TY - CHAP A1 - Kiy, Alexander A1 - Geßner, Hendrik A1 - Lucke, Ulrike A1 - Grünewald, Franka T1 - A Hybrid and Modular Framework for Mobile Campus Applications T2 - i-com N2 - Mobile devices and associated applications (apps) are an indispensable part of daily life and provide access to important information anytime and anywhere. However, the availability of university-wide services in the mobile sector is still poor. If they exist they usually result from individual activities of students and teachers. Mobile applications can have an essential impact on the improvement of students’ self-organization as well as on the design and enhancement of specific learning scenarios, though. This article introduces a mobile campus app framework, which integrates central campus services and decentralized learning applications. An analysis of strengths and weaknesses of different approaches is presented to summarize and evaluate them in terms of requirements, development, maintenance and operation. The article discusses the underlying service-oriented architecture that allows transferring the campus app to other universities or institutions at reasonable cost. It concludes with a presentation of the results as well as ongoing discussions and future work KW - Mobile Campus Application KW - Hybrid App KW - Framework KW - Service-oriented Architecture Y1 - 2015 UR - http://www.degruyter.com/view/j/icom.2015.14.issue-1/icom-2015-0016/icom-2015-0016.xml U6 - https://doi.org/10.1515/icom-2015-0016 SN - 2196-6826 VL - 2015 IS - 14 SP - 63 EP - 73 PB - de Gruyter CY - Berlin ER - TY - JOUR A1 - Liang, Feng A1 - Liu, Yunzhen A1 - Liu, Hai A1 - Ma, Shilong A1 - Schnor, Bettina T1 - A Parallel Job Execution Time Estimation Approach Based on User Submission Patterns within Computational Grids JF - International journal of parallel programming N2 - Scheduling performance in computational grid can potentially benefit a lot from accurate execution time estimation for parallel jobs. Most existing approaches for the parallel job execution time estimation, however, require ample past job traces and the explicit correlations between the job execution time and the outer layout parameters such as the consumed processor numbers, the user-estimated execution time and the job ID, which are hard to obtain or reveal. This paper presents and evaluates a novel execution time estimation approach for parallel jobs, the user-behavior clustering for execution time estimation, which can give more accurate execution time estimation for parallel jobs through exploring the job similarity and revealing the user submission patterns. Experiment results show that compared to the state-of-art algorithms, our approach can improve the accuracy of the job execution time estimation up to 5.6 %, meanwhile the time that our approach spends on calculation can be reduced up to 3.8 %. KW - User submission pattern KW - Parallel job execution time estimation KW - Computational grid Y1 - 2015 U6 - https://doi.org/10.1007/s10766-013-0294-1 SN - 0885-7458 SN - 1573-7640 VL - 43 IS - 3 SP - 440 EP - 454 PB - Springer CY - New York ER - TY - JOUR A1 - Pablo Alarcon, Pedro A1 - Arroyo, Fernando A1 - Bordihn, Henning A1 - Mitrana, Victor A1 - Mueller, Mike T1 - Ambiguity of the multiple interpretations on regular languages JF - Fundamenta informaticae N2 - A multiple interpretation scheme is an ordered sequence of morphisms. The ordered multiple interpretation of a word is obtained by concatenating the images of that word in the given order of morphisms. The arbitrary multiple interpretation of a word is the semigroup generated by the images of that word. These interpretations are naturally extended to languages. Four types of ambiguity of multiple interpretation schemata on a language are defined: o-ambiguity, internal ambiguity, weakly external ambiguity and strongly external ambiguity. We investigate the problem of deciding whether a multiple interpretation scheme is ambiguous on regular languages. KW - Multiple interpretation scheme KW - regular language KW - o-ambiguity KW - internal ambiguity KW - external ambiguity Y1 - 2015 U6 - https://doi.org/10.3233/FI-2015-1200 SN - 0169-2968 SN - 1875-8681 VL - 138 IS - 1-2 SP - 85 EP - 95 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Lindauer, Marius A1 - Hoos, Holger H. A1 - Hutter, Frank A1 - Schaub, Torsten H. T1 - An automatically configured algorithm selector JF - The journal of artificial intelligence research N2 - Algorithm selection (AS) techniques - which involve choosing from a set of algorithms the one expected to solve a given problem instance most efficiently - have substantially improved the state of the art in solving many prominent AI problems, such as SAT, CSP, ASP, MAXSAT and QBF. Although several AS procedures have been introduced, not too surprisingly, none of them dominates all others across all AS scenarios. Furthermore, these procedures have parameters whose optimal values vary across