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The Value of Usage Scenarios for Thesaurus Alignment in Cultural Heritage Context. Antoine Isaac , Claus Zinn, Henk Matthezing, Lourens van der Meij, Stefan Schlobach, Shenghui Wang Cultural Heritage on the Semantic Web Workshop Oct. 12 th , 2007. Introduction. One important problem in CH

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the value of usage scenarios for thesaurus alignment in cultural heritage context

The Value of Usage Scenarios for Thesaurus Alignment in Cultural Heritage Context

Antoine Isaac, Claus Zinn, Henk Matthezing, Lourens van der Meij, Stefan Schlobach, Shenghui Wang

Cultural Heritage on the Semantic Web Workshop

Oct. 12th, 2007

introduction
OAEI 2007: Results from the Library TrackIntroduction
  • One important problem in CH
  • Heterogeneity of description resources
    • Thesauri (at large)
    • Classification schemes, subject heading lists …
  • Hampers access across collections
introduction1
OAEI 2007: Results from the Library TrackIntroduction

Ontology alignment can help

  • Semantic links between ontology elements
    • o1:Cat owl:equivalentClass o2:Chat
  • Using automatic tools
    • E.g. exploiting labels, structure
introduction2
OAEI 2007: Results from the Library TrackIntroduction
  • Problem: not much on alignment applications
  • Need further research on context-specific alignment
    • Generation
    • Deployment
    • Evaluation
  • Important context dimension: application scenarios
agenda
OAEI 2007: Results from the Library TrackAgenda
  • Introduction
  • Dutch National Library Scenarios for Alignment
  • Book Re-indexing
  • Scenario-specific Evaluation
kb and thesaurus alignement
OAEI 2007: Results from the Library TrackKB and Thesaurus Alignement
  • National Library of the Netherlands (KB)
  • 2 main collections
  • Each described (indexed) by its own thesaurus
  • Problem: maintenance optimized wrt. redundancy/size?
usage scenarios for thesaurus alignment at kb
OAEI 2007: Results from the Library TrackUsage Scenarios for Thesaurus Alignment at KB
  • Concept-based search
    • Retrieving GTT-indexed books using Brinkman concepts
  • Re-indexing
    • Indexing GTT-indexed books with Brinkman concepts
  • Integration of one Thesaurus into the other
    • Inserting GTT elements into the Brinkman thesaurus
  • Thesaurus Merging
    • Building a new thesaurus fro GTT and Brinkman
  • Free-text search
    • matching user search terms to both GTT or Brinkman concepts
  • Navigation:
    • browse the 2 collections through a merged version of the thesauri
agenda1
OAEI 2007: Results from the Library TrackAgenda
  • Introduction
  • Dutch National Library Scenarios for Alignment
  • Book Re-indexing
  • Scenario-specific Evaluation
the book re indexing scenario
OAEI 2007: Results from the Library TrackThe Book Re-indexing Scenario
  • Scenario: re-indexing of GTT-indexed books by Brinkman concepts
the book re indexing scenario1
OAEI 2007: Results from the Library TrackThe Book Re-indexing Scenario
  • If one of the thesauri is dropped, legacy data has to be indexed according to the other voc.
    • Automatically
    • Semi-automatically, users presented with candidate annotations
scenario requirements
OAEI 2007: Results from the Library TrackScenario Requirements
  • Mapping sets of GTT concepts to sets of Brinkman
    • alignreindex: {g1,…,gm} →{b1,…,bn}
    • Option where users select based on probabilities
      • Candidates concepts are given weights (e.g. [0;1])
      • alignreindex’: {g1,…,gm} →{(b1,w1),…,(bn,wn)}
  • Generated index should be generally small
    • 99.2% of depot books indexed with no more than 3 Brinkman concepts
semantic interpretation of re indexing function
OAEI 2007: Results from the Library TrackSemantic Interpretation of Re-indexing Function

1-1 case: g1->b1

  • b1 is semantically equivalent to g1
    • OK
  • b1 is more general than g1
    • Loss of information
    • Possible if b1 is the most specific subsumer of g1’s meanings
    • Indexing specificity rule
semantic interpretation of re indexing function1
OAEI 2007: Results from the Library TrackSemantic Interpretation of Re-indexing Function

Generic cases: combinations of concepts

  • Considerations on semantic links are the same
  • Combination matters

Indexing is post-coordinated

    • {“Geography”; “the Netherlands”} in GTT

-> book about geography of the Netherlands

  • Different granularities/indexing points of view
    • Brinkman has “Netherlands; Geography”
problem of alignment deployment
OAEI 2007: Results from the Library TrackProblem of Alignment Deployment

