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## -*- mode: html; coding: utf-8; -*-
## $Id$
## This file is part of CDS Invenio.
## Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 CERN.
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## along with CDS Invenio; if not, write to the Free Software Foundation, Inc.,
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<!-- WebDoc-Page-Title: BibClassify Admin Guide -->
<!-- WebDoc-Page-Navtrail: <a class="navtrail" href="<WEBURL>/help/admin<lang:link/>">_(Admin Area)_</a> -->
<!-- WebDoc-Page-Revision: $Id$ -->
<h2>Contents</h2>
<strong>1. <a href="#1">Overview</a></strong><br />
1.1 <a href="#1.1">Thesaurus</a><br />
1.2 <a href="#1.2">Keyword extraction</a><br />
<strong>2. <a href="#2">Running BibClassify</a></strong><br />
<a name="1"></a><h2>1. Overview</h2>
<p>BibClassify automatically extracts keywords from fulltext documents.
The automatic assignment of keywords to textual documents has clear
benefits in the digital library environment as it aids
catalogization, classification and retrieval of documents.</p>
<a name="1.1"></a><h3>1.1 Thesaurus</h3>
<p> BibClassify performs an extraction of keywords based on the
recurrence of specific terms, taken from a controlled vocabulary. A
controlled vocabulary is a thesaurus of all the terms that are
relevant in a specific context. When a context is defined by a
discipline or branch of knowledge then the vocabulary is said to be a
<em>subject thesaurus</em>. Various existing subject thesauri can be found <a href="http://www.lub.lu.se/metadata/subject-help.html">here</a>.</p>
<p> A subject thesarus can be expressed in several different
formats. Different institutions/disciplines have developed different
ways of representing their vocabulary systems. BibClassify accepts thesauri in two formats:</p>
<ul>
<li> <b>Simple text</b>. <br />
This is a simple list of allowed keywords. One keyword per line. E.g. <br />
<blockquote>
<pre>
asymmetry
asymptotic behavior
ATLAS
atmosphere
</pre>
</blockquote>
</li><li> <b> RDF SKOS taxonomy </b>. <br />
This is a richer and more complex structure to describe concepts. E.g. <br />
<blockquote>
<pre>
<Concept rdf:about="http://cern.ch/thesauri/HEP.rdf#asymmetry">
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.yieldasymmetry"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.timeasymmetry"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.timereversalasymmetry"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.supernovaasymmetry"/>
<prefLabel xml:lang="en">asymmetry</prefLabel>
<hiddenLabel xml:lang="en">/asymmetr\w*/</hiddenLabel>
<hiddenLabel xml:lang="en">/nonsymmetric\w*/</hiddenLabel>
</Concept>
<Concept rdf:about="http://cern.ch/thesauri/HEP.rdf#asymptoticbehavior">
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.transformationasymptoticbehavior"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.totalcrosssectionasymptoticbehavior"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.space-timeasymptoticbehavior"/>
<prefLabel xml:lang="en">asymptotic behavior</prefLabel>
<altLabel xml:lang="en">asymptotic behaviour</altLabel>
</Concept>
<Concept rdf:about="http://cern.ch/thesauri/HEP.rdf#ATLAS">
<prefLabel xml:lang="en">ATLAS</prefLabel>
</Concept>
<Concept rdf:about="http://cern.ch/thesauri/HEP.rdf#atmosphere">
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.nucleusatmosphere"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.neutrinoatmosphere"/>
<composite rdf:resource="http://cern.ch/thesauri/HEP.rdf#Composite.muonatmosphere"/>
<prefLabel xml:lang="en">atmosphere</prefLabel>
<hiddenLabel xml:lang="en">/atmospher\w*/</hiddenLabel>
</Concept>
</pre>
</blockquote>
</li></ul>
In RDF SKOS, every keyword is wrapped around a <em>concept</em> which
encapsulates the full semantics and hierarchical status of a term -
including synonyms, alternative forms, broader concepts, notes and so
on - rather than just a plain keyword.
