Finding High-frequent Synonyms of a Domain-specific Verb in English Sub-language of MEDLINE Abstracts Using WordNet

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Finding High-frequent Synonyms of a
Domain-specific Verb in English Sub-language of
MEDLINE Abstracts Using WordNet

• Chun Xiao and Dietmar Rösner
• Institut für Wissens-
• und Sprachverarbeitung (IWS),
• Faculty of Computer Science,University of
  Magdeburg,39016 Magdeburg, Germany

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Introduction MEDLINE Abstract

• MEDLINE
• Domain clinical medicine, biomedicine,
  biological and physical sciences
• Source articles from over 4,600 journals
  published throughout the world
• Coverage abstracts are included for about 52 of
  the articles.
• PubMed, an application of UMLS (unified medical
  language system), provides links within MEDLINE
  to the full text of 15 clinical medical journals
  .
• Available at http//www.ncbi.nlm.nih.gov/PubMed/

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Available Resources in the Experiment

• The test corpus consists of 800 MEDLINE abstracts
  extracted from the GENIA Corpus V3.0p and V3.01.
• Available at http//www-tsujii.is.s.u-tokyo.ac.jp
  /GENIA/
• WordNet 1.7.1

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Extraction of a Specific Relation

• Inhibitory relation
• Example Secreted from activated T cells and
  macrophages, bone marrow-derived MIP-1
  alpha/GOS19 inhibits primitive hematopoietic stem
  cells and appears to be involved in the
  homeostatic control of stem cell proliferation.
• Semantic annotations in the GENIA corpus
• protein_molecule
• cell_type

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High-frequent Verbs in the Test Corpus
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Synonym Sets (Synsets) of Verb inhibit

• Synset in WordNet
• Sense 1
• suppress, stamp down, inhibit, subdue, conquer,
  curb
• gt control, hold in, hold, contain, check,
  curb, moderate
• Sense 2
• inhibit
• gt restrict, restrain, trammel, limit,
  bound, confine, throttle
• Synset in test corpus of MEDLINE abstracts
• Inhibit, block, prevent, etc.

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Problem

• Occurrences of verbs in the two synsets in the
  test corpus of MEDLINE abstracts
• WN-synonyms suppress (69), limit (16), restrict
  (5)
• non WN-synonyms block (124), reduce (119),
  prevent(53)
• How can WordNet synsets and information from the
  corpus be combined to create domain-specific verb
  synsets?

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Three Definitions

• Language unit a text segment (a sentence,
  several sentences, or a paragraph, etc.) that
  expresses one semantic topic.
• Core word the verb, whose synset in the test
  corpus is to be found out. E.g., in this test
  inhibit is the core word.
• Keyword the word, whose corresponding verb base
  form is the core word. E.g., in this test
  inhibitor, inhibiting, and so on are keywords.

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Example

• We performed an analysis of the
  mechanisms by which two PKC inhibitors,
  Calphostin C and Staurosporine, prevent the
  FN-induced IL-1beta response. Both inhibitors
  blocked the secretion of IL-1beta protein into
  the media of peripheral blood mononuclear cells
  exposed to FN.
• Language unit two sentences
• Core word inhibit
• Keyword inhibitor (2 times)
• Local context searching window size gt3
• Verbs around the first keyword perform,
  prevent, block, expose
• Verbs around the second keyword prevent,
  perform, block, expose
• In the following test, the language unit is
  selected to be the whole abstract.

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Idea Description

• Assumption
• The synonyms of a verb co-occur much more
  frequently together with the keywords of the verb
  than together with other words in the language
  unit.
• Method
• Thus the verb chunks around the keywords are
  collected, from which the synonyms of the core
  word will be selected and filtered, using WordNet
  synset information.

• One resource
  WordNet synset information

• The other resource
  Local context information in
  the test corpus

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Distribution of Keywords of inhibit in the Test
Corpus
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Verbs around the Keywords in the Test Corpus
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Method Description I

• Expansion of WordNet Synsets (Si)
• S1 the verb collection of synonyms of all
  synonyms of the core word
• S2 the verb collection of synonyms of all verbs
  in S1
• Expansion of Stoplist (STOPk)
• STOP0 manually select 15 stop-verbs from the
  high-frequent verbs in the test corpus (e.g.,
  suggest, indicate, including the high-frequent
  antonyms of the core word)
• STOP1 the verb collection of synonyms of all
  verbs in STOP0

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Method Description II

• Verb list from the corpus (Vj)
• Verbs around the keywords in a local context
  of searching window size of j are collected.
• Synonym candidate list (Sg)
• If a verb is in Vj and also in Si, but not in
  STOPk, then add it to Sg.

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Evaluation

• Golden standard list (SG)
• A manually created synonym list, which is
  extracted from the test corpus.
• Consist of 10 verbs with the most frequent
  occurrences, in which 3 verbs come directly from
  the WordNet synset of inhibit, the rest 7 verbs
  come from its hypernym set or the expanded list
  of its synonyms.
• Recall Precision

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Result

• 60 recall of SG ltgt 93.05 occurrences in the
  test corpus

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Conclusions and Future Work

• Conclusions
• English sublanguage of MEDLINE abstract
• The core word and its keywords were
  high-frequent
• Multiword verb structures were not considered
  yet
• Balance between recall and precision expansion
  of Si and STOPk should be limited.
• Future works
• Consideration of other WordNet information
  besides synsets
• Automatic creation of stoplists
• Extraction of multiword verb structures
• Utilization of syntactic information.

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Thanks!
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Looking forward to your questions!
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Possible Errors

• Errors of POS tags between
• Adjectives ltgt Past participles
• Errors of manual works when selecting stop-verbs

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Question or Hope

• Can WordNet provide the possibility for
  accessing multiword expressions?