143,756 research outputs found
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
Customizing digital library interfaces with Greenstone
Digital libraries are organized, focused collections of information. They are focused on a particular topic or themeâand good digital libraries will articulate the principles governing what is included. They are organized to make information accessible in particular, well-defined, waysâand good ones will include a description of how the information is organized (Lesk, 1997).
The Greenstone digital library software is intended to help users construct simple collections of information very quickly. Indeed, only a few minutes of the user's time are needed to set up a collection based on a standard design and initiate the building process. Collections may be largeâsome comprise Gbytes of text; millions of documents. Furthermore, even larger volumes of information may be associated with a collectionâtypically audio, image, and video, with textual metadata. Once initiated, the mechanical process of building the collection may take from a few moments for a tiny collection to several hours for a multi-Gbyte oneâperhaps even a day if it involves many different full-text indexes
The High-Temperature Expansion of the Hierarchical Ising Model: From Poincar\'e Symmetry to an Algebraic Algorithm
We show that the hierarchical model at finite volume has a symmetry group
which can be decomposed into rotations and translations as the familiar
Poincar\'e groups. Using these symmetries, we show that the intricate sums
appearing in the calculation of the high-temperature expansion of the magnetic
susceptibility can be performed, at least up to the fourth order, using
elementary algebraic manipulations which can be implemented with a computer.
These symmetries appear more clearly if we use the 2-adic fractions to label
the sites. We then apply the new algebraic methods to the calculation of
quantities having a random walk interpretation. In particular, we show that the
probability of returning at the starting point after steps has poles at
, where is a free parameter playing a role similar to the
dimensionality in nearest neighbor models.Comment: 24 Pages, includes 2 short Mathematica programs appended after "/end"
uses phyzzx.te
Universality, Scaling and Triviality in a Hierarchical Field Theory
Using polynomial truncations of the Fourier transform of the RG
transformation of Dyson's hierarchical model, we show that it is possible to
calculate very accurately the renormalized quantities in the symmetric phase.
Numerical results regarding the corrections to the scaling laws, (i.e finite
cut-off dependence) triviality, hyperscaling, universality and high-accuracy
determinations of the critical exponents are discussed.Comment: LATTICE98(spin
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