the complexity and heterogeneity of relations that must be expressed, manipulated and maintained, and the dynamic nature of the configuration process. We address these issues by introducing Composite Constraint Satisfaction Problems, a new, nonstandard class of problems which extends the classic Constraint Satisfaction paradigm.
Efficiency. For the purpose of the work presented here, we are only interested in providing a guaranteed optimal solution to a configuration problem. To achieve this goal, our research focused on two complementary directions.
The first one led to a powerful search algorithm called Maintaining Arc Consistency Extended (MACE). By maintaining arc consistency and taking advantage of the problem structure, MACE turned out to be one of the best general purpose CSP search algorithms to date.
The second research direction aimed at reducing the search effort involved in proving the optimality of the proposed solution by making use of information which is specific to individual configuration problems. By adding redundant specialized constraints, the algorithm improves dramatically the lower bound computation. Using abstraction through focusing only on relevant features allows the algorithm to take advantage of context-dependent interchangeability between component instances and discard equivalent solutions, involving the same cost as solutions that have already been explored
When Pull Turns to Shove: A Continuous-Time Model for Opinion Dynamics
Accurate modeling of opinion dynamics has the potential to help us understand
polarization and what makes effective political discourse possible or
impossible. Here, we use physics-based methods to model the evolution of
political opinions within a continuously distributed population. We utilize a
network-free system of determining political influence and a local-attraction,
distal-repulsion dynamic for reaction to perceived content. Our approach allows
for the incorporation of intergroup bias such that messages from trusted
in-group sources enjoy greater leeway than out-group ones. We are able to
extrapolate these nonlinear microscopic dynamics to macroscopic population
distributions by using probabilistic functions representing biased
environments. The framework we put forward can reproduce real-world political
distributions and experimentally observed dynamics, and is amenable to further
refinement as more data becomes available.Comment: Main text and appendices: 14 pages including references, with 11
figure
Modeling and analysis of systems with nonlinear functional dependence on random quantities
Many real-world systems exhibit noisy evolution; interpreting their
finite-time behavior as arising from continuous-time processes (in the It\^o or
Stratonovich sense) has led to significant success in modeling and analysis in
a variety of fields. Here we argue that a class of differential equations where
evolution depends nonlinearly on a random or effectively-random quantity may
exhibit finite-time stochastic behavior in line with an equivalent It\^o
process, which is of great utility for their numerical simulation and
theoretical analysis. We put forward a method for this conversion, develop an
equilibrium-moment relation for It\^o attractors, and show that this relation
holds for our example system. This work enables the theoretical and numerical
examination of a wide class of mathematical models which might otherwise be
oversimplified due to a lack of appropriate tools.Comment: 13 pages, 6 figure
Impact of Groundwater Flow on Permafrost Degradation and Transportation Infrastructure Stability
INE/AUTC 13.0
Application of (U-Th)/He thermochronometry as a geothermal exploration tool in extensional tectonic settings: the Wassuk Range, Hawthorne, Nevada
Navy Geothermal Program Office at China Lake, C
Visualising Infinity on a Mobile Device
This paper discusses how a Java 2 Micro Edition (J2ME) application may be developed to visualise a wide variety of differing fractal types on a mobile phone. A limited number of J2ME applications are available that are capable of generating the Mandelbrot Set. At present there are no J2ME applications capable of generating a multitude of fractal image types
Editorial: deep carbon science
SZ was supported by Australian Research Council grant IH130200012, a University of Sydney Robinson Fellowship, and Alfred P. Sloan grants G-2017-9997 and G-2018-11296.Publisher PDFPeer reviewe
Comparison of 10-year overall survival between patients with G1 and G2 grade Ta bladder tumors
To compare long-term overall survival (OS) in patients with G1 and G2 grade Ta bladder cancer after transurethral resection of bladder tumors (TURBTs). Secondary aim was to investigate clinical and pathologic prognostic factors for OS of Ta patients, except G3/high grade (HG). A total of 243 patients, retrospectively selected, with Ta nonmuscle invasive bladder cancer (NMIBC) underwent TURBT between January 2006 and December 2008 (median follow-up 109 months). Inclusion criteria were: Ta at first manifestation, G1 or G2 grade with no associated carcinoma in situ (CIS). Seventy-nine patients were excluded due to concomitant CIS (1), G3/HG tumors (47), and lost to follow-up (31). Ethical approval was obtained from the Ethical Committee of the Mures County Hospital. Statistical analysis was performed using STATA 11.0. Following inclusion criteria, 164 patients with primary G1 or G2 Ta tumors, were enrolled. Recurrence was observed in 26 (15.8%) and progression in 5 (3%) patients. Ten-year survival in G1 patients was 67.8% (CI 54.3-78.1) and in G2 patients 59% (CI 49-67.3) (P=.31). Univariable and multivariable logistic regression analysis underlined that advanced age at diagnosis (hazard ratio [HR] 1.10) and no Bacillus Calmette-Guerin (BCG) treatment (HR 0.24 and 0.29) were independent predictors for death at 10 years after diagnosis. Long-term analysis confirms that patients with well differentiated (G1) and moderately well differentiated (G2) Ta tumors have similar OS. A longer OS was even reported in those who underwent BCG adjuvant therapy
Mobile Message Passing using a Scatternet Framework
The Mobile Message Passing Interface is a library which implements MPI functionality on Bluetooth enabled mobile phones. It provides many of the functions available in MPI, including point-to-point and global communication. The main restriction of the library is that it was designed to work over Bluetooth piconets. Piconet based networks provide for a maximum of eight devices connected together simultaneously. This limits the libraries usefulness for parallel computing. A solution to solve this problem is presented that provides the same functionality as the original Mobile MPI library, but implemented over a Bluetooth scatternet. A scatternet may be defined as a number of piconets interconnected by common node(s). An outline of the scatternet design is explained and its major components discussed
Introducing LoCo, a Logic for Configuration Problems
In this paper we present the core of LoCo, a logic-based high-level
representation language for expressing configuration problems. LoCo shall allow
to model these problems in an intuitive and declarative way, the dynamic
aspects of configuration notwithstanding. Our logic enforces that
configurations contain only finitely many components and reasoning can be
reduced to the task of model construction.Comment: In Proceedings LoCoCo 2011, arXiv:1108.609
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