scholarly journals Exploiting Partial Assignments for Efficient Evaluation of Answer Set Programs with External Source Access

2018 ◽  
Vol 62 ◽  
pp. 665-727 ◽  
Author(s):  
Thomas Eiter ◽  
Tobias Kaminski ◽  
Christoph Redl ◽  
Antonius Weinzierl
Keyword(s):  
State Of The Art ◽  
Search Space ◽  
External Source ◽  
The State ◽  
Efficiency Gain ◽  
Model Search ◽  
Wide Range ◽  
Search Space Pruning ◽  
Answer Sets ◽  
Answer Set

Answer Set Programming (ASP) is a well-known declarative problem solving approach based on nonmonotonic logic programs, which has been successfully applied to a wide range of applications in artificial intelligence and beyond. To address the needs of modern applications, HEX-programs were introduced as an extension of ASP with external atoms for accessing information outside programs via an API style bi-directional interface mechanism. To evaluate such programs, conflict-driving learning algorithms for SAT and ASP solving have been extended in order to capture the semantics of external atoms. However, a drawback of the state-of-the-art approach is that external atoms are only evaluated under complete assignments (i.e., input to the external source) while in practice, their values often can be determined already based on partial assignments alone (i.e., from incomplete input to the external source). This prevents early backtracking in case of conflicts, and hinders more efficient evaluation of HEX-programs. We thus extend the notion of external atoms to allow for three-valued evaluation under partial assignments, while the two-valued semantics of the overall HEX-formalism remains unchanged. This paves the way for three enhancements: first, to evaluate external sources at any point during model search, which can trigger learning knowledge about the source behavior and/or early backtracking in the spirit of theory propagation in SAT modulo theories (SMT). Second, to optimize the knowledge learned in terms of so-called nogoods, which roughly speaking are impossible input-output configurations. Shrinking nogoods to their relevant input part leads to more effective search space pruning. And third, to make a necessary minimality check of candidate answer sets more efficient by exploiting early external evaluation calls. As this check usually accounts for a large share of the total runtime, optimization is here particularly important. We further present an experimental evaluation of an implementation of a novel HEX-algorithm that incorporates these enhancements using a benchmark suite. Our results demonstrate a clear efficiency gain over the state-of-the-art HEX-solver for the benchmarks, and provide insights regarding the most effective combinations of solver configurations.

scholarly journals Density Guarantee on Finding Multiple Subgraphs and Subtensors

2021 ◽  
Vol 15 (5) ◽  
pp. 1-32
Author(s):  
Quang-huy Duong ◽  
Heri Ramampiaro ◽  
Kjetil Nørvåg ◽  
Thu-lan Dam
Keyword(s):  
Lower Bound ◽  
State Of The Art ◽  
The State ◽  
The Other ◽  
Exact Methods ◽  
Practical Solution ◽  
Novel Approach ◽  
Wide Range ◽  
Real World Datasets ◽  
Tensor Data

Dense subregion (subgraph & subtensor) detection is a well-studied area, with a wide range of applications, and numerous efficient approaches and algorithms have been proposed. Approximation approaches are commonly used for detecting dense subregions due to the complexity of the exact methods. Existing algorithms are generally efficient for dense subtensor and subgraph detection, and can perform well in many applications. However, most of the existing works utilize the state-or-the-art greedy 2-approximation algorithm to capably provide solutions with a loose theoretical density guarantee. The main drawback of most of these algorithms is that they can estimate only one subtensor, or subgraph, at a time, with a low guarantee on its density. While some methods can, on the other hand, estimate multiple subtensors, they can give a guarantee on the density with respect to the input tensor for the first estimated subsensor only. We address these drawbacks by providing both theoretical and practical solution for estimating multiple dense subtensors in tensor data and giving a higher lower bound of the density. In particular, we guarantee and prove a higher bound of the lower-bound density of the estimated subgraph and subtensors. We also propose a novel approach to show that there are multiple dense subtensors with a guarantee on its density that is greater than the lower bound used in the state-of-the-art algorithms. We evaluate our approach with extensive experiments on several real-world datasets, which demonstrates its efficiency and feasibility.

