1,721,012 research outputs found
Querying the deep web: Back to the foundations
No full textThe Deep Web is the large corpus of data accessible on the Web through forms and presented in dynamically-generated pages, but not indexable as static pages, and therefore invisible to search engines. Deep Web data are usually modelled as relations with so-called access limitations, that is, they can be queried only by selecting certain at-Tributes. In this paper we give some fundamental complexity results on the problem of processing conjunctive (select-project-join) queries on re- lational data with access limitations.SCOPUS: cp.pinfo:eu-repo/semantics/publishe
Regular resolution for CNFs with almost bounded one-sided treewidth
Get PDFWe introduce a one-sided incidence tree decomposition of a CNF .
This is a tree decomposition of the incidence graph of where the
underlying tree is rooted and the set of bags containing each clause induces a
directed path in the tree. The one-sided treewidth is the smallest width of a
one-sided incidence tree decomposition.
We consider a class of unsatisfiable CNF that can be turned into
one of one sided treewidth at most by removal of at most clauses. We
show that the size of regular resolution for this class of CNFs is FPT
parameterized by and . The results contributes to understanding the
complexity of resolution for CNFs of bounded incidence treewidth, an open
problem well known in the areas of proof complexity and knowledge compilation.
In particular, the result significantly generalizes all the restricted classes
of CNFs of bounded incidence treewidth that are known to admit an FPT sized
resolution.
The proof includes an auxiliary result and several new notions that may be of
an independent interest
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
Classification of OBDD Size for Monotone 2-CNFs
Get PDFWe introduce a new graph parameter called linear upper maximum induced matching width lu-mim width, denoted for a graph G by lu(G). We prove that the smallest size of the obdd for φ, the monotone 2-cnf corresponding to G, is sandwiched between 2^{lu(G)} and n^{O(lu(G))}. The upper bound is based on a combinatorial statement that might be of an independent interest. We show that the bounds in terms of this parameter are best possible.
The new parameter is closely related to two existing parameters: linear maximum induced matching width (lmim width) and linear special induced matching width (lsim width). We prove that lu-mim width lies strictly in between these two parameters, being dominated by lsim width and dominating lmim width. We conclude that neither of the two existing parameters can be used instead of lu-mim width to characterize the size of obdds for monotone 2-cnfs and this justifies introduction of the new parameter
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
A 2O(k)poly(n) algorithm for the parameterized convex recoloring problem
No full textIn this paper we present a parameterized algorithm that solves the Convex Recoloring problem for trees in . This improves the currently best upper bound of achieved by Moran and Snir
On the read-once property of branching programs and CNFs of bounded treewidth
No full textfor non-deterministic (syntactic) read-once branching programs (nrobps) on functions expressible as cnfs with treewidth at most k of their primal graphs. This lower bound rules out the possibility of fixed-parameter space complexity of nrobps parameterized by k. We use lower bound for nrobps to obtain a quasi-polynomial separation between Free Binary Decision Diagrams and Decision Decomposable Negation Normal Forms, essentially matching the existing upper bound introduced by Beame et al. (Proceedings of the twenty-ninth conference on uncertainty in artificial intelligence, Bellevue, 2013) and thus proving the tightness of the latter
A faster solving of the maximum independent set problem for graphs with maximal degree 3
No full textWe present an O(1:1034,) for the problem obtained by Chen et al [2]
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