Structure of Concept Principal Element
0.A Concept, Car (Conceptual Records)
Topical and/or categorical constructs (tangible or intangible) not otherwise instantiated
<Concept type="collective"> <Entry scheme="LCSH"> <Name>Automobiles</Name> </Entry> </Concept>
The Concept element may be thought of as a source element, since the other Principal Elements represent selected derivative concepts–Place, Time, etc. Concept encompasses both topical subjects ("aboutness") and generic categorical classes ("isness"), which may be instantiated by individual exemplars of another Principal Element.Concepts for classes of tangibles are collective, e.g. the notion of all "Liver" or all "Copper" everywhere. Their specifics, e.g. a single "Liver specimen" in a jar or "Copper sample", are instantiated by one of the "substantive" Principal Element, discussed earlier. Concepts for intangibles may be either collective or specific, with specific ones instantiated by a "notional" Principal Element or by another Concept, since these are also "notional."In XOBIS, proper nouns are often used as an inclusionary criterion for instantiation, while proper adjectives serve an exclusionary role. This was helpful in explaining why specific intangible concepts, such as processes (Krebs cycle), procedures (Heimlich maneuver), diseases (Alzheimer's disease), etc. remain with Concept.
Ironically, Concept began as a careful separation of topics and categories. Users seeking a novel to read, and those seeking information on the novel as a literary form, have quite different aims, despite the concept actually being the same.However, after grappling with redundancy and various conflicts, we realized that these could be delineated more elegantly using the separate Relationships element.Combining of topic with category and segregating selected "notional" Principal Elements greatly reduced complexity while adding structural cohesion. A crisper Concept element predominantly serves as a home for generic concepts and abstract ideas. This simplification may hold promise for development of informational ontologies or taxonomies used in knowledge management.
In XOBIS, the fundamental Relationships element itself represents a special type of concept, with topic and category representing instances of relationships. Thus, a topical subject relationship indicates that a Work is about the topic "Medical Colleges," and a categorical relationship indicates that an Organization is a member of the topical class "Medical Colleges"– with the topic and topical class being the same Concept. The chief problem seems to be that of singular versus plural referencing according to circumstance, discussed below.Non-topical subjects were considered Relationships from the outset, e.g. a Being or an Event serving as the subject of a Work. Coverage of the other Principal Elements and the Relationships section provide further explanation.
Concept has a 'type' attribute with values:abstract, specific, collective, control, and subdivision. The collective aspect is commonly encountered with terms representing form, genre, format, etc., but has been generalized to extend to include other classes, for example, "Artists" as a genre of people or "Banks" as a genre of business.The value subdivision indicates its suitability as a Subdivision value. This is discussed in the Relationships section.Its Entry/Varia may specify a 'scheme' attribute to indicate the Code of a Work controlling its Name, as well as optional 'language' and 'transliteration'.These examples illustrate the differences, distinctions between topical and categorical relationships, and the role of instantiation:
Concept (abstract; top or middle of hierarchy; topical relationships)
Concept (specific, subset of abstract; bottom of hierarchy; topical relationships)
Concept (collective, subset of abstract; topical/category relationships), instantiated as:
|Brand Name Products||Object|
|Congresses ? Conferences ?||Event|
|Fictional Characters ?||Being|
|Phobias||String (if not established as specific Concept)|
|Silver Nitrate||Object (a sample of the chemical)|
Concept (control, subset of collective; categorical relationships only), instantiated as:
|Pending Records ?||<anyPrincipal Element>|
|Suppressed Records ?||<any Principal Element>|
|Subject Heading Schemes ?||Work (probably as authorities)|
|Transliteration Schemes ?||Work (probably as authorities)|
These may occur when the corresponding topic is not desired/established, permitting display to vary from collective, perhaps "Category:" versus "Record Type:". Software could utilize selected values to enforce related functionality, e.g. record suppression.
Concept (subdivision; relationship indicated by subtype), not instantiated.
|administration & dosage||[MeSH]|
|Social life and customs||[LCSH]|
These govern the values that may be used in the Subdivision element, defined primarily to support topical subheadings due to their affinity to Concept. The technique was extended to other Principal Elements to explore coverage of other kinds of subheadings as a transitional strategy.The 'subtype' attribute for Concept has values: general, form, topical, and unspecified to indicate allowed usage, and the Record's ID serves as the value of Subdivision's 'id' attribute, cf. Relationships section below.