The State of the Art of Rubber-Seal Technology

1987 ◽  
Vol 60 (3) ◽  
pp. 381-416 ◽  
Author(s):  
B. S. Nau
Keyword(s):  
State Of The Art ◽  
Test Procedure ◽  
Working Party ◽  
The State ◽  
Supporting Evidence ◽  
Wide Range ◽  
Lip Seals ◽  
Alternative Hypotheses ◽  
Series Of Experiments ◽  
Range Of Values

Abstract The understanding of the engineering fundamentals of rubber seals of all the various types has been developing gradually over the past two or three decades, but there is still much to understand, Tables V–VII summarize the state of the art. In the case of rubber-based gaskets, the field of high-temperature applications has scarcely been touched, although there are plans to initiate work in this area both in the U.S.A. at PVRC, and in the U.K., at BHRA. In the case of reciprocating rubber seals, a broad basis of theory and experiment has been developed, yet it still is not possible to design such a seal from first principles. Indeed, in a comparative series of experiments run recently on seals from a single batch, tested in different laboratories round the world to the same test procedure, under the aegis of an ISO working party, a very wide range of values was reported for leakage and friction. The explanation for this has still to be ascertained. In the case of rotary lip seals, theories and supporting evidence have been brought forward to support alternative hypotheses for lubrication and sealing mechanisms. None can be said to have become generally accepted, and it remains to crystallize a unified theory.

scholarly journals The Embeddedness of Social Sciences and Economics in Research on Resources

Resources ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 15
Author(s):  
Juan Uribe-Toril ◽  
José Luis Ruiz-Real ◽  
Jaime de Pablo Valenciano
Keyword(s):  
Social Sciences ◽  
State Of The Art ◽  
Local Development ◽  
The State ◽  
Special Issue ◽  
Continuous Review ◽  
The Past ◽  
Research Fields ◽  
Wide Range ◽  
Knowledge Area

Sustainability, local development, and ecology are keywords that cover a wide range of research fields in both experimental and social sciences. The transversal nature of this knowledge area creates synergies but also divergences, making a continuous review of the existing literature necessary in order to facilitate research. There has been an increasing number of articles that have analyzed trends in the literature and the state-of-the-art in many subjects. In this Special Issue of Resources, the most prestigious researchers analyzed the past and future of Social Sciences in Resources from an economic, social, and environmental perspective.

scholarly journals Particle Swarm Contour Search Algorithm

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 407 ◽  
Author(s):  
Dominik Weikert ◽  
Sebastian Mai ◽  
Sanaz Mostaghim
Keyword(s):  
Image Processing ◽  
Real World ◽  
State Of The Art ◽  
Search Algorithm ◽  
Particle Swarm ◽  
Search Space ◽  
Local Information ◽  
The State ◽  
Complete Knowledge ◽  
Real World Applications

In this article, we present a new algorithm called Particle Swarm Contour Search (PSCS)—a Particle Swarm Optimisation inspired algorithm to find object contours in 2D environments. Currently, most contour-finding algorithms are based on image processing and require a complete overview of the search space in which the contour is to be found. However, for real-world applications this would require a complete knowledge about the search space, which may not be always feasible or possible. The proposed algorithm removes this requirement and is only based on the local information of the particles to accurately identify a contour. Particles search for the contour of an object and then traverse alongside using their known information about positions in- and out-side of the object. Our experiments show that the proposed PSCS algorithm can deliver comparable results as the state-of-the-art.

scholarly journals The Seventh Answer Set Programming Competition: Design and Results

2019 ◽  
Vol 20 (2) ◽  
pp. 176-204 ◽  
Author(s):  
MARTIN GEBSER ◽  
MARCO MARATEA ◽  
FRANCESCO RICCA
Keyword(s):  
Knowledge Representation ◽  
Logic Programming ◽  
State Of The Art ◽  
Answer Set Programming ◽  
The State ◽  
International Conference ◽  
Knowledge Representation Language ◽  
Representation Language ◽  
The University ◽  
Answer Set

