1. InterOpMay2007 Ontology of Astronomical Object Types Alexandre RICHARD (INAF) Sébastien DERRIERE (CDS) Andrea PREITE MARTINEZ (INAF)

2. InterOpMay2007 May 17th, 20072 Summary An ontology of object types –What is an ontology? –What's a defined concept? –How to deal with ~ –Present status Use cases –Registry Request Builder –Concept Explorer

3. InterOpMay2007 What's an ontology? a data model of a given domain a repository of knowledge, logically organized, exploitable by a “reasoner” a “formal representation of a conceptualization” “a description of the concepts and relationships that can exist for an agent or a community of agents” generally written “as a set of definitions of formal vocabulary.” The present ontology is: made of defined concepts of astronomical objects formalized using description logics & implemented in OWL 1.1 edited with Protégé and exploited with the Protégé-OWL API

4. InterOpMay2007 What's a defined concept? To define a concept: transform knowledge into relationships and necessary and/or sufficient conditions SN Type Ia: n&sis-a SNTypeI (is-a SN) is-a StellarObjectInDoubleStar hasProgenitor some AccretingWhiteDwarf inhhasVariabilityProcess some SuperNovaExplosion hasProcess some ThermonuclearFusion inhnot (hasAbsorptionSpectralLine has ElementH) n&shasAbsorptionSpectralLine has ElementSi

5. InterOpMay2007 C C1 C2 R1R2 R4R3 Rn componentsmorphology processes measurements Properties N/S? is-a I

6. InterOpMay2007 Dwarf Nova hasMeasurement has VariabilityTimeScale-sevDays- sevMonths hasMeasurement has FluxAmplitudeVariation-GT1 hasMeasurement has Period-0.05-0.5d hasPortion some AccretionDisk is-a CataclysmicVariable –DoubleStar –hasMorphology some Close –hasComponent some WhiteDwarf –hasComponent some ((Dwarf or SubGiant) and LateTypeStar) –hasVariabilityProcess some Explosion

7. InterOpMay2007 How to deal with:...there is often an accretion disk......almost all are observed in the IR... C1 C2 C3 IR hasEmissionIn isEmittedBy all IR sources some are IR sources

8. InterOpMay2007 May 17th, 20078 Ontology Construction Identifying concepts & properties –Total: 263, AstroObj: 175 –26 properties Defining concepts –86 with necessary and sufficient conditions Building the subsumption hierarchy –Concept hierarchy –Property hierarchy Adding annotations Testing efficiency Consistency check

9. InterOpMay2007 May 17th, 20079 Registry request builder Registry query with the ontology –The resource description in the registry is fuzzy ( content is free) –The queries expressed by the user must be flexible –The ontology of object types is not used to classify individual sources, but to organize the relationships between classes. –It is therefore used to achieve an intelligent recovery of resources related to one object class

10. InterOpMay2007 May 17th, 200710 Concept Explorer Compare a new concept to existing ones Get concepts with given property Explore (browse) knowledge Test consistency