<p> The specification of the SKOS language and <a href="http://www.w3.org/TR/2005/WD-swbp-thesaurus-pubguide-20050517/">various manuals</a> that
aid the building of a semantic thesaurus can be found at the <a href="http://www.w3.org/TR/2005/WD-swbp-skos-core-guide-20051102/">SKOS W3C
website</a>. Furthermore, BibClassify can function on top
of an extended version of SKOS, which includes special elements such
as keychains, composite keywords and special annotations. The
extension of the SKOS language is documented in the <a href="<WEBURL>/hacking/bibclassify/">hacking guide</a>.</p>
<a name="1.2"></a><h3>1.1 Keyword extraction</h3>
<p>BibClassify computes the keywords of a fulltext document based on
the frequency of thesaurus terms in it. In other words, it calculates
how many times a thesaurus keyword (and its alternative and hidden
labels, defined in the taxonomy) appear in a text and it ranks the
results. Unlike other similar systems, BibClassify does not use any
machine learning or AI methodologies - just plain phrase matching
using <a href="http://en.wikipedia.org/wiki/Regex">regular expressions</a>: it exploits the conformation and richness
of the thesaurus to produce accurate results. It is then clear that
BibClassify performs best on top of rich, well-structured, subject
thesauri expressed in the RDF SKOS language. The simple text mode,
described in 1.1, has been retained only for historical and
demonstrative reasons.</p>
<p> A detailed account of the phrase matching mechanisms used by
BibClassify is included in the <a href="<WEBURL>/hacking/bibclassify/">hacking guide</a>.</p>
<a name="2"></a><h2>2. Running BibClassify</h2>
<p><span class="adminbox"> <b>Dependencies.</b> BibClassify
requires Python <a href="http://rdflib.net/">RDFLib</a> in
order to process the RDF SKOS taxonomy.</span></p>
<p>In order to extract relevant keywords from a document
<code>fulltext.pdf</code> based on a controlled vocabulary
<code>thesaurus.rdf</code>, you would run BibClassify as follows:</p>
<blockquote>
<pre>
$ bibclassify -t fulltext.pdf -K thesaurus.rdf
</pre>
</blockquote>
<p>Here, the following basic parameters were used:</p>
<ul>
<li><code>-f, --file=FILENAME</code>.<br />
The path to the PDF document that you would like to extract keywords from. If you
would like to analyse a text (ASCII) file, rather than a PDF, you can use the <code>-t, --textfile=FILENAME</code>
parameter instead.</li>
<li><code>-K, --taxonomy=FILENAME</code>.<br />
The path to the RDF SKOS thesaurus. Make sure that the RDF file is
well-formed and validated. If you would like to use a simple text
thesaurus (one keyword per line), you can use the paramater <code>-k,
--thesaurus=FILENAME</code> instead (NB. this mode is deprecated). </li>
</ul>
<p>In addition, you can tweak the output and performance of BibClassify by setting the following parameters:</p>
<ul>
<li><code>-o, --output=HTML|TEXT</code>.<br />
Sets the desired output to html or text (default is text). The html
output generates an html page containing a tag cloud representation of
the most recurrent keywords in the fulltext. A sample html output is shown below.</li>
<li><code>-m, --mode=PARTIAL|FULL</code>.<br />
Sets the desired processing mode, partial or full (default is full). The
partial mode will run BibClassify on the initial portion of the document
(abstract) and a small set of selected random pages. The full mode runs on the whole
of the document. Although both modes yield similar results, the partial
mode is only reccommended when performance times are an issue or when
dealing with extremely large documents (over 150 pages).</li>
<li><code>-q, --spires</code>.<br />
When set, the generated keywords (composite keywords) are output in
the traditional <a href="http://www.slac.stanford.edu/spires/">SPIRES</a> format, i.e.
<code>keyword1, keyword2</code> rather than the standard
BibClassify format <code>keyword1: keyword2</code></li>
<li><code>-n, --nkeywords=NUMBER</code>.<br />
This parameter sets the number of output (single) keywords that will be output (default is 25).</li>
<li><code>-l, --limit=NUMBER</code>.<br />
This parameter sets the maximum number of single keywords that will make part of
the pool of composite candidates, i.e. the single keywords that occur in the vicinity creating sequences of keywords.
(default is 70). Tweaking with this value can have drastic effects on
the generated results. Please check the <a href="<WEBURL>/hacking/bibclassify/">hacking guide</a> to find out more.</li>
</ul>
<p><span class="adminbox"> <b>NB.</b> BibClassify can run as a CDS Invenio
module or as a standalone program. If you already run a server with a CDS Invenio installation,
you can simply run <em>/opt/cds-invenio/bin/bibclassify</em>. Otherwise, run <em>python bibclassifylib.py</em> and you might need to set
a couple of variables manually (location of pdftotext binary and
temporary directory)</li></span></p>
<p>As an example, running BibClassify on document <a
href="http://cdsweb.cern.ch/record/977446">hep-ph/0608096</a>
using the high-energy physics SKOS taxonomy (<code>HEP.rdf</code>) would yield the following results (text output):
<pre><code>
<b>Composite keywords:</b>
22 inflaton: decay [38, 82]
20 energy: density [26, 21]
9 field theory: scalar [0, 0]
8 effect: nonperturbative [23, 42]
8 baryon: asymmetry [11, 18]
6 supersymmetry: flat direction [29, 144]
4 operator: nonrenormalizable [9, 5]
4 interaction: nonlinear [21, 4]
4 decay: time [82, 30]
3 potential: scalar [27, 16]
2 time: conformal [30, 4]
2 symmetry: U(1) [7, 5]
2 supersymmetry: potential [29, 27]
2 inflaton: oscillation [38, 22]
2 coupling: minimal [18, 6]
2 coupling: conformal [18, 4]
1 temperature: reheating [6, 10]
1 supersymmetry: minimal [29, 6]
1 resonance: effect [15, 23]
1 operator: scalar [9, 16]
1 n: decay [5, 82]
1 inflaton: potential [38, 27]
1 fundamental constant: fine structure [0, 0]
1 entropy: density [3, 21]
1 coupling: gauge [18, 18]
<b>Single keywords:</b>
80 preheating
58 mass
29 rotation
14 inflation
12 magnetic moment
11 fluctuation
9 gravitation
8 Hubble constant
7 scaling
7 mixing
7 longitudinal
5 supergravity
4 gauge boson
4 boundary condition
3 matter
3 grand unified theory
</pre></code>
or, the following keyword-cloud HTML visualization:<br />
<br />
<img src="<WEBURL>/img/admin/bibclassify-admin-guide-cloud.jpeg" alt="tag-cloud for document hep-ph/0608096" border="0" />
</p>
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