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91.
Partitioning large networks without breaking communities 总被引:1,自引:1,他引:0
Anand Narasimhamurthy Derek Greene Neil Hurley Pádraig Cunningham 《Knowledge and Information Systems》2010,25(2):345-369
The identification of cohesive communities is a key process in social network analysis. However, the algorithms that are effective
for finding communities do not scale well to very large problems, as their time complexity is worse than linear in the number
of edges in the graph. This is an important issue for those interested in applying social network analysis techniques to very
large networks, such as networks of mobile phone subscribers. In this respect, the contributions of this paper are twofold.
First, we demonstrate these scaling issues using a prominent community-finding algorithm as a case study. Then, we show that
a two-stage process, whereby the network is first decomposed into manageable subnetworks using a multilevel graph partitioning
procedure, is effective in finding communities in networks with more than 106 nodes. 相似文献
92.
Efficient monitoring of parametric context-free patterns 总被引:1,自引:0,他引:1
Patrick O’Neil Meredith Dongyun Jin Feng Chen Grigore Roşu 《Automated Software Engineering》2010,17(2):149-180
Recent developments in runtime verification and monitoring show that parametric regular and temporal logic specifications
can be efficiently monitored against large programs. However, these logics reduce to ordinary finite automata, limiting their
expressivity. For example, neither can specify structured properties that refer to the call stack of the program. While context-free
grammars (CFGs) are expressive and well-understood, existing techniques for monitoring CFGs generate large runtime overhead
in real-life applications. This paper demonstrates that monitoring parametric CFGs is practical (with overhead on the order of 12% or lower in most cases). We present a monitor synthesis algorithm for CFGs based on an
LR(1) parsing algorithm, modified to account for good prefix matching. In addition, a logic-independent mechanism is introduced
to support matching against the suffixes of execution traces. 相似文献
93.
Intense competition in the UK charity fundraising market and the near continuous need for charities to acquire new supporters, reactivate lapsed donors and encourage first time donors to make further gifts has resulted in charities needing repeatedly to initiate novel fundraising campaigns. The starting point for an innovative campaign is an idea or set of ideas that will attract public attention, differentiate a charity from other fundraising organizations and distinguish the charity's current marketing activities from those undertaken in the past. An important but neglected issue in the charity idea creation field is the question of where and how fundraising organizations source their ideas for new campaigns. This empirical study identified (i) the main sources of fresh ideas for fundraising employed by a sample of 417 British charities, and (ii) certain antecedents of a charity's use of various categories of sources. Potential connections between particular types of idea source and managerial satisfaction with both the creative quality of the ideas obtained and the financial revenues derived from these ideas were also examined. 相似文献
94.
Neil D. Christensen 《Computer Physics Communications》2009,180(9):1614-1641
In this paper we present FeynRules, a new Mathematica package that facilitates the implementation of new particle physics models. After the user implements the basic model information (e.g., particle content, parameters and Lagrangian), FeynRules derives the Feynman rules and stores them in a generic form suitable for translation to any Feynman diagram calculation program. The model can then be translated to the format specific to a particular Feynman diagram calculator via FeynRules translation interfaces. Such interfaces have been written for CalcHEP/CompHEP, FeynArts/FormCalc, MadGraph/MadEvent and Sherpa, making it possible to write a new model once and have it work in all of these programs. In this paper, we describe how to implement a new model, generate the Feynman rules, use a generic translation interface, and write a new translation interface. We also discuss the details of the FeynRules code.
Program summary
Program title: FeynRulesCatalogue identifier: AEDI_v1_0Program summary URL::http://cpc.cs.qub.ac.uk/summaries/AEDI_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 15 980No. of bytes in distributed program, including test data, etc.: 137 383Distribution format: tar.gzProgramming language: MathematicaComputer: Platforms on which Mathematica is availableOperating system: Operating systems on which Mathematica is availableClassification: 11.1, 11.2, 11.6Nature of problem: Automatic derivation of Feynman rules from a Lagrangian. Implementation of new models into Monte Carlo event generators and FeynArts.Solution method: FeynRules works in two steps:1. derivation of the Feynman rules directly form the Lagrangian using canonical commutation relations among fields and creation operators. 2. implementation of the new physics model into FeynArts as well as various Monte Carlo programs via interfaces. - Full-size table
95.
