1,721,028 research outputs found
Semantical and computational aspects of Horn approximations
No full textSelman and Kautz proposed a method, called Horn approximation, for speeding up inference in propositional Knowledge Bases. Their technique is based on the compilation of a propositional formula into a pair of Horn formulae: a Horn Greatest Lower Bound (GLB) and a Horn Least Upper Bound (LUB). In this paper we focus on GLBs and address two questions that have been only marginally addressed so far: (1) what is the semantics of the Horn GLBs? (2) what is the exact complexity of finding them? We obtain semantical as well as computational results. The major semantical result is: The set of minimal models of a propositional formula and the set of minimum models of its Horn GLBs are the same. The major computational result is: Finding a Horn GLB of a propositional formula in CNF is NP-equivalent, (C) 2000 Elsevier Science B.V. All rights reserved
Computing the Shapley Value in Allocation Problems: Approximations and Bounds, with an Application to the Italian VQR Research Assessment Program
No full textIn allocation problems, a given set of goods are assigned to agents in such a
way that the social welfare is maximised, that is, the largest possible global
worth is achieved. When goods are indivisible, it is possible to use money
compensation to perform a fair allocation taking into account the actual
contribution of all agents to the social welfare. Coalitional games provide a
formal mathematical framework to model such problems, in particular the Shapley
value is a solution concept widely used for assigning worths to agents in a
fair way. Unfortunately, computing this value is a -hard problem, so
that applying this good theoretical notion is often quite difficult in
real-world problems.
We describe useful properties that allow us to greatly simplify the instances
of allocation problems, without affecting the Shapley value of any player.
Moreover, we propose algorithms for computing lower bounds and upper bounds of
the Shapley value, which in some cases provide the exact result and that can be
combined with approximation algorithms.
The proposed techniques have been implemented and tested on a real-world
application of allocation problems, namely, the Italian research assessment
program, known as VQR. For the large university considered in the experiments,
the problem involves thousands of agents and goods (here, researchers and their
research products). The algorithms described in the paper are able to compute
the Shapley value for most of those agents, and to get a good approximation of
the Shapley value for all of them
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
ASP and ontologies for reasoning on business processes
No full textIn this paper we show that Answer Set Programming (ASP) can accommodate for domain ontologies in modeling and reasoning about Business Processes, especially for process verification. In this work, knowledge on the process domain is expressed in a low-complexity description logic (DL), and terms from the ontology can be used in embedding business rules in the model as well as in expressing constraints that should be verified to achieve compliance by design. Causal rules for reasoning on side-effects of activities in the process domain can be derived, based on knowledge expressed in the DL. We show how ASP can accommodate them, relying on reasoning about actions and change, for process analysis, and, in particular, for verifying formulas in temporal logic
Memory Management in Resource-Bounded Agents
No full textIn intelligent agents, memory has a very important and decisive role for the choice of future behaviors, since it is progressively formed through the agent’s interactions with the external environment. Previous work exists in the logic concerning the formalization of the reasoning on the formation of beliefs and the interaction with the background knowledge in non-omniscient agents. We extend this work by inserting the concept of time through a particular function that assigns a “timing” to beliefs and inferences
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
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