Results of existing tools may need re-interpretation

  • Unclear semantics of mapping links
    • "=","<"
    • weights
  • Single concepts involved in mappings
example of alignment deployment approach
OAEI 2007: Results from the Library TrackExample of Alignment Deployment Approach
  • Starting from similarity measures over both thesauri
    • sim(X,Y)=n
  • Aggregation strategy: simple Ranking
    • For a concept, take the top k similar concepts
    • Gather GTT concepts and Brinkman ones
  • Re-indexing function specified by conditions for firing rules
    • E.g., if the book indexing contains the left part of the rule
agenda2
OAEI 2007: Results from the Library TrackAgenda
  • Introduction
  • Dutch National Library Scenarios for Alignment
  • Book Re-indexing
  • Scenario-specific Evaluation
evaluation design
OAEI 2007: Results from the Library TrackEvaluation Design
  • We do not assess the rules
  • We assess their application on book indexing
  • 2 classical aspects:
    • Correctness (cf. precision)
    • Completeness (cf. recall)
evaluation design different variants and settings
OAEI 2007: Results from the Library TrackEvaluation Design: Different Variants and Settings
  • Fully automatic evaluation
    • Using the set of dually indexed books as gold standard
  • Manual evaluation 1
    • Human expert assesses candidate indices
    • Unsupervised setting: margin of error should be very low
    • Supervised setting: less strict, but size also matter
  • Manual evaluation 2
    • Same as 1, but a first index has been produced by the expert
    • Distance between the two indices is assessed
    • Eventually changing original index
human evaluation vs automatic evaluation
OAEI 2007: Results from the Library TrackHuman Evaluation vs. Automatic Evaluation

Taking into account

  • Indexing variability
    • Automatic evaluation compares with a specific indexing choice
    • Especially important if thesaurus doesn’t match book subject
  • Evaluation variability
    • Only one expert judgment is considered per book
  • Evaluation set bias
    • Dually-indexed books (may) present specific characteristics
new developments outside of paper
OAEI 2007: Results from the Library TrackNew Developments, Outside of Paper!
  • Reviews: you should add actual results of good general alignment systems as compared to your scenario
  • Ontology Alignment Evaluation Initiative
    • http://oaei.ontologymatching.org/2007
    • State-of-the-art aligners applied to specific cases
  • This paper: grounding for an OAEI Library track
    • KB vocabularies
    • Evaluation in re-indexing scenario
automatic evaluation
OAEI 2007: Results from the Library TrackAutomatic Evaluation
  • There is a gold standard for re-indexing scenario
  • General method: for dually indexed books, compare existing Brinkman annotations and new ones
automatic evaluation1
OAEI 2007: Results from the Library TrackAutomatic Evaluation
  • Book level: Precision & Recall for matched books
    • Books for which there is one good annotation
    • Minimal hint about users’ (dis)satisfaction
  • Annotation level: P & R for candidate annotations
    • Note: counting over annotations and books, not rules and concepts
    • Rules & concepts used more often are more important
automatic evaluation results
Notice: for exactMatch only

OAEI 2007: Results from the Library Track

Automatic Evaluation Results
manual evaluation method
OAEI 2007: Results from the Library TrackManual Evaluation Method

Variant 1, for supervised setting

  • Selection of 100 books
  • 4 KB evaluators
  • Paper forms + copy of books
annotation transl manual evaluation results
OAEI 2007: Results from the Library TrackAnnotation Transl.: Manual Evaluation Results

Research question: quality of candidate annotations

  • Measures used: cf. automatic evaluation
  • Performances are consistently higher

[Left: manual evaluation, Right: automatic evaluation]

annotation transl manual evaluation results1
OAEI 2007: Results from the Library TrackAnnotation Transl.: Manual Evaluation Results

Research question: evaluation variability

  • Krippendorff’s agreement coefficient (alpha)
  • High variability: overall alpha=0.62
    • <0.67, classic threshold for Computational Linguistics tasks
    • But indexing seems to be more variable than usual CL tasks
annotation transl manual evaluation results2
OAEI 2007: Results from the Library TrackAnnotation Transl.: Manual Evaluation Results

Research question: indexing variability

  • Measuring acceptability of original book indices
  • Kripendorff’s agreement for indices chosen by evaluators
    • 0.59 overall alpha confirms high variability
conclusions
OAEI 2007: Results from the Library TrackConclusions
  • Better characterization of alignment scenarios is needed
  • For a single case there are many scenarios and variants
  • Requires to elicit requirements
  • And evaluation criteria
discussion differences between scenarios
OAEI 2007: Results from the Library TrackDiscussion: Differences between scenarios?
  • Concept-based search
  • Re-indexing
  • Integration of one thesaurus into the other
  • Thesaurus merging
  • Free-text search aided by thesauri
  • Navigation
discussion differences between scenarios1
OAEI 2007: Results from the Library TrackDiscussion: Differences between scenarios?

Semantics of alignment

  • A core of primitives that are be useful
    • broader/narrower, related
  • Some constructs are more specific
    • “AND” combination for re-indexing
  • Interpretation of equivalence?
    • Thesaurus merging: “excavation” = “excavation”
    • Query reformulation: “excavation” = “archeology; Netherlands”
discussion differences between scenarios2
OAEI 2007: Results from the Library TrackDiscussion: Differences between scenarios?

Multi-concept alignment

  • Useful for re-indexing or concept-based search
  • Less for thesaurus re-engineering scenarios
    • Combinations are not fully dealt with by thesaurus formats
    • But simple links involving a same concept can be useful
      • C1 BT C2
      • C1 BT C3
discussion differences between scenarios3
OAEI 2007: Results from the Library TrackDiscussion: Differences between scenarios?

Precision and recall

  • Browsing -> emphasis on recall
  • For other scenarios, it depends on the setting

Supervised vs. unsupervised

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