AS scenarios. This holds specifically for the machine learning techniques that form the core of current AS procedures, and for their hyperparameters. Therefore, to successfully apply AS to new problems, algorithms and benchmark sets, two questions need to be answered: (i) how to select an AS approach and (ii) how to set its parameters effectively. We address both of these problems simultaneously by using automated algorithm configuration. Specifically, we demonstrate that we can automatically configure claspfolio 2, which implements a large variety of different AS approaches and their respective parameters in a single, highly-parameterized algorithm framework. Our approach, dubbed AutoFolio, allows researchers and practitioners across a broad range of applications to exploit the combined power of many different AS methods. We demonstrate AutoFolio can significantly improve the performance of claspfolio 2 on 8 out of the 13 scenarios from the Algorithm Selection Library, leads to new state-of-the-art algorithm selectors for 7 of these scenarios, and matches state-of-the-art performance (statistically) on all other scenarios. Compared to the best single algorithm for each AS scenario, AutoFolio achieves average speedup factors between 1.3 and 15.4. Y1 - 2015 SN - 1076-9757 SN - 1943-5037 VL - 53 SP - 745 EP - 778 PB - AI Access Foundation CY - Marina del Rey ER - TY - JOUR A1 - Hoos, Holger A1 - Kaminski, Roland A1 - Lindauer, Marius A1 - Schaub, Torsten H. T1 - aspeed: Solver scheduling via answer set programming JF - Theory and practice of logic programming N2 - Although Boolean Constraint Technology has made tremendous progress over the last decade, the efficacy of state-of-the-art solvers is known to vary considerably across different types of problem instances, and is known to depend strongly on algorithm parameters. This problem was addressed by means of a simple, yet effective approach using handmade, uniform, and unordered schedules of multiple solvers in ppfolio, which showed very impressive performance in the 2011 Satisfiability Testing (SAT) Competition. Inspired by this, we take advantage of the modeling and solving capacities of Answer Set Programming (ASP) to automatically determine more refined, that is, nonuniform and ordered solver schedules from the existing benchmarking data. We begin by formulating the determination of such schedules as multi-criteria optimization problems and provide corresponding ASP encodings. The resulting encodings are easily customizable for different settings, and the computation of optimum schedules can mostly be done in the blink of an eye, even when dealing with large runtime data sets stemming from many solvers on hundreds to thousands of instances. Also, the fact that our approach can be customized easily enabled us to swiftly adapt it to generate parallel schedules for multi-processor machines. KW - algorithm schedules KW - answer set programming KW - portfolio-based solving Y1 - 2015 U6 - https://doi.org/10.1017/S1471068414000015 SN - 1471-0684 SN - 1475-3081 VL - 15 SP - 117 EP - 142 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Ohrndorf, Laura T1 - Assignments in Computer Science Education BT - Results of an Analysis of Textbooks, Curricula and other Resources JF - KEYCIT 2014 - Key Competencies in Informatics and ICT N2 - In this paper we describe the recent state of our research project concerning computer science teachers’ knowledge on students’ cognition. We did a comprehensive analysis of textbooks, curricula and other resources, which give teachers guidance to formulate assignments. In comparison to other subjects there are only a few concepts and strategies taught to prospective computer science teachers in university. We summarize them and given an overview on our empirical approach to measure this knowledge. KW - Pedagogical content knowledge KW - computer science teachers KW - students’ knowledge KW - students’ conceptions Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82868 SN - 1868-0844 SN - 2191-1940 IS - 7 SP - 327 EP - 333 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Fichte, Johannes Klaus A1 - Szeider, Stefan T1 - Backdoors to tractable answer set programming JF - Artificial intelligence N2 - Answer Set Programming (ASP) is an increasingly popular framework for declarative programming that admits the description of problems by means of rules and constraints that form a disjunctive logic program. In particular, many Al problems such as reasoning in a nonmonotonic setting can be directly formulated in ASP. Although the main problems of ASP are of high computational complexity, complete for the second level of the Polynomial Hierarchy, several restrictions of ASP have been identified in the literature, under which ASP problems become tractable. In this paper we use the concept of backdoors to identify new restrictions that make ASP problems tractable. Small backdoors are sets of atoms that represent "clever