scholarly journals Algorithm Selection for Combinatorial Search Problems: A Survey

AI Magazine ◽  
2014 ◽  
Vol 35 (3) ◽  
pp. 48-60 ◽  
Author(s):  
Lars Kotthoff
Keyword(s):  
Problem Instance ◽  
Combinatorial Search ◽  
Search Problems ◽  
Algorithm Selection ◽  
Performance Improvements ◽  
Selection Systems ◽  
Significant Performance ◽  
Comprehensive Classification ◽  
Made In

The algorithm selection problem is concerned with selecting the best algorithm to solve a given problem instance on a case-by-case basis. It has become especially relevant in the last decade, with researchers increasingly investigating how to identify the most suitable existing algorithm for solving a problem instance instead of developing new algorithms. This survey presents an overview of this work focusing on the contributions made in the area of combinatorial search problems, where algorithm selection techniques have achieved significant performance improvements. We unify and organise the vast literature according to criteria that determine algorithm selection systems in practice. The comprehensive classification of approaches identifies and analyses the different directions from which algorithm selection has been approached. This article contrasts and compares different methods for solving the problem as well as ways of using these solutions.

COMPARISON AND EVALUATION OF A CLASS OF IDA* ALGORITHMS

1994 ◽  
Vol 03 (04) ◽  
pp. 493-523 ◽  
Author(s):  
BENJAMIN W. WAH ◽  
YI SHANG
Keyword(s):  
Lower Bounds ◽  
Problem Instance ◽  
Combinatorial Search ◽  
Search Problems ◽  
Minimization Problems

In this paper, we study the performance of various IDA*-style searches and investigate methods to improve their performance by predicting in each stage the threshold to be used for pruning. Without loss of generality, we consider minimization problems in this paper. We first present three models to approximate the distribution of the number of search nodes by lower bounds: exponential, geometric, and linear, and illustrate these distributions based on some well-known combinatorial search problems. Based on these distributions, we show the performance of an ideal IDA* algorithm and identify reasons why existing IDA*-style algorithms perform well. In practice, we will be able to know from experience the type of distribution for a given problem instance, but will not be able to know the parameters of this distribution until the instance is solved. Hence, we develop RIDA*, a method that estimates dynamically the parameters of the distribution, and predicts the best threshold to be used in each stage. Finally, we compare the performance of several IDA*-style algorithms—Korf’s IDA* and RBFS, RIDA*, IDA*_CR and DFS*—on several application problems, and identify conditions under which each of these algorithms will perform well.

Eine semantische Klassifizierung von Weil-Sätzen

2021 ◽  
Vol 66 (1) ◽  
pp. 297-324
Author(s):  
Sibilla Cantarini ◽  
Chiara de Bastiani
Keyword(s):  
Three Dimensional ◽  
Semantic Relations ◽  
Dimensional Model ◽  
Verb Second ◽  
Three Dimensional Model ◽  
Semantic Classification ◽  
Conceptual Relations ◽  
Comprehensive Classification ◽  
Made In

"A Semantic Classification of Weil-clauses. In the present study, we will elaborate a classification of clauses introduced by weil ‘because’; this classification combines different views on the concepts of cause and motive and their respective linguistic realization. In this paper, the three-dimensional model proposed by Sweetser (1990) will be combined with the distinction between cause and motive made in Prandi/De Santis (2011) and Prandi (2013), with the purpose of formulating a taxonomy of linguistic causality. Corpus research aimed at testing the afore-mentioned classification shows that the subordinating conjunction weil, which is usually defined as the prototypical causal subordinator in traditional grammars, introduces different conceptual relations, which would be difficult to identify without a comprehensive classification of the semantic relations introduced by this subordinator. Finally, further applications of the proposed classification involving the opposition between clauses headed by weil with verb-end and verb-second syntax will be proposed. It will be argued that the verb-second syntax serves a particular function in the encoding of semantic relations. Keywords: cause, motive, traditional grammars, semantic relations, verb-end, verb-second "

ASPECTS IN BUILDING A COMPANY WEB-SITE AND ITS ROLE FOR THE DEVELOPMENT OF BUSINESS

2018 ◽  
pp. 117-124
Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva
Keyword(s):  
Life Cycle ◽  
Web Site ◽  
The Internet ◽  
A Company ◽  
The Web ◽  
Design Construction ◽  
Made In ◽  
Site Types

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.

Vegetation on technogenic habitats in the far-north taiga and south forest-tundra of the European North-East of Russia. Alliance Chamerio angustifolii–Matricarion hookeri A. Ishbirdin et al. 1996

2019 ◽  
pp. 77-94
Author(s):  
I. A. Likhanova ◽  
G. S. Shushpannikova ◽  
L. P. Turubanova
Keyword(s):  
Komi Republic ◽  
Oil Fields ◽  
Soil Enrichment ◽  
Far North ◽  
North East ◽  
European North ◽  
Ecological Scales ◽  
Floristic Classification ◽  
Made In

The results of floristic classification of technogenic vegetation (alliance Chamerio angustifolii–Matricarion hookeri A. Ishbirdin et al. 1996, order Chamerio–Betuletalia nanae Khusainov et al. in Sumina 2012, class Matricario–Poetea arcticae A. Ishbirdin in Sumina 2012) conducted by the Braun-Blanquet method (Braun-Blanquet, 1964; Mirkin, Naumova, 1998) are given. 98 geobotanical relevés, made in 1981–2013 on areas of oil fields and suburbs of the Usinsk city (Komi Republic) (56–60о N, 67–66о E), were involved into analysis (Fig. 1). The ecological parameters like moisture (F) and mineral nitrogen soil enrichment (N) were assessed using the Ellenberg ecological scales (Ellenberg, 1974).