AbstractAnswer Set Programming (ASP) is a prominent knowledge representation language with roots in logic programming and non-monotonic reasoning. Biennial ASP competitions are organized in order to furnish challenging benchmark collections and assess the advancement of the state of the art in ASP solving. In this paper, we report on the design and results of the Seventh ASP Competition, jointly organized by the University of Calabria (Italy), the University of Genova (Italy), and the University of Potsdam (Germany), in affiliation with the 14th International Conference on Logic Programming and Non-Monotonic Reasoning (LPNMR 2017).

scholarly journals Hardware Trojans in Chips: A Survey for Detection and Prevention

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5165
Author(s):  
Chen Dong ◽  
Yi Xu ◽  
Ximeng Liu ◽  
Fan Zhang ◽  
Guorong He ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
State Of The Art ◽  
Academic Community ◽  
The State ◽  
Third Party ◽  
Hardware Trojans ◽  
Advantages And Disadvantages ◽  
Wide Range ◽  
Ip Cores ◽  
Comprehensive Classification

Diverse and wide-range applications of integrated circuits (ICs) and the development of Cyber Physical System (CPS), more and more third-party manufacturers are involved in the manufacturing of ICs. Unfortunately, like software, hardware can also be subjected to malicious attacks. Untrusted outsourced manufacturing tools and intellectual property (IP) cores may bring enormous risks from highly integrated. Attributed to this manufacturing model, the malicious circuits (known as Hardware Trojans, HTs) can be implanted during the most designing and manufacturing stages of the ICs, causing a change of functionality, leakage of information, even a denial of services (DoS), and so on. In this paper, a survey of HTs is presented, which shows the threatens of chips, and the state-of-the-art preventing and detecting techniques. Starting from the introduction of HT structures, the recent researches in the academic community about HTs is compiled and comprehensive classification of HTs is proposed. The state-of-the-art HT protection techniques with their advantages and disadvantages are further analyzed. Finally, the development trends in hardware security are highlighted.

scholarly journals Assuring the Machine Learning Lifecycle

2021 ◽  
Vol 54 (5) ◽  
pp. 1-39
Author(s):  
Rob Ashmore ◽  
Radu Calinescu ◽  
Colin Paterson
Keyword(s):  
Machine Learning ◽  
Iterative Process ◽  
State Of The Art ◽  
The State ◽  
Enabling Technology ◽  
Safety Critical ◽  
Wide Range ◽  
Comprehensive Survey ◽  
Intended Use

Machine learning has evolved into an enabling technology for a wide range of highly successful applications. The potential for this success to continue and accelerate has placed machine learning (ML) at the top of research, economic, and political agendas. Such unprecedented interest is fuelled by a vision of ML applicability extending to healthcare, transportation, defence, and other domains of great societal importance. Achieving this vision requires the use of ML in safety-critical applications that demand levels of assurance beyond those needed for current ML applications. Our article provides a comprehensive survey of the state of the art in the assurance of ML , i.e., in the generation of evidence that ML is sufficiently safe for its intended use. The survey covers the methods capable of providing such evidence at different stages of the machine learning lifecycle , i.e., of the complex, iterative process that starts with the collection of the data used to train an ML component for a system, and ends with the deployment of that component within the system. The article begins with a systematic presentation of the ML lifecycle and its stages. We then define assurance desiderata for each stage, review existing methods that contribute to achieving these desiderata, and identify open challenges that require further research.