Stefan Mairhofer James Johnson Craig J. Sturrock Malcolm J. Bennett Sacha J. Mooney Tony P. Pridmore 《Machine Vision and Applications》2016,27(5):721-734
We propose a visual object tracking framework for the extraction of multiple interacting plant root systems from three-dimensional X-ray micro computed tomography images of plants grown in soil. Our method is based on a level set framework guided by a greyscale intensity distribution model to identify object boundaries in image cross-sections. Root objects are followed through the data volume, while updating the tracker’s appearance models to adapt to changing intensity values. In the presence of multiple root systems, multiple trackers can be used, but need to distinguish target objects from one another in order to correctly associate roots with their originating plants. Since root objects are expected to exhibit similar greyscale intensity distributions, shape information is used to constrain the evolving level set interfaces in order to lock trackers to their correct targets. The proposed method is tested on root systems of wheat plants grown in soil. 相似文献
96.
Mehdi Dastani Leendert van der Torre Neil Yorke-Smith 《Autonomous Agents and Multi-Agent Systems》2017,31(2):207-249
In an organisational setting such as an online marketplace, an entity called the ‘organisation’ or ‘institution’ defines interaction protocols, monitors agent interaction, and intervenes to enforce the interaction protocols. The organisation might be a software system that thus regulates the marketplace, for example. In this article we abstract over application-specific protocols and consider commitment lifecycles as generic interaction protocols. We model interaction protocols by explicitly-represented norms, such that we can operationalise the enforcement of protocols by means of norm enforcement, and we can analyse the protocols by a logical analysis of the norms. We adopt insights and methods from commitment-based approaches to agent interaction as well as from norm-based approaches to agent behaviour governance. First, we show how to use explicitly-represented norms to model commitment dynamics (lifecycles). Second, we introduce an operational semantics to operationalise norm enforcement. Third, we show how to logically analyse interaction protocols by means of commitment dynamics and norm enforcement. The model, semantics, and analysis are illustrated by a running example from a vehicle insurance domain. 相似文献
97.
Constructing plans that can handle multiple problem instances is a longstanding open problem in AI. We present a framework for generalized planning that captures the notion of algorithm-like plans and unifies various approaches developed for addressing this problem. Using this framework, and building on the TVLA system for static analysis of programs, we develop a novel approach for computing generalizations of classical plans by identifying sequences of actions that will make measurable progress when placed in a loop. In a wide class of problems that we characterize formally in the paper, these methods allow us to find generalized plans with loops for solving problem instances of unbounded sizes and also to determine the correctness and applicability of the computed generalized plans. We demonstrate the scope and scalability of the proposed approach on a wide range of planning problems. 相似文献
98.
99.
Consider the robust network design problem of finding a minimum cost network with enough capacity to route all traffic demand
matrices in a given polytope. We investigate the impact of different routing models in this robust setting: in particular,
we compare oblivious routing, where the routing between each terminal pair must be fixed in advance, to dynamic routing, where routings may depend arbitrarily on the current demand. Our main result is a construction that shows that the
optimal cost of such a network based on oblivious routing (fractional or integral) may be a factor of Ω(log n) more than the cost required when using dynamic routing. This is true even in the important special case of the asymmetric
hose model. This answers a question in (Chekuri, SIGACT News 38(3):106–128, 2007), and is tight up to constant factors. Our proof technique builds on a connection between expander graphs and robust design
for single-sink traffic patterns (Chekuri et al., Networks 50(1):50–54, 2007). 相似文献
100.