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Just-In-Time Constraint-Based Inference for Qualitative Spatial and Temporal Reasoning

KUNSTLICHE INTELLIGENZ 2020年第2期34卷 259-270页

作者： Sioutis, Michael Univ Bamberg Fac Informat Syst & Appl Comp Sci Weberei 5 D-96047 Bamberg Germany

We discuss a research roadmap for going beyond the state of the art in qualitative spatial and temporal reasoning (QSTR). Simply put, QSTR is a major field of study in Artificial Intelligence that abstracts from numerical quantities of space and time by using qualitative descriptions instead (e.g., precedes, contains, is left of);thus, it provides a concise framework that allows for rather inexpensive reasoning about entities located in space or time. Applications of QSTR can be found in a plethora of areas and domains such as smart environments, intelligent vehicles, and unmanned aircraft systems. Our discussion involves researching novel local consistencies in the aforementioned discipline, defining dynamic algorithms pertaining to these consistencies that can allow for efficient reasoning over changing spatio-temporal information, and leveraging the structures of the locally consistent related problems with regard to novel decomposability and theoretical tractability properties. Ultimately, we argue for pushing the envelope in QSTR via defining tools for tackling dynamic variants of the fundamental reasoning problems in this discipline, i.e., problems stated in terms of changing input data. Indeed, time is a continuous flow and spatial objects can change (e.g., in shape, size, or structure) as time passes;therefore, it is pertinent to be able to efficiently reason about dynamic spatio-temporal data. Finally, these tools are to be integrated into the larger context of highly active areas such as neuro-symbolic learning and reasoning, planning, data mining, and robotic applications. Our final goal is to inspire further discussion in the community about constraint-based QSTR in general, and the possible lines of future research that we outline here in particular.

关键词： Qualitative constraints Spatio-temporal reasoning Just-in-time inference Local consistencies Singleton checks dynamic algorithms Decomposability Adaptivity Parallelization

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Big data algorithms beyond machine learning

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KUNSTLICHE INTELLIGENZ 2018年第1期32卷 9-17页

作者： Mnich, Matthias Maastricht Univ Dept Quantitat Econ POB 616 NL-6200 MD Maastricht Netherlands Univ Bonn Inst Informat Friedrich Ebert Allee 144 D-53113 Bonn Germany

The availability of big data sets in research, industry and society in general has opened up many possibilities of how to use this data. In many applications, however, it is not the data itself that is of interest but rather we want to answer some question about it. These answers may sometimes be phrased as solutions to an optimization problem. We survey some algorithmic methods that optimize over large-scale data sets, beyond the realm of machine learning.

关键词： Big data algorithms Large-scale optimization Kernelization dynamic algorithms

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Impact of condition number on total sum rate for NOMA systems

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ELECTRONICS LETTERS 2020年第20期56卷 1091-+页

作者： Vidal-Beltran, S. Lopez-Bonilla, J. L. Martinez-Pinon, F. Cuenca-Alvarez, R. Inst Politecn Nacl Escuela Super Ingn Mecan & Elect Zacatenco Mexico City DF Mexico Inst Politecn Nacl Ctr Invest & Innovac Tecnol Azcapotzalco Mexico City DF Mexico

In the fifth-generation mobile communications networks, several resource allocation techniques have been used, such as static allocation and dynamic algorithms (greedy or matching theory);this work proposes a new subcarrier allocation scheme based on the evaluation of the instantaneous behaviour of the wireless channel using the condition number of the channel matrix H. Simulation results reveal that the proposed scheme increases the total sum rate of the system, compared to their predecessors.

关键词： wireless channels resource allocation 5G mobile communication multi-access systems greedy algorithms matrix algebra NOMA systems fifth-generation mobile communications networks resource allocation techniques static allocation dynamic algorithms greedy theory matching theory subcarrier allocation scheme instantaneous behaviour wireless channel channel matrix condition number impact

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dynamically switching vertices in planar graphs

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ALGORITHMICA 2000年第1期28卷 76-103页

作者： Frigioni, D Italiano, GF Univ Roma La Sapienza Dipartimento Informat & Sistemist I-00198 Rome Italy Max Planck Inst Informat D-66123 Saarbrucken Germany Univ Aquila Dipartimento Ingn Elettr I-67040 Laquila Italy Univ Roma Tor Vergata Dipartimento Sistemi & Prod Rome Italy

We consider graphs whose vertices may be in one of two different states: either on or off. We wish to maintain dynamically such graphs under an intermixed sequence of updates and queries. An update may reverse the status of a vertex, by switching it either on or off, and may insert a new edge or delete an existing edge. A query tests whether any two given vertices are connected in the subgraph induced by the vertices that are on. We give efficient algorithms that maintain information about connectivity on planar graphs in O(log(3) n) amortized time per query, insert, delete, switch-on, and switch-off operation over sequences of at least Omega(n) operations, where n is the number of vertices of the graph.