ROTed: Random Oblivious Transfer for embedded devices

2021 ◽  
pp. 215-238
Author(s):  
P. Branco ◽  
L. Fiolhais ◽  
M. Goulão ◽  
P. Martins ◽  
P. Mateus ◽  
...  
Keyword(s):  
State Of The Art ◽  
Random Oracle Model ◽  
Random Oracle ◽  
Oblivious Transfer ◽  
The State ◽  
Contact Tracing ◽  
Embedded Devices ◽  
Set Intersection ◽  
Wide Range ◽  
Order Of Magnitude

Oblivious Transfer (OT) is a fundamental primitive in cryptography, supporting protocols such as Multi-Party Computation and Private Set Intersection (PSI), that are used in applications like contact discovery, remote diagnosis and contact tracing. Due to its fundamental nature, it is utterly important that its execution is secure even if arbitrarily composed with other instances of the same, or other protocols. This property can be guaranteed by proving its security under the Universal Composability model. Herein, a 3-round Random Oblivious Transfer (ROT) protocol is proposed, which achieves high computational efficiency, in the Random Oracle Model. The security of the protocol is based on the Ring Learning With Errors assumption (for which no quantum solver is known). ROT is the basis for OT extensions and, thus, achieves wide applicability, without the overhead of compiling ROTs from OTs. Finally, the protocol is implemented in a server-class Intel processor and four application-class ARM processors, all with different architectures. The usage of vector instructions provides on average a 40% speedup. The implementation shows that our proposal is at least one order of magnitude faster than the state-of-the-art, and is suitable for a wide range of applications in embedded systems, IoT, desktop, and servers. From a memory footprint perspective, there is a small increase (16%) when compared to the state-of-the-art. This increase is marginal and should not prevent the usage of the proposed protocol in a multitude of devices. In sum, the proposal achieves up to 37k ROTs/s in an Intel server-class processor and up to 5k ROTs/s in an ARM application-class processor. A PSI application, using the proposed ROT, is up to 6.6 times faster than related art.

Efficient Portfolio Construction with the Use of Multiobjective Evolutionary Algorithms: Best Practices and Performance Metrics

2015 ◽  
Vol 14 (03) ◽  
pp. 535-564 ◽  
Author(s):  
K. Liagkouras ◽  
K. Metaxiotis
Keyword(s):  
Best Practices ◽  
Evolutionary Algorithms ◽  
Portfolio Optimization ◽  
Optimization Problem ◽  
Performance Metrics ◽  
State Of The Art ◽  
The State ◽  
Multiobjective Evolutionary Algorithms ◽  
Wide Range ◽  
Portfolio Optimization Problem

This paper provides a systematic study of the technologies and algorithms associated with the implementation of multiobjective evolutionary algorithms (MOEAs) for the solution of the portfolio optimization problem. Based on the examination of the state-of-the art we provide the best practices for dealing with the complexities of the constrained portfolio optimization problem (CPOP). In particular, rigorous algorithmic and technical treatment is provided for the efficient incorporation of a wide range of real-world constraints into the MOEAs. Moreover, we address special configuration issues related to the application of MOEAs for solving the CPOP. Finally, by examining the state-of-the-art we identify the most appropriate performance metrics for the evaluation of the relevant results from the implementation of the MOEAs to the solution of the CPOP.

Reviews

1982 ◽  
Vol 13 (1) ◽  
pp. 75-78
Author(s):  
Thomas J. Cooney
Keyword(s):  
Mathematics Education ◽  
State Of The Art ◽  
Research Area ◽  
The State ◽  
National Society ◽  
Wide Range ◽  
Good Reading ◽  
Research In Mathematics Education

I found the book Selected Issues in Mathematics Education, jointly published with the National Society for the Study of Education, to be a worthy candidate for one's library. It provides interesting perspectives on a wide range of centrally important topics without getting bogged down in “disease of the week” issues that are parochial in nature. The book is not issue oriented in the sense of presenting various positions for the reader to consider and judge. Many of the chapters convey the authors' views of the state of the art in a particular research area. In some sense, the book could be a companion volume to NCTM's professional reference, Research in Mathematics Education. Still, if one is willing to look beyond what the title suggests, Selected Issues generally makes for good reading, as several authors are willing to share their insights into some rather knotty problems that are likely to be with our profession for some time.

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