1. Essentials of the Topic Maps Reference Model (TMRM) Patrick Durusau Snowfall Software Steve Newcomb Coolheads Consulting

2. Basic Principles One subject – Many Identifications No one identification is privileged A single subject representative can contain multiple, independent identifications of the represented subject Ex: TMDM: Set of subject identifiers Identity of a subject is divorced from the identity of its representative

3. Basic Constructs Subject Proxies (proxies) –Composed of properties (key/value pairs) –No restrictions on values –One restriction on keys (see next line) All keys are labels and every proxy has a unique label Result is that a key is always a label for a proxy (enables introspection)

4. Why Introspection? GTE merged 40 databases with 27,000 different elements Est. time without original authors, 12 person years Reason? No introspection of the element names (no where to look) No guarantee of useful introspection, but the mechanism is present

5. Why Introspection? II If no introspection, how to determine if merging should occur if keys are different? Recall all subjects can have multiple identifications Includes subjects represented by proxies whose labels appear as keys Can add identifications to those proxies

6. Primitive Navigation Define sub (subclass of) and isa (instance of) Four primitive navigation operators –All the keys of a proxy –All proxies where a proxy (its label actually) is the value in another proxy –All the values for a key in a proxy –All the proxies with a given value for a particular key

7. Constraints and Merging Constraints: rules for any map m Define: –Application of a constraint to a map –Application of a merging operator between two maps Merging operator (after merging of maps) But, the TMRM doesn’t define any constraints or merging operators

8. Subject Map Legends And what of interchange? Legends are finite sets of constraints governing the interpretation of a map Constraints and hence legends are not constrained by the TMRM TMDM is an example of a legend, rules for merging, etc.

9. Questions?