1,721,188 research outputs found
Preface
Get PDFThis is a preface of the special issue of the 14th international workshop on Automated Verification of Critical Systems. This workshop covers all aspects of automated verification, including model checking, theorem proving, SAT/SMT constraint solving, abstract interpretation, and refinement pertaining to various types of critical systems which need to meet stringent dependability requirements (safety-critical, business-critical, performance-critical, etc.)
The IMITATOR benchmarks library 2.1: A benchmarks library for extended parametric timed automata
No full text<p>We present here the IMITATOR benchmarks library 2.1: A benchmarks library for extended parametric timed automata</p>
<p> </p>
<p>We present two archives:</p>
<p>- one (benchmarks.zip) with the models and the properties</p>
<p>- one (full.zip) with the benchmarks and all the results: the expected results, generated PDF and graphics, and a whole standalone Web page (more or less equivalent to <a href="https://www.imitator.fr/static/library.html">www.imitator.fr/static/library.html</a>) summarizing all benchmarks</p>
<p> </p>
<p>See a full description in the TAP 2021 paper ("<a href="https://link.springer.com/10.1007/978-3-030-79379-1_3">A Benchmarks Library for Extended Parametric Timed Automata</a>")</p>
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Using SMT for dealing with nondeterminism in ASM-based runtime verification
No full textIn runtime verification, operational models describing the expected system behavior offer some advantages with respect to declarative specifications of properties, especially when designers are more accustomed to them. However, nondeterminism in the specification usually affects performances of those operational methods that explicitly represent all the possible conformant states. In this paper, we tackle the problem of dealing with nondeterminism in an operational runtime verification approach based on the use of Abstract State Machines (ASMs). We propose an SMT-based technique in which ASM computations are symbolically represented and conformance verification is performed by means of satisfability checking. Experiments show that, in most of the cases, the symbolic approach performs better than a technique for ASM-based runtime verification explicitly representing the conformant states
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Strong Connectivity and Shortest Paths for Checking Models
Get PDFWe study directed graphs and focus on algorithms for two classical graph problems; the decomposition of a graph into Strongly Connected Components (SCCs), and the Single-Source Shortest Path problem. In particular, we concentrate on the development of new graph search algorithms for checking models, i.e. techniques that allow a user to analyse a system and verify whether particular properties are maintained. Our contributions advance the performance of state-of-the-art techniques for model checking and conformance checking. Moreover, we additionally pursue new directions to broaden the horizons of both fields. We developed a multi-core algorithm for on-the-fly SCC decomposition that scales effectively on many-core systems. In its construction, we additionally developed an iterable concurrent union-find structure that may be used in other applications. We considered SCCs in the domain of model checking and showed that our SCC decomposition algorithm can be applied to outperform the state-of-the-art techniques. Additionally, we explored how more general automata could be model checked by providing techniques to achieve this. We studied the shortest path problem in the context of conformance checking, in particular for the computation of alignments. By exploiting characteristic choices for the cost function, we compute alignments via an algorithm based on symbolic reachability. We also consider an alternative cost function and show how this leads to a new data structure and algorithm. Finally, we studied new problems for Parametric Timed Automata (PTAs), which extend timed automata with unknown constant values, or parameters. We developed algorithms to synthesize parameter values for the best- and worst-case behaviour. For instance, computing all parameter valuations such that a target location is reached in minimal- or maximal time
Testing Reactive Systems with Data : Enumerative Methods and Constraint Solving
Get PDFSoftware faults are a well-known phenomenon. In most cases, they are just annoying – if the computer game does not work as expected – or expensive – if once again a space project fails due to some faulty data conversion. In critical systems, however, faults can have life-threatening consequences. It is the task of software quality assurance to avoid such faults, but this is a cumbersome, expensive and also erroneous undertaking. For this reason, research has been done over the last years in order to automate this task as much as possible. In this thesis, the connection of constraint solving techniques with formal methods is investigated. We have the goal to ��?nd faults in the models and implementations of reactive systems with data, such as automatic teller machines (ATMs). In order to do so, we ��?rst develop a translation of formal speci��?cations in the process algebra µCRL to a constraint logic program (CLP). In the course of this translation, we pay special attention on the fact that the CLP together with the constraint solver correctly simulates the underlying term rewriting system. One way to validate a system is the test whether this system conforms its speci��?cation. In this thesis, we develop a test process to automatically generate and execute test cases for the conformance test of data-oriented systems. The applicability of this process to process-oriented software systems is demonstrated in a case study with an ATM as the system under test. The applicability of the process to document-centered applications is shown by means of the open source web browser Mozilla Firefox. The test process is partially based on the tool TGV, which is an enumerative test case generator. It generates test cases from a system speci��?cation and a test purpose. An enumerative approach to the analysis of system speci��?cations always tries to enumerate all possible combinations of values for the system’s data elements, i.e. the system’s states. The states of those systems, which we regard here, are influenced by data of possibly in��?nite domains. Hence, the state space of such systems grows beyond all limits, it explodes, and cannot be handled anymore by enumerative algorithms. For this reason, the state space is limited prior to test case generation by a data abstraction. We use a chaotic abstraction here with all possible input data from a system’s environment being replaced by a single constant. In parallel, we generate a CLP from the system speci��?cation. With this CLP, we reintroduce the actual data at the time of test execution. This approach does not only limit the state space of the system, but also leads to a separation of system behavior and data. This allows to reuse test cases by only varying their data parameters. In the developed process, tests are executed by the tool BAiT. This tool has also been created in the course of this thesis. Some systems do not always show an identical behavior under the same circumstances. This phenomenon is known as nondeterminism. There are many reasons for nondeterminism. In most cases, input froma system’s environment is asynchronously processed by several components of the system, which do not always terminate in the same order. BAiT works as follows: The tool chooses a trace through the system behavior from the set of traces in the generated test cases. Then, it parameterizes this trace with data and tries to execute it. When the nondeterministic system digresses from the selected trace, BAiT tries to appropriately adapt it. If this can be done according to the system speci��?cation, the test can be executed further and a possibly false positive test verdict has been successfully avoided. The test of an implementation signi��?cantly reduces the numbers of faults in a system. However, the system is only tested against its speci��?cation. In many cases, this speci��?cation already does not completely ful��?ll a customer ’s expectations. In order to reduce the risk for faults further, the models of the system themselves also have to be veri��?ed. This happens during model checking prior to testing the software. Again, the explosion of the state space of the system must be avoided by a suitable abstraction of the models. A consequence of model abstractions in the context of model checking are so-called false negatives. Those traces are counterexamples which point out a fault in the abstracted model, but who do not exist in the concrete one. Usually, these false negatives are ignored. In this thesis, we also develop a methodology to reuse the knowledge of potential faults by abstracting the counterexamples further and deriving a violation pattern from it. Afterwards, we search for a concrete counterexample utilizing a constraint solver
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