reasoning shortcuts" through the search space and represent a hidden structure in the problem input. The concept of backdoors is widely used in theoretical investigations in the areas of propositional satisfiability and constraint satisfaction. We show that it can be fruitfully adapted to ASP. We demonstrate how backdoors can serve as a unifying framework that accommodates several tractable restrictions of ASP known from the literature. Furthermore, we show how backdoors allow us to deploy recent algorithmic results from parameterized complexity theory to the domain of answer set programming. (C) 2015 Elsevier B.V. All rights reserved. KW - Answer set programming KW - Backdoors KW - Computational complexity KW - Parameterized complexity KW - Kernelization Y1 - 2015 U6 - https://doi.org/10.1016/j.artint.2014.12.001 SN - 0004-3702 SN - 1872-7921 VL - 220 SP - 64 EP - 103 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Opel, Simone A1 - Kramer, Matthias A1 - Trommen, Michael A1 - Pottbäcker, Florian A1 - Ilaghef, Youssef T1 - BugHunt BT - A Motivating Approach to Self-Directed Problem-solving in Operating Systems JF - KEYCIT 2014 - Key Competencies in Informatics and ICT N2 - Competencies related to operating systems and computer security are usually taught systematically. In this paper we present a different approach, in which students have to remove virus-like behaviour on their respective computers, which has been induced by software developed for this purpose. They have to develop appropriate problem-solving strategies and thereby explore essential elements of the operating system. The approach was implemented exemplarily in two computer science courses at a regional general upper secondary school and showed great motivation and interest in the participating students. KW - Educational software KW - operating system KW - student activation KW - problem-solving KW - interactive course KW - interactive workshop KW - edutainment KW - secondary computer science education Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82693 SN - 1868-0844 SN - 2191-1940 IS - 7 SP - 217 EP - 233 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Bröker, Kathrin A1 - Kastens, Uwe A1 - Magenheim, Johannes T1 - Competences of Undergraduate Computer Science Students JF - KEYCIT 2014 - Key Competencies in Informatics and ICT N2 - The paper presents two approaches to the development of a Computer Science Competence Model for the needs of curriculum development and evaluation in Higher Education. A normativetheoretical approach is based on the AKT and ACM/IEEE curriculum and will be used within the recommendations of the German Informatics Society (GI) for the design of CS curricula. An empirically oriented approach refines the categories of the first one with regard to specific subject areas by conducting content analysis on CS curricula of important universities from several countries. The refined model will be used for the needs of students’ e-assessment and subsequent affirmative action of the CS departments. KW - Competences KW - Competence Measurement KW - Curriculum Development KW - Computer Science Education KW - Recommendations for CS-Curricula in Higher Education Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82613 SN - 1868-0844 SN - 2191-1940 IS - 7 SP - 77 EP - 96 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Bottino, Rosa A1 - Chioccariello, Augusto T1 - Computational Thinking BT - Videogames, Educational Robotics, and other Powerful Ideas to Think with JF - KEYCIT 2014 - Key Competencies in Informatics and ICT N2 - Digital technology has radically changed the way people work in industry, finance, services, media and commerce. Informatics has contributed to the scientific and technological development of our society in general and to the digital revolution in particular. Computational thinking is the term indicating the key ideas of this discipline that might be included in the key competencies underlying the curriculum of compulsory education. The educational potential of informatics has a history dating back to the sixties. In this article, we briefly revisit this history looking for lessons learned. In particular, we focus on experiences of teaching and learning programming. However, computational thinking is more than coding. It is a way of thinking and practicing interactive dynamic modeling with computers. We advocate that learners can practice computational thinking in playful contexts where they can develop personal projects, for example building videogames and/or robots, share and discuss their construction with others. In our view, this approach allows an integration of computational thinking in the K-12 curriculum across disciplines. KW - Computational thinking KW - programming in context KW - informatics education Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82820 SN - 1868-0844 SN - 2191-1940 IS - 7 SP - 301 EP - 309 PB - Universitätsverlag Potsdam CY - Potsdam ER -