Acta Cybernetica http://cyber.bibl.u-szeged.hu/index.php/actcybern <div id="main-content" class="region clearfix"> <div class="region region-content"> <div id="block-system-main" class="block block-system"> <div class="content"> <div id="node-30" class="node node-page clearfix"> <div class="content"> <div class="field field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div class="field-item even"> <p><img style="margin-left: 10px; margin-right: 10px; float: right; width: 203px; height: 291px;" src="https://www.inf.u-szeged.hu/actacybernetica/ActaCover1802qh.png" alt=""> A scientific journal published by the <a href="http://www.inf.u-szeged.hu">Institute of Informatics</a>, <a href="http://www.u-szeged.hu/english/">University of Szeged</a>, <a href="http://www.szeged.hu/">Szeged</a>, <a href="http://www.fsz.bme.hu/hungary/homepage.html">Hungary</a>.</p> <p>Acta Cybernetica is abstracted by <a href="http://www.ams.org/bookstore-getitem/item=mrev">Mathematical Reviews</a>, <a href="http://www.reviews.com/">Computing Reviews</a>, <a href="http://www.zentralblatt-math.org/zmath/en/">Zentralblatt für Mathematik</a>&nbsp;and <a href="http://dl.acm.org/citation.cfm?id=J6&amp;picked=prox" target="_blank" rel="noopener">ACM Digital Library</a> It is also indexed by <a href="http://www.scopus.com/scopus/source/sourceInfo.url?sourceId=13024">Scopus</a>,&nbsp;<a href="http://www.informatik.uni-trier.de/%7Eley/db/journals/actaC/index.html">DBLP</a>, EBSCO and Emerging Sources Citation Index (ESCI).</p> <p><img src="https://www.inf.u-szeged.hu/actacybernetica/ESCI_button_clarivate.png" alt="">&nbsp;<a href="https://www.scimagojr.com/journalsearch.php?q=13024&amp;tip=sid&amp;clean=0"><img style="width: 200px; height: 200px;" src="https://www.scimagojr.com/journal_img.php?id=13024" alt=""></a></p> </div> </div> </div> </div> </div> </div> </div> </div> </div> University of Szeged, Institute of Informatics en-US Acta Cybernetica 0324-721X Preface http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4091 <p>The 11th Conference of PhD Students in Computer Science (CSCS) was organized by the Institute of Informatics of the University of Szeged (SZTE) and held in Szeged, Hungary, between June 25-27, 2018.</p> Attila Kertész Copyright (c) 2019-05-21 2019-05-21 24 1 1 3 10.14232/actacyb.24.1.2019.1 Towards a Classification to Facilitate the Design of Domain-Specific Visual Languages http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4001 <p>Domain-specific visual languages (DSVLs) are specialized modeling languages that allow the effective management of the behavior and the structure of software programs and systems in a specific domain. Each DSVL has its specific structural and graphical characteristics depending on the problem domain. In the recent decade, a wide range of tools and methodologies have been introduced to support the design of DSVLs for various domains, therefore it can be a challenging task to choose the most appropriate technique for the design process. Our research aims to present a classification to guide the identification of the most relevant and appropriate methodologies in the given scenario. The classification is capable enough to provide a clear and precise understanding of the main aspects that can facilitate the design of DSVLs.</p> Sándor Bácsi Gergely Mezei Copyright (c) 2019 Acta Cybernetica 2019-05-21 2019-05-21 24 1 5 16 10.14232/actacyb.24.1.2019.2 Operations on Signed Distance Functions http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4004 <p>We present a theoretical overview of signed distance functions and analyze how this representation changes when applying an offset transformation. First, we analyze the properties of signed distance and the sets they describe.</p> <p>Second, we introduce our main theorem regarding the distance to an offset set in (X,||.||) strictly normed Banach spaces. An offset set of D in X is the set of points equidistant to D. We show when such a set can be represented by f(x)-c=0, where c denotes the radius of the offset. Finally, we explain these results for applications that offset signed distance functions.