Topic Maps

1. Topic Maps Custom viewing of data Ashish Mahabal – SPIE ‘02

2. http://www.astro.caltech.edu/~aam/science/topicmaps/ • Roy Williams • George Djorgovski • Robert Brunner

3. Talk plan • Quick reminder of what Topic Maps are • What UCDs are • What a UCD Topic Map is • Where this is leading us

4. What are Topic Maps? • A semantic network over and information pool • A configurable data interconnections viewer • SQL for XML • Data Discovery Tool

5. What do Topic Maps consist of? • Topics (subjects, names, thingies : vertices) • Associations between Topics (relationships : edges) • Occurrences of Topics and of Associations (incidences) • SCOPES!

6. Some examples • NGC 4261 is a Topic (of type “galaxy”) • Galaxy is a Topic (of type “object”) • A “dustlane” is also a topic (more general, of type “galaxy feature”) • “NGC 4261 contains a dustlane” is an Association (of type “object-contains-feature”)

7. NGC 4261 can have multiple occurrences • As an elliptical galaxy • As a radio galaxy (3C 270) • As a dust lane galaxy • As an object in ApJ 1995 Mahabal et al. The different Occurrences appear as different Scopes for the Topic NGC 4261. Indexing is possible on Scopes making Topic Maps more powerful than RDF

8. Where do UCDs come in? • Tables • Columns • Column names Standardization of column names in tables: 4-tier hierarchy with over 1400 UCDs (CDS)

9. UCD Topic Map: Topics • UCDs • Tables • Column names • UCD descriptions • Units • EXTERNAL LINKS

10. UCD Topic Map Associations • UCD occurs in TABLE • UCD corresponds to COLUMN DESCRIPTION • UCD in TABLE has units UNIT • COLUMN DESCRIPTION occurs in TABLE • UCD is associated with UCD DESCRIPTION • UCD is parent of UCD (in the hierarchical structure)

11. UCD Topic Map: Occurrences • In tables • With units • External table links • MORE EXTERNAL LINKS: plots, joins, histograms, statistics

13. Topic Map from single Table • O(10) UCDs • O(10) Column names • O(1) Units • O(100) Associations • O(100) Occurrences

15. The UCD Topic Map uses just the MetaData (the header info) and forms a layer distinct from the data (table) itself

19. What if 100s of tables are used? • Several 100 UCDs – perhaps thousands • Many UCDs are repeated – and that is where the plot gets interesting! Which UCDs are repeated and where?

22. Step 1 in data discovery: Which Table(s) does the UCD of MY interest occur in?

25. What is the UCD Topic Map? • Multiply connected list of UCDs • Multiply connected list of Tables • Multiply connected list of Column names • Multiply connected list of Units • Multiply connected list of {ANY TOPIC YOU HAVE CARED TO DEFINE}

27. … within the 100 Tables TM • Can I merge this IR column with that Xray column? • Do both these catalogs talk about extra-galactic objects? Or would one be good to dientify galactic contaminants? • More interesting to go beyond – YOUR OWN CATALOGS + other catalogs

30. Data discovery is all about asking the right questions! • Can I merge Xray and Radio catalogs? • Which ones? • Do their units match? • What are the parameter ranges? • What is the basic statistics? • Histogram? EXTERNAL LINKS AS TOPICS!

31. Is that it? List all UCDs: instance-of($A,ucd)? Count number of child UCDs: Select $A, count($B) from isParentUCD($A : ucd, $B :ucd)? To order in descending by count: Select $A, count($B) from isParentUCD($A : ucd, $B : ucd) order by $B desc? NO! Direct querying and multiple indexing possible!!

32. What is the UCD Topic Map? • Fully customizable tool for data discovery using metadata!

33. We have made use of catalogs made available at Vizier 100 most frequently used catalogs have been used More specialized UCD Topic Maps are being made General applications of Topic Maps are immense

34. What is out there? • Ontopia’s omnigator • Mondeca • Infoloom • Topicmaps.org • http://www.astro.caltech.edu/~aam/science/topicmaps/