1,720,974 research outputs found
A Characterization of Weakly Church-Rosser Abstract Reduction Systems, not Church-Rosser
No full textBasic properties of rewriting systems can be stated in the framework of abstract reduction systems (ARS). Properties like confluence (or Church–Rosser, CR) and weak confluence (or weak Church–Rosser, WCR) and their relationships can be studied in this setting: as a matter of fact, well-known counterexamples to the implication WCR ⇒ CR have been formulated as ARS. In this paper, starting from the observation that such counterexamples are structurally similar, we set out a graph-theoretic characterization of WCR ARS that is not CR in terms of a suitable class of reduction graphs, such that in every WCR not CR ARS, we can embed at least one element of this class. Moreover, we give a tighter characterization for a restricted class of ARS enjoying a suitable regularity condition. Finally, as a consequence of our approach, we prove some interesting results about ARS using the mathematical tools developed. In particular, we prove an extension of the Newman's lemma and we find out conditions that, once assumed together with WCR property, ensure the unique normal form property. The Appendix treats two interesting examples, both generated by graph-rewriting rules, with specific combinatorial properties
Exploiting Transition Locality in the disk based Murphi Verifier
No full textExploiting Transition Locality in the disk based Murphi Verifie
A Probabilistic Approach to Space-Time Trading in Automatic Verification of Concurrent Systems
No full textA Probabilistic Approach to Space-Time Trading in Automatic Verification of Concurrent System
On the commutative equivalence of bounded context-free and regular languages: the code case
Full text linkAbstract This is the first paper of a group of three where we prove the following result. Let A be an alphabet of t letters and let ψ:A⁎⟶Nt be the corresponding Parikh morphism. Given two languages L1,L2⊆A⁎, we say that L1 is commutatively equivalent to L2 if there exists a bijection f:L1⟶L2 from L1 onto L2 such that, for every u∈L1, ψ(u)=ψ(f(u)). Then every bounded context-free language is commutatively equivalent to a regular language
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
Cost-Optimal strong planning in non-deterministic domains
No full textMany real world domains present a non-deterministic behaviour, mostly due to unpredictable environmental conditions. In this context, strong planning, i.e., finding a plan which is guaranteed to achieve the goal regardless of non-determinism, is a significant research challenge for both the planning and the control communities. In particular, the problem of cost-optimal strong planning has not been addressed so far. In this paper we provide a formal description of the cost-optimal strong planning problem in non-deterministic finite state systems, present an algorithm to solve it with good complexity bounds and formally prove the correctness and completeness of the proposed algorithm. Furthermore, we present experimental results showing the effectiveness of the proposed approach on a meaningful case study
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
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