1. Datename/org/meeting1 Ontology Usage I.Edward Shaya, Brian Thomas, Zenping Huang, Peter Teuben University of Maryland T HE US N ATIONAL V IRTUAL O BSERVATORY

2. Datename/org/meeting2 Outline Our Project : 2-3 years in development, detail various potentially valuable uses for the VO, tested some sue cases, and developing a framework for use in the VO Outline –What can Ontologies do (that is useful to VO) ? –One use case example we work with –Our Project Technologies

3. Datename/org/meeting3 Basic Ontology Properties * Depicts (Sub)classes, Properties of Classes, Domain and Range of Properties, and Instances. * Subclasses can have restrictions on ranges of properties or additional properties. * Equivalency of Classes, Sameness of Instances, Disjointedness, unions, * Ranges can have Restriction of AllValuesFrom, SomeValuesFrom, and Cardinality

4. Datename/org/meeting4 Obvious Uses Explicit statement of terms and relationships between terms. Similar to a data dictionary but expressed as a directed graph. UCD usage: connect an element with semantic meaning. Applications become aware of isa relations: SBc isa SpiralGalaxy, SpiralGalaxy isa Galaxy, TTauri isa Star. Aid to translating terminology between interest groups.

5. Datename/org/meeting5 No So Obvious Uses Allow for multiple relationships between a pair of Classes. –In XSD, GC/Star means GlobularCluster has Star. But in ontology GC1 hasForeground Star1 GC1 hasBackground Star2 GC1 hasMember Star3 GC1 hasLineOfSite Star4 Or Region Definedby GC1 has Star4

6. Datename/org/meeting6 Not So Obvious Uses (2) Clearly express Catalogs domain Galaxy Milky Way hasMember Messier 3 GlobularCluster Messier 3 hasMember CatalogRow hasMeasurement ProperMotion=pmM3 Star CatalogRow hasMeasurement ProperMotion=pmStars pmStars inInterval pmM3 This is a way to express that the catalog is one of stars that are members of M3 and M3 is in the Milky Way and membership is confirmed by proper motion.

7. Datename/org/meeting7 No So Obvious Uses (3) In tandem with the proper catalog DM it can provides a High Level Query Language: –/MilkyWay//GlobularCluster//Star/hasV elocity//Amplitude/Value > 35 kmPerSec Provides descriptions of transforming between different representations of data. Such as from vector components to amplitude,direction. Ensures valid unit types on each Measurement. i.e. Force must have ForceUnits, Mass must have MassUnits.

8. Datename/org/meeting8 Example Use Case Use-case: Finding the Hubble constant observationally. User wants distances and redshifts (cz) for various galaxy data.

9. Datename/org/meeting9 Ontology Snipet for Use-case

10. Datename/org/meeting10 Example Use Case (2) Step 1: The Setup - specify the problem Galaxy (D, Cz) Step 2: Inference engine does initial search matches: Galaxy (D, Cz) SpiralGalaxy (D, Cz) Galaxy (D tf, Cz) SpiralGalaxy (D tf, Cz) Galaxy (Dceph, Cz)

11. Datename/org/meeting11 Example Use-case (3) Step 3: User makes selection of appropriate objects. F(for this example we follow only one choice): SpiralGalaxy (D tf, Cz) Step 4: Inference engine examines functional ontology to determine if indirect matches exist. Finds that : Galaxy (D tf, Cz ) Galaxy (W 20, I mag, incl)

12. Datename/org/meeting12 Example Use-case (4) Step 5: User presented with the following set of semantic data definitions that can be used to search the VO repositories. SpiralGalaxy (D tf, Cz ) SpiralGalaxy (W 20, I mag, incl)

13. Datename/org/meeting13 Ontology Tech we use (right now) Jena2 (Java) inference engine OWL (W3C standard) for expressing ontologies Protege : lots of consistency checks, visualization, etc to speed ontology construction True Grit

14. Datename/org/meeting14 Summary Started work on ontology approach to data discovery. Limited (so far) piecemeal success. –Working on how a unifying framework should look like. –User GUI interface. Created initial ontology (at http://archive.astro.umd.edu/ont) http://archive.astro.umd.edu/ Not exploiting all the possible uses (yet). Could be aiding discovery better.