1,721,033 research outputs found
Riding the Storm in a Probabilistic Model Checking Landscape
No full textProbabilistic model checking is a formal verification technique to check whether stochastic models satisfy properties of interest. Along with a rich theory, the community has developed mature tool support, which in turn has been applied to a set of industrial case studies. This paper demonstrates various abilities of the probabilistic model checker Storm by a set of simple and more accessible examples.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
What is the Best Algorithm for MDP Model Checking? Replication Package
No full textThis artefact allows to review and replicate the experiments from the paper What is the Best Algorithm for MDP Model Checking?.
The package contains all original logfiles and the scripts that extract the relevant data from those logs to generate the plots as in the paper.
Furthermore, the artefact contains the exercised version of the model checking tool `Storm` with its dependencies and convenient installation scripts as well as all benchmark instances.
The user can thus replicate all experiments from the paper.
An appropriate subset of the experiments is given to allow a review in a timely manner. In addition, single experiments can be handpicked for replication.
This is a mild adaptation of the artefact for the paper "A Practitioner's Guide to MDP Model Checking Algorithms by Hartmanns et al. (TACAS'23)".This artefact was tested using the virtual machine (VM) for the TACAS'23 artefact evaluation, available at https://doi.org/10.5281/zenodo.7113222.
The VM is based on Ubuntu 22.04. Use the root password `tacas23`.
Other Linux and MacOS systems should work as well
Verification of multi-objective Markov models
No full textProbabilistic systems evolve based on environmental events that occur with a certain probability. For such systems to perform well, we are often interested in multiple objectives, i.e., quantitative performance measures like the probability of a failure or the expected time until task completion. Sometimes, these objectives conflict with each other: minimizing the failure probability possibly means completing the task takes longer. Compromises need to be found. We consider Markov models---particularly Markov decision processes (MDPs) and Markov Automata (MAs). These state-based modeling formalisms describe a system in its random environment. Starting from an initial state, the transitioning behavior in MDPs is determined by probabilistic and nondeterministic choices. MAs further extend MDPs by exponentially distributed continuous time delays. Rewards can be attached to states or transitions to model system quantities such as energy consumption, productivity, or monetary costs. Objectives are formally specified by a mapping from (infinite) system executions to the value of interest, e.g., the total accumulated costs or the average energy consumption. The expected value of an objective is defined once the nondeterminism is resolved using a strategy---intuitively reflecting the choices of a system controller. Different strategies induce different expected objective values. Multi-objective verification of MDPs and MAs analyzes the interplay between the considered objectives and identifies which trade-offs between expected objective values are possible, i.e., achievable by some strategy. We study practically efficient methods to compute the set of achievable solutions. For this, we establish a general framework and its instantiation for (undiscounted) total reachability reward objectives, long-run average reward objectives, and reward-bounded objectives. We propagate the errors made by approximative methods, yielding sound under- and over-approximations. We further consider multi-dimensional quantiles that ask under which reward constraints a given objective value is achievable. Finally, we investigate a setting in which the strategies must be simple, i.e., non-randomized and with limited memory access. All presented approaches are integrated into the state-of-the-art probabilistic model checker Storm. An extensive evaluation of this implementation on a broad set of multi-objective benchmarks shows that our approaches scale to large models with millions of states
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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