</p> Csaba Bálint Gábor Valasek Lajos Gergó Copyright (c) 2019-05-21 2019-05-21 24 1 17 28 10.14232/actacyb.24.1.2019.3 Multi Party Computation Motivated by the Birthday Problem http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3992 <p>Suppose there are n people in a classroom and we want to decide if there are two of them who were born on the same day of the year. The well-known birthday paradox is concerned with the probability of this event and is discussed in many textbooks on probability. In this paper we focus on cryptographic aspects of the problem: how can we decide if there is a collision of birthdays without the participants disclosing their respective date of birth. We propose several procedures for solving this in a privacy-preserving way and compare them according to their computational and communication complexity.</p> Péter Hudoba Péter Burcsi Copyright (c) 2019-05-21 2019-05-21 24 1 29 41 10.14232/actacyb.24.1.2019.4 Benchmarking Graph Database Backends—What Works Well with Wikidata? http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3988 <p>Knowledge bases often utilize graphs as logical model. RDF-based knowledge bases (KB) are prime examples, as RDF (Resource Description Framework) does use graph as logical model. Graph databases are an emerging breed of NoSQL-type databases, offering graph as the logical model. Although there are specialized databases, the so-called triple stores, for storing RDF data, graph databases can also be promising candidates for storing knowledge. In this paper, we benchmark different graph database implementations loaded with Wikidata, a real-life, large-scale knowledge base. Graph databases come in all shapes and sizes, offer different APIs and graph models. Hence we used a measurement system, that can abstract away the API differences. For the modeling aspect, we made measurements with different graph encodings previously suggested in the literature, in order to observe the impact of the encoding aspect on the overall performance.</p> <p style="-qt-paragraph-type: empty; -qt-block-indent: 0; text-indent: 0px; margin: 0px;">&nbsp;</p> Tibor Kovács Gábor Simon Gergely Mezei Copyright (c) 2019 Acta Cybernetica 2019-05-21 2019-05-21 24 1 43 60 10.14232/actacyb.24.1.2019.5 Keeping P4 Switches Fast and Fault-free through Automatic Verification http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4000 <p>The networking dataplane is going through a paradigm shift as softwarization of switches sees an increased pull from the market. Yet, software tooling to support development with these new technologies is still in its infancy.<br>In this work, we introduce a framework for verifying performance requirement conformance of data plane protocols defined in the P4 language . We present a framework that transforms a P4 program in a versatile symbolic formula which can be utilized to answer various performance queries. We represented the system using denotational semantics and it can be easily extended with low-level target-dependent information. We demonstrate the operation of this system on a toy specification.</p> Dániel Lukács Máté Tejfel Gergely Pongrácz Copyright (c) 2019-05-21 2019-05-21 24 1 61 81 10.14232/actacyb.24.1.2019.6 Multi-Cloud Management Strategies for Simulating IoT Applications http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4015 <div style="left: 137.593px; top: 512.527px; font-size: 10.3028px; font-family: sans-serif; transform: scaleX(0.971937);">The Internet of Things (IoT) paradigm is closely coupled with cloud technologies, and the support for managing sensor data is one of the primary concerns of Cloud Computing. IoT-Cloud systems are widely used to manage sensors and different smart devices connected to the cloud, hence a large amount of data is generated by these things that need to be efficiently stored and processed. Simulation platforms have the advantage of enabling the investigation of complex systems without the need of purchasing and installing physical resources. In our previous work, we chose the DISSECT-CF simulator to model IoT-Cloud systems, and we also introduced provider policies to enable cost-aware policies resource management. The aim of this paper is to further extend the simulation capabilities of this tool by enabling multi-cloud management. In this paper we introduce four cloud selection strategies aimed to reduce application execution time and utilization costs. We detail our proposed method towards multi-cloud extension, and evaluate defined strategies through a meteorological application.