关键词： planar graphs dynamic algorithms connectivity separators

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Two methods for the generation of chordal graphs

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ANNALS OF OPERATIONS RESEARCH 2008年第1期157卷 47-60页

作者： Markenzon, Lilian Vernet, Oswaldo Araujo, Luiz Henrique Univ Fed Rio de Janeiro Nucl Comp Elect Rio De Janeiro Brazil Inst Militar Engn Rio De Janeiro Brazil

In this paper two methods for automatic generation of connected chordal graphs are proposed: the first one is based on new results concerning the dynamic maintenance of chordality under edge insertions;the second is based on expansion/merging of maximal cliques. Theoretical and experimental results are presented. In both methods, chordality is preserved along the whole generation process.

关键词： chordal graphs dynamic algorithms clique-tree graph generation

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Ensemble-based methods for describing protein dynamics

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CURRENT OPINION IN PHARMACOLOGY 2010年第6期10卷 760-769页

作者： Jacobs, Donald J. Univ N Carolina Dept Phys & Opt Sci Charlotte NC 28223 USA

Molecular dynamics (MD) simulation is a natural approach for studying protein dynamics, and coupled with the ideas of multiscale modeling, MD proves to be the gold standard in computational biology to investigate mechanistic details related to protein function In principle if MD trajectories are long enough, the ensemble of protein conformations generated allows thermodynamic and kinetic properties to be predicted We know from experiments that proteins exhibit a high degree of fidelity in function and that empirical kinetic models are successful in describing kinetics suggesting that the ensemble of conformations cluster into well-defined thermodynamic states, which are frequently metastable The experimental evidence suggest that more efficient computational models that retain only essential properties of the protein can be constructed to faithfully reproduce the relatively few observed thermodynamic states, and perhaps describe transition states if the model is sufficiently detailed Indeed, there are many so-called ensemble-based methods that attempt to generate more complete ensembles than MD can provide by focusing on the most important driving forces through simplified representations of how elements within the protein interact Although coarse-graining is employed in MD and other approaches, such as in elastic network models, the key distinguishing factor of ensemble-based methods is that they are meant to efficiently generate a large ensemble of conformations without solving explicit equations of motion This review highlights three types of ensemble-based methods illustrated by COREX and the Wako-Saito-Munoz-Eaton (WSME) model the Framework Rigidity Optimized dynamic Algorithm (FRODA) and the distance constraint model (DCM)

关键词： Protein Conformation Computational Biology protein structure function Ensembles Thermodynamics Kinetics Equations of motion dynamic algorithms Protein DRIVING FORCE Bioinformatics

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MAINTAINING SHORTEST PATHS UNDER DELETIONS IN WEIGHTED DIRECTED GRAPHS

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SIAM JOURNAL ON COMPUTING 2016年第2期45卷 548-574页

作者： Bernstein, Aaron Columbia Univ Dept Comp Sci New York NY 10027 USA

We present an improved algorithm for maintaining all-pairs (1 + epsilon) approximate shortest paths under deletions and weight-increases. The previous state of the art for this problem is total update time (O) over tilde (n(2)root m/epsilon) over all updates for directed unweighted graphs [ S. Baswana, R. Hariharan, and S. Sen, J. algorithms, 62 (2007), pp. 74-92], and (O) over tilde (mn/epsilon) for undirected unweighted graphs [ L. Roditty and U. Zwick, in Proceedings of the 45th FOCS, Rome, Italy, 2004, pp. 499-508]. Both algorithms are randomized and have constant query time. Very recently, Henzinger, Krinninger, and Nanongkai presented a deterministic version of the latter algorithm [ M. Henzinger, S. Krinninger, and D. Nanongkai, in IEEE FOCS, 2013, pp. 538-547]. Note that (O) over tilde (mn) is a natural barrier because even with a (1 + epsilon) approximation, there is no o(mn) combinatorial algorithm for the static all-pairs shortest path problem. Our algorithm works on directed weighted graphs and has total (randomized) update time (O) over tilde (mn log R/epsilon) where R is the ratio of the largest edge weight to appear at any point in the update sequence to the smallest such weight. (As with previous algorithms, our query time is constant.) Technically, the running time is (O) over tilde (mn log R/epsilon) + O(Delta), where Delta is the total number of updates;the same O(Delta) term is also implicitly present in all other algorithms for the problem, since a constant time per update is clearly unavoidable. Note that log R = O(log(n)) as long as weights are polynomial in n;thus, we effectively expand the (O) over tilde (mn/epsilon) total update time bound from undirected unweighted graphs to directed graphs with polynomial weights. This is in fact the first nontrivial algorithm for decremental all-pairs shortest paths that works on weighted graphs (previous algorithms could only handle small integer weights). By a well-known reduction from decremental algo

关键词： graph algorithms dynamic algorithms approximation shortest paths

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dynamic fuzzy neighborhood rough set approach for interval-valued information systems with fuzzy decision

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APPLIED SOFT COMPUTING 2021年 111卷 107679-107679页

