defining entities for description n.
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Defining Entities for Description

Defining Entities for Description

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Defining Entities for Description

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  1. Defining Entities for Description The Bibliographic Universe

  2. Why bother? Why define a set of objects to describe? Can’t we just let everyone tag everything, no matter what it might be?

  3. The utility of limits Free tags don’t specify a descriptor’s context (does the descriptor indicate the resource’s subject? the date of creation? the date of revision? the author? a comment?). By restricting the scope of description through specifying a more specific set of objects, we enable the definition of more specific attributes and more precise description...and thus more relevant results.

  4. Relevance Relevance: a key concept in determining retrieval effectiveness. Are results relevant to a searcher’s need? The basic retrieval measures are precision and recall. • Precision: Of the results retrieved, how many are relevant? • Recall: Of the relevant results in a collection, how many are in the results set? A search with perfect precision and recall means that all the results are relevant, and no relevant resources were not retrieved in the search. In practice, there tends to be a point at which an inverse relationship between precision and recall obtains: a system that delivers more precise results tends to inhibit recall, and so on.

  5. The bibliographic universe The set of resources that we most commonly store, describe, and make accessible in libraries (and other information systems). We might say that a straightforward entity in the bibliographic universe is the book. But when we say book, what exactly do we mean?

  6. Wilson’s bibliographic universe Wilson’s idea of the bibliographic universe involves the following types of related entities: • Works. • Texts. • Exemplars. Bibliographic control involves our ability to manipulate this universe to find the best material for our needs.

  7. Exemplars According to Wilson, an exemplar is a particular “copy” or “performance” in which a specific “sequence of words and auxiliary symbols” is expressed. Exemplars might be: • A particular physical copy of a book. • A recitation of a poem. • The filmed performance of a play.

  8. Texts According to Wilson, a text is the “sequence of words and arbitrary symbols” that an exemplar puts into physical form. While a single text can be expressed in a variety of forms, the text itself is an “abstract entity” without physicality. Examples of texts include: • The sequence of words and symbols that makes up Wilson’s chapter “The Bibliographic Universe.” • The sequence of words and symbols that constitutes the folio version of Macbeth.

  9. Works According to Wilson, the work is a “group or family of texts.” However, the extent of this family is not easy to determine. Examples of works: • “The Bibliographic Universe” and its translation into French (er, if it is a strict translation). • The combined set of editions of the Chicago Manual of Style.

  10. One work or multiple works? • Marianne Moore’s poem “Poetry” (beginning “I, too, dislike it”) was revised multiple times by the author over 40 years, in varying lengths of 30, 29, 13, and 3 lines. • According to my friend Trent, Hans Gabler’s 1984 edition of Ulysses is an “abomination” and not to be dignified as part of the same work.

  11. Why care about works? In some sense the work is the “basic level” of a document, the one that comes most readily to mind. When looking for a document, we may not even know that multiple texts (or versions) exist, but we know that we want Hamlet. If the catalog shows us all the texts and exemplars that make up the work, we can decide which we want. Or we can just pick any exemplar if the distinctions don’t matter.

  12. Non-textual materials in Wilson’s bibliographic universe For Wilson, images and music are not part of the bibliographic universe, although there “is no sharp boundary” between the pictorial and musical universes and the bibliographic one. Wilson makes this distinction on a pragmatic basis, because images and music seem to require different types of attributes than writings. What does it mean for a picture or musical work to have a subject, for example?

  13. What is the work? • Musical performance (or any performance). • Documentary film footage. • Multiple player online games (Megan Winget’s project to archive and preserve such games).

  14. Documents or information? Is the idea of a bibliographic universe outmoded? Should we instead be thinking about the information universe? Wilson says that documents are often useful or interesting in ways that transcend the information they contain.

  15. Functional Requirements for Bibliographic Records (FRBR) FRBR is an entity-relationship model to describe the bibliographic universe, developed by the International Federation of Library Associations (IFLA). FRBR is meant to model a user view of bibliographic entities and be independent of any particular metadata implementation.

  16. FRBR entity-relationship model FRBR entities include works, expressions, manifestations, and items. Chart from Tillet, 2004

  17. FRBR works A work in the FRBR model is similar to the work described by Wilson: “a distinct intellectual or artistic creation.” FRBR examples of works: • All editions of an anatomy textbook are one work. • A Bach organ fugue and an arrangement for chamber orchestra are the same work. • A French movie in its original form and a version with English subtitles (and one dubbed into Japanese) are the same work.

  18. FRBR expressions An expression in FRBR is similar to Wilson’s text: “the intellectual or artistic realization of a work” in a form, be it textual, sound, image, musical notation, whatever. The expression encompasses the intellectual but not the physical form (e.g., typeface and layout are not part of the expression). Examples of expressions: • The score and performances of a quintet. • A German text and its English translation.

  19. FRBR manifestations A manifestation in FRBR is the realization of an expression in a physical medium. The same expression can be embodied in different manifestations. All copies that are produced as part of the same set are the same manifestation. Examples of manifestations: • The same performance of a musical work on CD and on LP (two manifestations, one expression). • The same edition of a newspaper in print and in microform (two manifestations, one expression).

  20. FRBR items An item in FRBR refers to the actual physical copy of a manifestation. Examples of items: • A particular autographed copy of a book. • A particular copy of a musical score in which one page is missing.

  21. User tasks for FRBR entities The FRBR report identifies four tasks that users should be able to accomplish with all the entities: • Find. • Identify. • Select. • Obtain.

  22. Attributes and entities in FRBR Each entity has a different set of attributes. Some attributes are similar: works and expressions both have titles. (The title of a work, under which expressions are grouped, might be Hamlet, but the title of a particular expression might be William Shakespeare’s Hamlet.) Some attributes are completely different. Manifestations have publishers. Works don’t.

  23. Summary • Defining entities enables more specific description of objects and more focused searching and browsing. • The bibliographic universe includes an unclear and contested number of related entities (works, texts, etc.) that can be difficult to concretely define but are still somehow useful. • Especially for non-textual or new media materials, it may be necessary to put significant thought into what constitutes a work.