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Essentials of the Topic Maps Reference Model (TMRM). Patrick Durusau Snowfall Software Steve Newcomb Coolheads Consulting. Basic Principles. One subject – Many Identifications No one identification is privileged
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Essentials of the Topic Maps Reference Model (TMRM) Patrick Durusau Snowfall Software Steve Newcomb Coolheads Consulting
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
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)
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
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
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
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
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.