作者： Yang, Lei Qin, Keyun Sang, Binbin Xu, Weihua Southwest Jiaotong Univ Sch Math Chengdu 611756 Peoples R China Southwest Jiaotong Univ Sch Comp & Artificial Intelligence Chengdu 611756 Peoples R China Southwest Univ Coll Artificial Intelligence Chongqing 400715 Peoples R China

Nowadays, many extended rough set models are proposed to acquire valuable knowledge from interval-valued information system. These existing models mainly focus on different forms of similarity relations. However, most of these similarity relations are qualitative rather than quantitative, which is not reasonable in some practical cases. In addition, with the arrival of new objects and the removal of obsolete objects, the interval-valued information system with fuzzy decision (IvIS_FD) is always changing with time. Therefore, how to efficiently mining knowledge from dynamic IvIS_FD is a meaningful topic. Motivated by these two issues, we study the dynamic fuzzy neighborhood rough set approach for IvIS_FD, aiming to effectively update the rough approximations when the IvIS_FD evolves over time. Firstly, delta-fuzzy neighborhood relation is defined to describe the similarity relation between objects quantitatively. Secondly, we introduce a novel fuzzy neighborhood rough set model and its matrix representation suitable for IvIS_FD. On this basis, we discuss the incremental mechanisms to update fuzzy neighborhood approximations when multiple objects are added to or deleted from an IvIS_FD, respectively. Meanwhile, corresponding dynamic algorithms are designed and explained. Finally, experiments are performed on nine public data sets to evaluate the performance of the dynamic fuzzy neighborhood rough set model. Experimental results verify that the proposed model is effective and efficient for updating rough approximations in dynamic IvIS_FD. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Interval-valued information system with fuzzy decision delta-fuzzy neighborhood relation Fuzzy neighborhood rough set Incremental mechanisms dynamic algorithms

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A Novel dynamic Algorithm for IT Outsourcing Risk Assessment Based on Transaction Cost Theory

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DISCRETE dynamicS IN NATURE AND SOCIETY 2015年第Pt.1期2015卷 10-10页

作者： Cong, Guodong Chen, Tinggui Zhejiang Gongshang Univ Sch Tourism & City Adm Hangzhou 311018 Zhejiang Peoples R China Zhejiang Gongshang Univ Coll Comp Sci & Informat Engn Hangzhou 311018 Zhejiang Peoples R China

With the great risk exposed in IT outsourcing, how to assess IT outsourcing risk becomes a critical issue. However, most of approaches to date need to further adapt to the particular complexity of IT outsourcing risk for either falling short in subjective bias, inaccuracy, or efficiency. This paper proposes a dynamic algorithm of risk assessment. It initially forwards extended three layers (risk factors, risks, and risk consequences) of transferring mechanism based on transaction cost theory (TCT) as the framework of risk analysis, which bridges the interconnection of components in three layers with preset transferring probability and impact. Then, it establishes an equation group between risk factors and risk consequences, which assures the "attribution" more precisely to track the specific sources that lead to certain loss. Namely, in each phase of the outsourcing lifecycle, both the likelihood and the loss of each risk factor and those of each risk are acquired through solving equation group with real data of risk consequences collected. In this "reverse" way, risk assessment becomes a responsive and interactive process with real data instead of subjective estimation, which improves the accuracy and alleviates bias in risk assessment. The numerical case proves the effectiveness of the algorithm compared with the approach forwarded by other references.

关键词： observational data outsourcing Risk Factors transaction costs Risk Assessment Risk Management dynamic algorithms interactive processing information technology

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DISTRIBUTED APPROXIMATE MATCHING

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SIAM JOURNAL ON COMPUTING 2009年第2期39卷 445-460页

作者： Lotker, Zvi Patt-Shamir, Boaz Rosen, Adi Ben Gurion Univ Negev Dept Commun Syst Engn IL-84105 Beer Sheva Israel Tel Aviv Univ Dept Elect Engn IL-69978 Tel Aviv Israel Univ Paris 11 LRI F-91405 Orsay France CNRS F-91405 Orsay France

We consider distributed algorithms for approximate maximum matching on general graphs. Our main result is a randomized (4 + epsilon)-approximation distributed algorithm for maximum weighted matching, whose running time is O(log n) for any constant epsilon > 0, where n is the number of nodes in the graph. This is, to the best of our knowledge, the first log-time distributed algorithm that achieves constant approximation for maximum weighted matching on general graphs. In addition, we consider the dynamic case, where nodes are inserted and deleted one at a time. For unweighted dynamic graphs, we give a distributed algorithm that maintains a (1 + epsilon)-approximation in O(1/epsilon) time for each node insertion or deletion for any constant epsilon > 0. For weighted dynamic graphs we give a constant-factor approximation distributed algorithm that runs in constant time for each insertion or deletion.

关键词： graph algorithms distributed algorithms maximum matching dynamic algorithms distributed approximation algorithms

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