</div> András Márkus József Dániel Dombi Copyright (c) 2019-05-21 2019-05-21 24 1 83 103 10.14232/actacyb.24.1.2019.7 Different Types of Search Algorithms for Rough Sets http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3999 <p><span class="fontstyle0">Based on the available information in many cases it can happen that two objects cannot be distinguished. If a set of data is given and in this set<br>two objects have the same attribute values, then these two objects are called indiscernible. This indiscernibility has an effect on the membership relation,<br>because in some cases it makes our judgment uncertain about a given object. The uncertainty appears because if something about an object is needed to be<br>stated, then all the objects that are indiscernible from the given object must be taken into consideration. The indiscernibility relation is an equivalence<br>relation which represents background knowledge embedded in an information system. In a Pawlakian system this relation is used in set approximation.<br>Correlation clustering is a clustering technique which generates a partition. In the authors’ previous research the possible usage of the correlation clustering<br>in rough set theory was investigated. In this paper the authors show how different types of search algorithms affect the set approximation.</span></p> David Nagy Tamas Mihalydeak Laszlo Aszalos Copyright (c) 2019-05-21 2019-05-21 24 1 105 120 10.14232/actacyb.24.1.2019.8 LZ based Compression Benchmark on PE Files http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3993 <p>The key element in runtime compression is the compression algorithm itself, that is used during processing. It has to be small in enough in decompression bytecode size to fit in the final executable, yet have to provide the best possible compression ratio. In our work we benchmark the top LZ based compression methods on Windows PE (both exe and dll) files, and present the results including the decompression overhead and the compression rates.</p> Zsombor Paroczi Copyright (c) 2019-05-21 2019-05-21 24 1 121 129 10.14232/actacyb.24.1.2019.9 A Preparation Guide for Java Call Graph Comparison http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3991 <p>Call graphs provide basis for numerous interprocedural analysers and tools, therefore it is crucial how precisely they are constructed. Developers need to know the features of a call graph builder before applying it to subsequent algorithms. The characteristics of call graph builders are best understood by comparing the generated call graphs themselves. The comparison can be done by matching the corresponding nodes in each graph and then analysing the found methods and calls.</p> <p>In this paper, we developed a process for pairing the nodes of multiple call graphs produced for the same source code. As the six static analysers that we collected for call graph building handles Java language elements differently, it was necessary to refine the basic name-wise pairing mechanism in several steps.&nbsp; Two language elements, the anonymous and generic methods, needed extra consideration. We describe the steps of improvement and our final solution to achieve the best possible pairing through the analysis of the Apache Commons-Math project.</p> Edit Pengő Zoltán Ságodi Copyright (c) 2019-05-21 2019-05-21 24 1 131 155 10.14232/actacyb.24.1.2019.10 Combining Common Sense Rules and Machine Learning to Understand Object Manipulation http://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/4013 <p>Automatic situation understanding in videos has improved remarkably in recent years. However, state-of-the-art methods still have considerable shortcomings: they usually require training data for each object class present and may have high false positive or false negative rates, making them impractical for general applications. We study a case that has a limited goal in a narrow context and argue about the complexity of the general problem. We suggest to solve this problem by including common sense rules and by exploiting various state-of-the art deep neural networks (DNNs) as the detectors of the conditions of those rules.</p> <p>We want to deal with the manipulation of unknown objects at a remote table. We have two action types to be detected: `picking up an object from the table' and `putting an object onto the table' and due to remote monitoring, we consider monocular observation. We quantitatively evaluate the performance of the system on manually annotated video segments, present precision and recall scores. We also discuss issues on machine reasoning. We conclude that the proposed neural-symbolic approach a) diminishes the required size of training data and b) enables new applications where labeled data are difficult or expensive to get.</p> András Sárkány Máté Csákvári Mike Olasz Copyright (c) 2019-05-21 2019-05-21 24 1 157 172 10.14232/actacyb.24.1.2019.11