Specific entries for the various Principal Elements represented in the second column may have categorical relationships to the paired Concept in the first column. The collective attribute serves to control permitting this Relationship. For example, the Being Loch Ness Monster would have a categorical relationship to the Concept Monsters. The Singular element allows recording a singular version when a concept's Entry is plural in order to reference the substitute in a Relationship or as part of a Qualifier.See Substitute Entries in the Generic Elements section for more on how conditional display is supported.
The XOBIS structure appears sound, but challenges remain in instantiating concepts and understanding the ramifications of its rigor.The feasibility of mapping various conventional subject schemes to the XOBIS structure is unknown.Rather than trying to accommodate specific conventional subject and form/genre schemes, we elected to create a generic model structure on which to investigate related issues. Improvements in various subject thesauri, the emergent emphasis on form/genre terminology, and the emphasis of NLM's Unified Medical Language System on multi-scheme synthesis and logical relationships are encouraging (43).
The XOBIS structure also implies differences from conventional subject schemes when defining concepts, and changes in the formulation of entries for other elements to reflect their instantial, rather than collective, nature. It also differs in some cases from LC's ambiguous headings decisions (44).For a given topic, it is interesting to note variation in terminology for the same concept– often within the same scheme or suite of schemes. Consider the LCSH form subheading (Congresses) versus the subject entry (Congresses and conventions), the Thesaurus of Graphic Materials term (Tombs & sepulchral monuments) versus separate topics (Sepulchral monuments; Tombs) in LCSH, the general material designator (sound recording) versus topic (Sound Recording and reproducing), and the LCSH topical subject (Gods, Hindu) versus qualifier (Hindu deity). Some of this may be due to the recency of form/genre schemes. To fully realize the coherence in XOBIS, such variations would need to be reconciled. To avoid overkill, subsets from a superset could be designated to indicate adherence to a chosen hierarchical level in a particular institution commensurate with its aims and resources. More study is needed.Additional examples of conceptual instantiations appear under each Principal Element below.See also Entry Substitutes under Generic Elements.
Problem cases are succumbing to analysis so far.Although species names sound inherently specific, in XOBIS they represent concepts. Collected specimens constitute instances (Being), and both the genus and species are classes (Concept).The collective nature of scientific names is more obvious when considering ordinary nomenclature.Singular names for a class, e.g. the Whooper Swan, do not affect the distinction. Cf. the Being section.
|Scientific Name||(Common Name)|
|Species:||Cygnus cygnus||(Whooper Swans)|
Named groups of people represent concepts when a group's name employs a common noun in usage. If the group's name uses a proper noun, it is treated as a collective Being. These are considered instantiations of the first type (common noun).Currently, nationalities are included, although they may be thought of as Relationships of a person to a place.At this stage, XOBIS remains flexible in such areas, as the options are policy-related, and do not affect the general structure.
|Ethnic Groups||Asian Americans|
|Iron and Steel Workers||Hopi Indians|
|People with AIDS ?||Portuguese|
The design of XOBIS supports the simpler, and we believe more powerful, post-coordinate approach, relying on reasonably discrete or atomic concepts, with a generalized emphasis on relationships between them.There appears to be a trend in this direction (45). Topical subheadings are relationally subordinate subsets of a given Concept. Consult the Relationships section for how Subdivision attempts to deal with the reality of current practice.Indexing and presentation of this special structure, differing from that of other Relationships, is an implementational matter.
It is useful to look at the formulation of topical subject headings as an exercise in the identification and definition of concepts or entities, followed by their disambiguation or clarification by way of qualification. Coupled with greater emphasis on hierarchical relationships between concepts, such a systematic approach has much to offer in comparison to highly pre-coordinated and/or enumeration-oriented techniques. Instead of a single, fixed arrangement, there is the simplicity of fewer entries with more hits and the added flexibility to present search results sub-arranged by various criteria. Too many LCSH headings have a single hit.The FAST Project (46) offers encouragement in that its faceted approach more closely approximates XOBIS' structural breakdown.Recent changes to Medical Subject Headings (MeSH) introducing concept IDs portend that rigorous relationships similar to those in the UMLS will be supported in the future (43, 47).Further exploration is needed to realize the full potential of more robust and better-coordinated topical vocabularies.