219 research outputs found
The most general manner to injectively align true and predicted segments
Kirilov et al (2019) develop a metric, called Panoptic Quality (PQ), to
evaluate image segmentation methods. The metric is based on a confusion table,
and compares a predicted to a ground truth segmentation. The only non
straightforward part in this comparison is to align the segments in the two
segmentations. A metric only works well if that alignment is a partial
bijection. Kirilov et al (2019) list 3 desirable properties for a definition of
alignment: it should be simple, interpretable and effectively computable. There
are many definitions guaranteeing a partial bijection and these 3 properties.
We present the weakest: one that is both sufficient and necessary to guarantee
that the alignment is a partial bijection. This new condition is effectively
computable and natural. It simply says that the number of correctly predicted
elements (in image segmentation, the pixels) should be larger than the number
of missed, and larger than the number of spurious elements. This is strictly
weaker than the proposal in Kirilov et al (2019). In formulas, instead of |TP|>
|FN\textbar| + |FP|, the weaker condition requires that |TP|> |FN| and |TP| >
|FP|. We evaluate the new alignment condition theoretically and empirically
A Hybrid Approach to Domain-Specific Entity Linking
The current state-of-the-art Entity Linking (EL) systems are geared towards
corpora that are as heterogeneous as the Web, and therefore perform
sub-optimally on domain-specific corpora. A key open problem is how to
construct effective EL systems for specific domains, as knowledge of the local
context should in principle increase, rather than decrease, effectiveness. In
this paper we propose the hybrid use of simple specialist linkers in
combination with an existing generalist system to address this problem. Our
main findings are the following. First, we construct a new reusable benchmark
for EL on a corpus of domain-specific conversations. Second, we test the
performance of a range of approaches under the same conditions, and show that
specialist linkers obtain high precision in isolation, and high recall when
combined with generalist linkers. Hence, we can effectively exploit local
context and get the best of both worlds.Comment: SEM'1
Generalized Group Profiling for Content Customization
There is an ongoing debate on personalization, adapting results to the unique
user exploiting a user's personal history, versus customization, adapting
results to a group profile sharing one or more characteristics with the user at
hand. Personal profiles are often sparse, due to cold start problems and the
fact that users typically search for new items or information, necessitating to
back-off to customization, but group profiles often suffer from accidental
features brought in by the unique individual contributing to the group. In this
paper we propose a generalized group profiling approach that teases apart the
exact contribution of the individual user level and the "abstract" group level
by extracting a latent model that captures all, and only, the essential
features of the whole group. Our main findings are the followings. First, we
propose an efficient way of group profiling which implicitly eliminates the
general and specific features from users' models in a group and takes out the
abstract model representing the whole group. Second, we employ the resulting
models in the task of contextual suggestion. We analyse different grouping
criteria and we find that group-based suggestions improve the customization.
Third, we see that the granularity of groups affects the quality of group
profiling. We observe that grouping approach should compromise between the
level of customization and groups' size.Comment: Short paper (4 pages) published in proceedings of ACM SIGIR
Conference on Human Information Interaction and Retrieval (CHIIR'16
Modal logic of planar polygons
We study the modal logic of the closure algebra , generated by the set
of all polygons in the Euclidean plane . We show that this logic
is finitely axiomatizable, is complete with respect to the class of frames we
call "crown" frames, is not first order definable, does not have the Craig
interpolation property, and its validity problem is PSPACE-complete
An Inflationary Fixed Point Operator in XQuery
We introduce a controlled form of recursion in XQuery, inflationary fixed
points, familiar in the context of relational databases. This imposes
restrictions on the expressible types of recursion, but we show that
inflationary fixed points nevertheless are sufficiently versatile to capture a
wide range of interesting use cases, including the semantics of Regular XPath
and its core transitive closure construct.
While the optimization of general user-defined recursive functions in XQuery
appears elusive, we will describe how inflationary fixed points can be
efficiently evaluated, provided that the recursive XQuery expressions exhibit a
distributivity property. We show how distributivity can be assessed both,
syntactically and algebraically, and provide experimental evidence that XQuery
processors can substantially benefit during inflationary fixed point
evaluation.Comment: 11 pages, 10 figures, 2 table
Good Applications for Crummy Entity Linkers? The Case of Corpus Selection in Digital Humanities
Over the last decade we have made great progress in entity linking (EL)
systems, but performance may vary depending on the context and, arguably, there
are even principled limitations preventing a "perfect" EL system. This also
suggests that there may be applications for which current "imperfect" EL is
already very useful, and makes finding the "right" application as important as
building the "right" EL system. We investigate the Digital Humanities use case,
where scholars spend a considerable amount of time selecting relevant source
texts. We developed WideNet; a semantically-enhanced search tool which
leverages the strengths of (imperfect) EL without getting in the way of its
expert users. We evaluate this tool in two historical case-studies aiming to
collect a set of references to historical periods in parliamentary debates from
the last two decades; the first targeted the Dutch Golden Age, and the second
World War II. The case-studies conclude with a critical reflection on the
utility of WideNet for this kind of research, after which we outline how such a
real-world application can help to improve EL technology in general.Comment: Accepted for presentation at SEMANTiCS '1
Undecidable relativizations of algebras of relations.
In this paper we show that relativized versions of relation set algebras and cylindric set algebras have undecidable equational theories if we include coordinatewise versions of the counting operations into the similarity type. We apply these results to the guarded fragment of first-order logic
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Microfoundations
The paper argues that the microfoundations programme can be understood as an implementation of an underlying methodological principle, methodological individualism, and that it therefore shares a fundamental ambiguity with that principle, viz, whether the macro must be derived from and therefore reducible to, or rather consistent with micro-level behaviours. The pluralist conclusion of the paper is not that research guided by the principle of microfoundations is necessarily wrong, but that the exclusion of approaches not guided by that principle is indeed necessarily wrong. The argument is made via an examination of the advantages claimed for dynamic stochastic general equilibrium models, the relationship between parts and wholes in social science, and the concepts of reduction, substrate neutrality, the intentional stance, and hypostatisation
Recommended from our members
Microfoundations
This paper argues that the microfoundations programme can be understood as an implementation of an underlying methodological principle—methodological individualism—and that it therefore shares a fundamental ambiguity with that principle, viz, whether the macro must be derived from and therefore reducible to, or rather consistent with, micro-level behaviours. The pluralist conclusion of the paper is not that research guided by the principle of microfoundations is necessarily wrong, but that the exclusion of approaches not guided by that principle is indeed necessarily wrong. The argument is made via an examination of the advantages claimed for dynamic stochastic general equilibrium models, the relationship between parts and wholes in social science, and the concepts of reduction, substrate neutrality, the intentional stance, and hypostatisation
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