6,495 research outputs found
From ternary relationship to relational tables: a case against common beliefs
The transformation from n-ary relationships to a relational database
schema has never been really fully analyzed. This paper presents one of
the several ternary cases ignored by the ER-to-RM literature. The case
shows that the following common belief is wrong: Given a set of FDs over
a table resulting in a non-3NF situation, it is always possible to
obtain a fully equivalent set of 3NF tables, without adding other
restrictions than candidate keys and inclusion dependencies.Postprint (published version
Graphene: Semantically-Linked Propositions in Open Information Extraction
We present an Open Information Extraction (IE) approach that uses a
two-layered transformation stage consisting of a clausal disembedding layer and
a phrasal disembedding layer, together with rhetorical relation identification.
In that way, we convert sentences that present a complex linguistic structure
into simplified, syntactically sound sentences, from which we can extract
propositions that are represented in a two-layered hierarchy in the form of
core relational tuples and accompanying contextual information which are
semantically linked via rhetorical relations. In a comparative evaluation, we
demonstrate that our reference implementation Graphene outperforms
state-of-the-art Open IE systems in the construction of correct n-ary
predicate-argument structures. Moreover, we show that existing Open IE
approaches can benefit from the transformation process of our framework.Comment: 27th International Conference on Computational Linguistics (COLING
2018
Transforming N-ary relationships to database schemas: an old and forgotten problem
The N-ary relationships, have been traditionally a source of
confusion and still are. One important source of confusion is that the
term cardinality in a relationship has several interpretations, two of
them being very popular. But none of the two approaches, nor the two
together, allow us to express all the possible cardinality patterns. The
transformations from all the possible relationships to database schemas
have never been described by the existing literature. Using the 14
ternary patterns as example, we discuss these transformations
particularly the transformations from the patterns ignored in the
literature.Postprint (published version
Revealing structure-function relationships in functional flow networks via persistent homology
Complex networks encountered in biology are often characterized by
significant structural diversity. Whether it be differences in the
three-dimensional structure of allosteric proteins, or the variation among the
micro-scale structures of organisms' cerebral vasculature systems, identifying
relationships between structure and function often poses a difficult challenge.
Here we showcase an approach to characterizing structure-function relationships
in complex networks applied in the context of flow networks tuned to perform
specific functions. Using persistent homology, we analyze flow networks tuned
to perform complex multifunctional tasks, answering the question of how local
changes in the network structure coordinate to create functionality at at the
scale of the entire network. We find that the response of such networks encodes
hidden topological features - sectors of uniform pressure - that are not
apparent in the underlying network architectures, Regardless of differences in
local connectivity, these features provide a universal topological description
for all networks that perform these types of functions. We show that these
features correlate strongly with the tuned response, providing a clear
topological relationship between structure and function and structural insight
into the limits of multifunctionality.Comment: 22 pages (double column), 12 figure
Finding Temporally Consistent Occlusion Boundaries in Videos using Geometric Context
We present an algorithm for finding temporally consistent occlusion
boundaries in videos to support segmentation of dynamic scenes. We learn
occlusion boundaries in a pairwise Markov random field (MRF) framework. We
first estimate the probability of an spatio-temporal edge being an occlusion
boundary by using appearance, flow, and geometric features. Next, we enforce
occlusion boundary continuity in a MRF model by learning pairwise occlusion
probabilities using a random forest. Then, we temporally smooth boundaries to
remove temporal inconsistencies in occlusion boundary estimation. Our proposed
framework provides an efficient approach for finding temporally consistent
occlusion boundaries in video by utilizing causality, redundancy in videos, and
semantic layout of the scene. We have developed a dataset with fully annotated
ground-truth occlusion boundaries of over 30 videos ($5000 frames). This
dataset is used to evaluate temporal occlusion boundaries and provides a much
needed baseline for future studies. We perform experiments to demonstrate the
role of scene layout, and temporal information for occlusion reasoning in
dynamic scenes.Comment: Applications of Computer Vision (WACV), 2015 IEEE Winter Conference
o
A yield curve perspective on uncovered interest parity
This article uses a dynamic multi-factor model of the yield curve with a rational-expectations, general-equilibrium-economy foundation to investigate the uncovered interest parity hypothesis(UIPH). The yield curve model is used to decompose the interest rate data used in the UIPH regressions into components that reflect rationally-based expectations of the cyclical and fundamental components of the underlying economy. The UIPH is not rejected based on the fundamental components of interest rates, but is soundly rejected based on the cyclical components. These results provide empirical support for suggestions in the existing theoretical literature that rationally-based interest rate and exchange rate dynamics associated with cyclical inter-linkages between the economy and financial markets may contribute materially to the UIPH puzzle
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