Alasdair J G Gray Norman Gray Iadh Ounis What is a Vocabulary 1 5 November 2008 ADASS Vocabularies in the VO What is a Controlled Vocabulary A set of terms with Label Synonyms Definition ID: 399290
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Slide1
Vocabularies in the VO
Alasdair J G Gray
Norman Gray
Iadh
OunisSlide2
What is a Vocabulary?
1
5 November 2008
ADASS - Vocabularies in the VOSlide3
What is a Controlled Vocabulary?
A set of terms with:
Label
Synonyms
Definition
Relationships to other terms:Broader termNarrower termRelated term
Example:Spiral galaxySpiral nebulaA galaxy having a spiral structureRelationships:BT: GalaxyNT: Barred spiral galaxy
RT: Spiral arm2
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ADASS - Vocabularies in the VOSlide4
Why do we need vocabularies?
Limit and define terminology
Improve search
Retrieve papers from ADS using keywords
All papers about “Binary eclipsing stars”
Process all VOEvents about “supernovae”Should also process “1a supernovae”Locating relevant resources in the registry/VizieR
Removes ambiguityImproves precision5 November 2008
ADASS - Vocabularies in the VO3Slide5
Analysis of
Registry Keywords
Problems:
Plural/singular
Case
Abbreviations
Different tags
Thanks to
Sébastien
Derriere for this data.
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ADASS - Vocabularies in the VO
75 Star
52 Galaxy
37 Stars
36 Galaxies
16 AGN
12 Cluster of Galaxies
12 Nebulae
11 Planets
10 GRB
10 Globular Clusters
8 Star Cluster
7 Nebula
6 Variable stars
5 Hot stars
5 Pulsar
4 supernova
3 Clusters of Galaxies
3
Infrared:stars
3 Quasars: general
3 Supernova
3 White dwarfs
3 galaxies
2 Comets
2 Cool stars
2 Extragalactic Source
2 Extragalactic objects
2 Infrared: stars
2 Interstellar medium
2 QSO
2
QSOs
2 SNR
2 Variable Star
2 White Dwarf
2 clusters of galaxies
2 stars
1 Asteroids
1 BL Lac
1 Be/X-ray binary stars
1 Binary stars
...Slide6
Common Vocabulary Format
Requirements:
Provide term identifiers
Unambiguous tagging
Capture semantic relationships
Poly-hierarchy structureMachine processableAllows inter-operability“Machine intelligence”
Avoids problems of:SpellingCasePlurality problemsTags
Automated reasoning:Interested in all “Supernova”Items tagged as “1a Supernova” also returned
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SKOS
W3C standard for sharing vocabularies
Based on RDF
Semantic model for describing resources
Provides URI for each term
Captures properties of termsEncodes relationships between termsEnables automated reasoningStandard serialisations
“Looser” semantics than OWLAdopted by IVOA Vocabularies standard6
5 November 2008ADASS - Vocabularies in the VOSlide8
Example SKOS Vocabulary Term
Example
“Spiral galaxy”
“Spiral nebula”
“A galaxy having a spiral structure”
Relationships: BT: “Galaxy” NT: “Barred spiral galaxy” RT: “Spiral arm”
#spiralGalaxy a concept; prefLabel “Spiral galaxy”@en;
altLabel “Spiral nebula”@en; definition “A galaxy having a spiral
structure”@en; broader #galaxy;
narrower #
barredSpiralGalaxy
;
related #
spiralArm
.
In turtle notation
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Terminology Aside
Folksonomies
Keyword tags, freely chosen – e.g.
VizieR
subjectsVocabulary
Controlled list of words with definitionsTaxonomyRelationships: Broader/Narrower/RelatedThesaurusSynonyms, antonyms, see alsoOntology
Formal specification of a shared conceptualisation – OWL“Vocabulary” used in IVOA to cover vocabularies, taxonomies, and thesauri.
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Existing Astronomical Vocabularies
Journal Keywords
Developed for tagging papers
311 terms
Actively used
Astronomy Visualization Metadata (AVM)Tagging images217 termsActively usedIAU ThesaurusDeveloped for libraries in 1993
2,551 termsNever really usedUnified Content Descriptor (UCD)Tagging resource data473 termsActively used
Published as SKOS vocabularies by the IVOA5 November 2008
ADASS - Vocabularies in the VO
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Inter-operable Vocabularies
Which vocabulary should I use?
Closest match to your needs
Relate vocabulary terms using mappings
Part of the SKOS standard
One mapping file per pair of vocabulariesChains of mappingsA
B CA C
Inter-vocabulary mappingsBroad match: more general term
Narrow match: more specific term
Related match:
associated term
Exact match:
equivalent term
Close match:
similar but not equivalent term
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Mapping EditorSlide13
Putting it all together
Use vocabulary concepts for
Tagging (using URI)
Resources in the registry
VOEvent
packetsSearching by vocabulary conceptUser keyword search converted to vocabulary URIProvides semantic advantagesReasoning about termsRelationshipsMappings
Requires mechanism to convert string to concept12
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Vocabulary Explorer
Search and browse vocabularies
Configure
Vocabularies
MappingsBased on Information Retrieval techniques
Matching mechanismsRanking results
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http://explicator.dcs.gla.ac.uk/WebVocabularyExplorer
/Slide15
Vocabulary Explorer ScreenshotSlide16
Vocabulary Explorer ScreenshotSlide17
Vocabulary Explorer ScreenshotSlide18
Vocabulary Explorer ScreenshotSlide19
Conclusions
Vocabularies improve search
Remove ambiguity
Increase precision and recall
Enable
Reasoning about relevanceFaceted browsingProvided tools for working with vocabulariesReliable search from keyword string to vocabulary termExploration of vocabulariesMapping terms across vocabularies
Future WorkProvide a string to concept transformation serviceImprove multi-vocabulary ranking results18
5 November 2008ADASS - Vocabularies in the VOSlide20
Practical Semantic Astronomy 2009
2-5 March 2009
Glasgow, UK
http://www.dcs.gla.ac.uk/workshops/semast09/