scholarly journals An Attention-Based Multilayer GRU Model for Multistep-Ahead Short-Term Load Forecasting

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1639
Author(s):  
Seungmin Jung ◽  
Jihoon Moon ◽  
Sungwoo Park ◽  
Eenjun Hwang
Keyword(s):  
Power Consumption ◽  
Prediction Models ◽  
Short Term Memory ◽  
Load Forecasting ◽  
Input Sequence ◽  
Short Term ◽  
Performance Improvements ◽  
Short Term Load Forecasting ◽  
Significant Performance ◽  
Input Variables

Recently, multistep-ahead prediction has attracted much attention in electric load forecasting because it can deal with sudden changes in power consumption caused by various events such as fire and heat wave for a day from the present time. On the other hand, recurrent neural networks (RNNs), including long short-term memory and gated recurrent unit (GRU) networks, can reflect the previous point well to predict the current point. Due to this property, they have been widely used for multistep-ahead prediction. The GRU model is simple and easy to implement; however, its prediction performance is limited because it considers all input variables equally. In this paper, we propose a short-term load forecasting model using an attention based GRU to focus more on the crucial variables and demonstrate that this can achieve significant performance improvements, especially when the input sequence of RNN is long. Through extensive experiments, we show that the proposed model outperforms other recent multistep-ahead prediction models in the building-level power consumption forecasting.

scholarly journals UV Spectral Classification of B Stars

1985 ◽  
Vol 111 ◽  
pp. 411-413
Author(s):  
Janet Rountree ◽  
George Sonneborn ◽  
Robert J. Panek
Keyword(s):  
Classification System ◽  
Classification Criteria ◽  
High Dispersion ◽  
Spectral Classification ◽  
Early Type ◽  
B Stars ◽  
Dimensional Classification ◽  
Early Type Stars ◽  
Comprehensive Classification

Previous studies of ultraviolet spectral classification have been insufficient to establish a comprehensive classification system for ultraviolet spectra of early-type stars because of inadequate spectral resolution. We have initiated a new study of ultraviolet spectral classification of B stars using high-dispersion IUE archival data. High-dispersion SWP spectra of MK standards and other B stars are retrieved from the IUE archives and numerically degraded to a uniform resolution of 0.25 or 0.50 Å. The spectra (in the form of plots or photowrites) are then visually examined with the aim of setting up a two-dimensional classification matrix. We follow the method used to create the MK classification system for visual spectra. The purpose of this work is to examine the applicability of the MK system (and in particular, the set of standard stars) in the ultraviolet, and to establish classification criteria in this spectral region.

scholarly journals Data Downlink System in the Vast IOT Node Condition Assisted by UAV, Large Intelligent Surface, and Power and Data Beacon

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5748
Author(s):  
Zhibo Zhang ◽  
Qing Chang ◽  
Na Zhao ◽  
Chen Li ◽  
Tianrun Li
Keyword(s):  
Communication Systems ◽  
Optimization Problems ◽  
Minimum Energy ◽  
Numerical Algorithms ◽  
Flight Trajectory ◽  
Performance Improvements ◽  
Minimum Energy Consumption ◽  
Significant Performance ◽  
Downlink System ◽  
The Internet Of Things

The future development of communication systems will create a great demand for the internet of things (IOT), where the overall control of all IOT nodes will become an important problem. Considering the essential issues of miniaturization and energy conservation, in this study, a new data downlink system is designed in which all IOT nodes harvest energy first and then receive data. To avoid the unsolvable problem of pre-locating all positions of vast IOT nodes, a device called the power and data beacon (PDB) is proposed. This acts as a relay station for energy and data. In addition, we model future scenes in which a communication system is assisted by unmanned aerial vehicles (UAVs), large intelligent surfaces (LISs), and PDBs. In this paper, we propose and solve the problem of determining the optimal flight trajectory to reach the minimum energy consumption or minimum time consumption. Four future feasible scenes are analyzed and then the optimization problems are solved based on numerical algorithms. Simulation results show that there are significant performance improvements in energy/time with the deployment of LISs and reasonable UAV trajectory planning.

VESTA 3for three-dimensional visualization of crystal, volumetric and morphology data

2011 ◽  
Vol 44 (6) ◽  
pp. 1272-1276 ◽  
Author(s):  
Koichi Momma ◽  
Fujio Izumi
Keyword(s):  
Search Algorithm ◽  
Voronoi Tessellation ◽  
Three Dimensional ◽  
Structure Parameters ◽  
Volumetric Data ◽  
Complex Molecules ◽  
Visualization System ◽  
Performance Improvements ◽  
Significant Performance

VESTAis a three-dimensional visualization system for crystallographic studies and electronic state calculations. It has been upgraded to the latest version,VESTA 3, implementing new features including drawing the external morphology of crystals; superimposing multiple structural models, volumetric data and crystal faces; calculation of electron and nuclear densities from structure parameters; calculation of Patterson functions from structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels; determination of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures; undo and redo in graphical user interface operations; and significant performance improvements in rendering isosurfaces and calculating slices.

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