Semi-Automated Extension of a Specialized Medical Lexicon for French

Bruno Cartoni & Pierre ZweigenbaumLIMSI-CNRS, France

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Outline

Context : UMLF for French The desired coverage The target lexical information The organisation of a specialised lexicon

Acquiring lexical information Initial coverage Obtaining lexical entries from general lexicon Guessing technique

Results Consensus guessing Acquisition of the full paradigm General improvement

Conclusion and further work

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Context : the InterSTIS project

InterSTIS: development of Terminology Server for French Medical Terminologies

Sub-Project: Improving the Lexical Coverage of a French medical lexicon (UMLF : Unified Medical Lexicon for French)

Use: support indexation process of medical texts

Issues: What is the desired lexical knowledge ? How to acquire it ?

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The desired coverage

Reference: “Term-Union” Union of 10 terminologies (CIM-10,

SNOMED, MeSH, CISMeF, …) of French medical domains, organised around concept identifiers (CUI) of the UMLS

311,518 terms 203,300 unique concepts (CUI) 94,964 word-forms

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Term-Union: example

C0000936 MSHFRE … Accommodation de l'oeiC0000936 MSHFRE … Accommodation des yeuxC0000936 MSHFRE … Accommodation oculaireC0000936 SNMIGIPFRE … accommodation visuelle...C00001558 MSHF … Voie cutanéeC00001558 MSHF … Voie intradermiqueC00001558 MSHF … Voie percutanéeC00001558 MSHF … Voie transcutanée

Observation of term variation

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Target lexical information

Term variation within Term-Union Graphemic

équilibre acido-basique – équilibre acidobasique [EN: acid-base balance]

Morphosyntactic adaptation de l'oeil - adaptation des yeux

[EN: eye adaptation]

Morphosemantic intoxication à l’alcool - intoxication alcoolique

[EN: alcohol intoxication]

Others ...

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Organisation of the specialised lexicon

3 types of relational tables for the 3 levels of representation (graphemic, inflection, derivation)

A full-entry lexicon (LMF compliant) that gathers all lexical information

…inter-maxillaire | intermaxillaireinsulino-sécrétantes | insulinosécrétantesscléro-cornéenne | sclérocornéenne …

...abdominal | abdomenaplasique | aplasiearachnoïdien | arachnoïdeargentique | argent…

…sérofibrineux | sérofibrineux | Afpmssérofibrineuse | sérofibrineux | Afpfssérofibrineux | sérofibrineux | Afpmpsérofibrineuses | sérofibrineux | Afpfp…

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Outline

Context : UMLS for French The desired coverage The target lexical information The organisation of a specialised lexicon

Acquiring lexical information Initial coverage Obtaining lexical entries from general lexicon Guessing technique

Results Consensus guessing Acquisition of the full paradigm General improvement

Conclusion and further work

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Acquiring the lexical information

Initial coverage of UMLF (previous project, UMLF, based on Baud et al. 1998) 17,192 lexical units

5,353 adjectives 11,799 nouns

36,211 word forms

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Acquiring the lexical information

From general lexicon Existing French general lexicon

(Morphalou) With a guessing technique

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Acquiring the lexical information

From guessing technique (Tanguy & Hathout 2007)

3 steps: Learning phase : calculating the most

frequent tag for each ending string in 2 existing lexicons

Guessing phase: assigning possible tag(s)

Cross validation with 2 guessing based on 2 lexicons

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Acquiring the lexical information

Acquiring the full paradigm All the inflectional forms Lemma

Based on “productive” inflectional paradigms 9 for adjectives 3 for nouns

Algorithm based on lexical tries to cluster forms of the same paradigm

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Outline

Context : UMLS for French The desired coverage The target lexical information The organisation of a specialised lexicon

Acquiring lexical information Initial coverage Obtaining lexical entries from general lexicon Guessing technique

Results Consensus guessing Acquisition of the full paradigm General improvement

Conclusion and further work

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Acquisition from general lexicon: results

74,9786,617Morphalou

81,59519,599Initial UMLF

94,964Term-Union

Remaining words to describe

Known words entries

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Acquisition with guessing techniques: results

74,978 unknown forms 44,515 analyses from Morphalou-based

program 35,438 analyses from UMLF-based

program Cross-validation: 30,137 in common

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Acquisition with guessing techniques: evaluation

Errors: 82 out of 1000 (8.2 %)

82Total

5Other

10Spelling/segmentation

1English words

5Latin words

49Proper names

12Wrong label

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Acquisition of the full paradigm: Results

4,453 paradigms captured (incomplete or not, grouping 9352 word forms) 3,308 adjectives 514 nouns

Automatic extension for the full paradigms (with canonical forms only)

Manually checked for the others

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General improvement

25,7%70,6028,088Acquisition

21,0%74,97817,828Morphalou

14,1%81,59536,211UMLF-v1

CoverageStill unknown in Term-union

Forms added

Source

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Outline

Context : UMLS for French The desired coverage The target lexical information The organisation of a specialized lexicon

Acquiring lexical information Initial coverage Obtaining lexical entries from general lexicon Guessing technique

Results Consensus guessing Acquisition of the full paradigm General improvement

Conclusion and further work

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Discussion and conclusion

The acquisition and evaluation of specialised lexical resources require a specific reference Term-Union Extract (full) lexical information Assess lexical needs and target

Other acquisition techniques (CRF for inflectional information, rule-based techniques for derivational information)

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Acknowledgment

This work was partially funded by project InterSTIS (ANR-07-TECSAN-010)

InterSTIS project: www.interstis.org