82,742 research outputs found
Generating Question-Answer Hierarchies
The process of knowledge acquisition can be viewed as a question-answer game
between a student and a teacher in which the student typically starts by asking
broad, open-ended questions before drilling down into specifics (Hintikka,
1981; Hakkarainen and Sintonen, 2002). This pedagogical perspective motivates a
new way of representing documents. In this paper, we present SQUASH
(Specificity-controlled Question-Answer Hierarchies), a novel and challenging
text generation task that converts an input document into a hierarchy of
question-answer pairs. Users can click on high-level questions (e.g., "Why did
Frodo leave the Fellowship?") to reveal related but more specific questions
(e.g., "Who did Frodo leave with?"). Using a question taxonomy loosely based on
Lehnert (1978), we classify questions in existing reading comprehension
datasets as either "general" or "specific". We then use these labels as input
to a pipelined system centered around a conditional neural language model. We
extensively evaluate the quality of the generated QA hierarchies through
crowdsourced experiments and report strong empirical results.Comment: ACL camera ready + technical note on pipeline modifications for demo
(15 pages
Concept-based Interactive Query Expansion Support Tool (CIQUEST)
This report describes a three-year project (2000-03) undertaken in the Information Studies
Department at The University of Sheffield and funded by Resource, The Council for
Museums, Archives and Libraries. The overall aim of the research was to provide user
support for query formulation and reformulation in searching large-scale textual resources
including those of the World Wide Web. More specifically the objectives were: to investigate
and evaluate methods for the automatic generation and organisation of concepts derived from
retrieved document sets, based on statistical methods for term weighting; and to conduct
user-based evaluations on the understanding, presentation and retrieval effectiveness of
concept structures in selecting candidate terms for interactive query expansion.
The TREC test collection formed the basis for the seven evaluative experiments conducted in
the course of the project. These formed four distinct phases in the project plan. In the first
phase, a series of experiments was conducted to investigate further techniques for concept
derivation and hierarchical organisation and structure. The second phase was concerned with
user-based validation of the concept structures. Results of phases 1 and 2 informed on the
design of the test system and the user interface was developed in phase 3. The final phase
entailed a user-based summative evaluation of the CiQuest system.
The main findings demonstrate that concept hierarchies can effectively be generated from
sets of retrieved documents and displayed to searchers in a meaningful way. The approach
provides the searcher with an overview of the contents of the retrieved documents, which in
turn facilitates the viewing of documents and selection of the most relevant ones. Concept
hierarchies are a good source of terms for query expansion and can improve precision. The
extraction of descriptive phrases as an alternative source of terms was also effective. With
respect to presentation, cascading menus were easy to browse for selecting terms and for
viewing documents. In conclusion the project dissemination programme and future work are
outlined
Generalized NLS Hierarchies from Rational Algebras
Finite rational \cw algebras are very natural structures appearing in coset
constructions when a Kac-Moody subalgebra is factored out. In this letter we
address the problem of relating these algebras to integrable hierarchies of
equations, by showing how to associate to a rational \cw algebra its
corresponding hierarchy. We work out two examples: the coset,
leading to the Non-Linear Schr\"{o}dinger hierarchy, and the coset of
the Polyakov-Bershadsky \cw algebra, leading to a -field representation of
the KP hierarchy already encountered in the literature. In such examples a
rational algebra appears as algebra of constraints when reducing a KP hierarchy
to a finite field representation. This fact arises the natural question whether
rational algebras are always associated to such reductions and whether a
classification of rational algebras can lead to a classification of the
integrable hierarchies.Comment: 12 pages, latex, preprint ENSLAPP-L-448/9
New Supersymmetrizations of the Generalized KdV Hierarchies
Recently we investigated a new supersymmetrization procedure for the KdV
hierarchy inspired in some recent work on supersymmetric matrix models. We
extend this procedure here for the generalized KdV hierarchies. The resulting
supersymmetric hierarchies are generically nonlocal, except for the case of
Boussinesque which we treat in detail. The resulting supersymmetric hierarchy
is integrable and bihamiltonian and contains the Boussinesque hierarchy as a
subhierarchy. In a particular realization, we extend it by defining
supersymmetric odd flows. We end with some comments on a slight modification of
this supersymmetrization which yields local equations for any generalized KdV
hierarchy.Comment: 10 pages, uuencoded compressed tar'd .dvi file, Bonn-HE-93-1
Disassembling the Clockwork Mechanism
The clockwork mechanism is a means of naturally generating exponential
hierarchies in theories without significant hierarchies among fundamental
parameters. We emphasize the role of interactions in the clockwork mechanism,
demonstrating that clockwork is an intrinsically abelian phenomenon precluded
in non-abelian theories such as Yang-Mills, non-linear sigma models, and
gravity. We also show that clockwork is not realized in extra-dimensional
theories through purely geometric effects, but may be generated by appropriate
localization of zero modes.Comment: 30 pages plus appendices, 4 figures. v2: Clarifications, minor
changes, and comment on 1705.10162 added. Conclusions unchange
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