1,721,113 research outputs found
Automata-theoretic techniques for reasoning and learning in linear-time temporal logics on finite traces
Full text linkThe use of temporal logics on finite traces, like Linear Temporal Logic (LTLf) and Linear Dynamic Logic (LDLf), has shown to be very powerful for AI. In particular, they have been successfully applied in several AI fields, such as temporal synthesis, FOND planning, the theory of Markov Decision Processes, Reinforcement Learning, and Business Process Management. Almost all the techniques developed in recent years rely on the well-known connection between temporal logic and automata theory. In particular, the size of a deterministic finite automaton equivalent to an LTLf/LDLf formula is, in the worst case, doubly exponentially larger than the formula. Nevertheless, such transformation is much better behaved in the infinite traces setting, which opens new avenues for algorithms that work well in practice. This thesis aims to take some of these avenues and open new ones in the theory and the applications of temporal logic in AI. As a first contribution, we present a novel compositional technique for transforming an LDLf formula into a minimal DFA and propose an efficient symbolic implementation that is competitive with state-of-the-art tools. The impressive results obtained open new possibilities for further research in this direction and provide a ready-to-use tool for several AI applications. Then, we studied new problems in applying temporal logic in the context of Reinforcement Learning and Markov Decision Processes. In particular, we study the novel problem of Restraining Bolts, in which an authority imposes a restraining specification, written in LTLf/LDLf, to the acting of a reinforcement learning agent. Despite the authority and the learning agent having different representations of the world, we can show that, under general circumstances, the agent can learn its goals to suitably conform (as much as possible) to the restraining bolt specifications. We also studied variants of this problem and methods for engineering restraining specifications to improve the learning process. In the area of LTLf synthesis, we develop the theory and the implementation of a forward technique that, in many cases, can cope with the costly translation to automata by building the automaton on the fly. We drastically improve related works on the topic by using an AND/OR graph search algorithm and Knowledge Compilation techniques to explore the search graph efficiently. The experimental results are very promising. This contribution is the starting point for cross-fertilization between the Synthesis and Planning community, particularly for developing a science of heuristics for LTLf synthesis, as has happened in Planning
An incremental learning mechanism for human activity recognition
No full textThis paper proposes an incremental mechanism for the automatic recognition of physical activities performed by humans. The specific research field has become quite relevant as it may offer important information to areas such as ambient intelligence, pervasive computing, and assistive technologies. The works in the related literature so far assume the a-priori availability of the dictionary of activities to be recognised. This work is focused on relaxing that assumption by learning and recognizing the human activities in an incremental manner based on the acquired datastreams. To this end, we designed a learning mechanism based on hidden Markov models for recognising human activities among those of a dictionary. The major novelty of the proposed mechanism is its ability to detect the occurrence of new activities and update the dictionary accordingly. We conducted experiments on a publicly available dataset of six human activities, i.e. walking, walking upstairs, walking downstairs, sitting, standing, and laying, where the efficiency of the proposed algorithm is demonstrated
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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