Not just numbers on shelves: using the DDC

for information retrievalGordon Dunsire

Presented at the Symposium “Bridging the class(ification) divide: the new DDC languages

and retrieval possibilities”, 27 April 2010, Bibliotheca Alexandrina, Alexandria, Egypt

Overview

“Traditional” uses of the DDCMachine-readability opens up possibilities for

subject-based information retrievalHierarchical and linear browseKeyword searchTerminology services (hub-spoke)Multilingual retrievalSemantic webEDUG IT survey

Traditional use of the DDC

ShelfmarkingShelf location in a linear sequenceNotation can be fitted to a (book) spine

Subject groupingNotation brings similar topics together and keeps

separate topics apart

Collection analysis by subject or disciplineManagement information by subject

Loans, acquisitions, etc.

Digital environment

Notation <> CaptionsNotation in catalogue record can be

(automatically) matched to human-friendly caption(s)

Opposite of classification process, where caption is matched to notation

Sometimes via Relative Index

Length of caption not a limiting factorLength of notation also not limiting

No need to truncate notation

Notation/caption changes (legacy) more easily managed

Information retrieval

Notation hierarchy can be used to display caption hierarchy

Built notation (i.e. added subdivisions) can be parsed to identify facet captionsE.g. Place, time

Keywords can be found inside captionsNotation can be linked to caption variants

Translations of the DDC“Captions” or subject headings outside of the

schedules

Linear browse

Captions listed in alphabetical orderWith or without Relative Index

Already in alphabetical order

Possibility of keyword-in-context (KWIC) or keyword-out-of-context (KWOC) indexesEach significant word in caption rotated to the

front (or extracted) and interfiled in alphabetical order

Possibility of integration with subject headingsOr substitute for headings

Hierarchical browse

Captions and/or notations exposed at one “level” onlyControlled by numeric notation

First digit = level 1; First 2 digits = level 2, etc.

Decimal notation so maximum of 10 topics at each level

User drills-down in hierarchical order from the top (broadest topic)

Or drills-up from specific to generalLevels can be expressed as tag clouds

Topics weighted by notation (3xx, 32x, 321 ...)

Keyword retrieval

Captions included in:DDC keyword indexSubject keyword index

E.g. With subject headings

General keyword indexE.g. With titles, notes, etc.

DDC caption terminology distinct from other major subject heading schemesAlternative terms (and spellings)

DDC caption: “Acquisition through exchange, gift, deposit”

LCSH: “Book donations” [neither term in Relative Index]

Terminology services (1)

Captions, headings, terms from any scheme can be “classified” by DDCi.e. Assigned a DDC notation

Notation becomes a bridge or link between headings from different schemesHub-and-spoke, with DDC as the hub and each

different scheme as a spokeMore efficient that one-one mappings between

headingsCombinatorial explosion

3 schemes > 3 mappings4 schemes > 6 mappings ...

Terminology services (2)

Hub (i.e. DDC notation) is transparent to userTerm A > DDC notation < Term B

Term A <> Term B

Approach used by High-Level Thesaurus (HILT) projectSuccessful, but scalability an issue

Even though more efficient that Term-Term approach

Scalability might be more achievable in a distributed environment

i.e. Semantic Web

Translations

Caption to caption translationEnglish caption <> Arabic captionBut notation is common, and language-free

Non-English translation is similar to non-DDC topic/subject heading schemeIntrinsic hub-spoke architecture

Arabic caption <> English caption (= notation) <> German captionArabic caption <> German caption

Translations can be automatically switched“Instance” notation remains the same

DDC and the Semantic Web

OCLC is developing a representation of the DDC in resource description framework (RDF)The basis of the semantic webhttp://dewey.info

Includes notations, captions, notes, and legacy (audited changes)Only DDC Summaries available so far

11 languages including English

Can be added to the linked-data “soup”Distributed processing, development and services

Application Current Planned Possible No

Shelfmarking 27 0 1 5Shelf signing and guiding 23 1 1 8Identifier for online materials 8 3 7 15Statistics and management information 17 3 6 7

Notation browse (linear) 12 3 5 13Notation browse (hierarchical) 8 2 4 19Caption browse (linear) 3 3 5 22Caption browse (hierarchical) 2 3 4 24Caption keyword search 4 2 6 21Caption tag cloud 1 1 7 24

Survey results to 20 Apr 2010

Thank you

G.dunsire@strath.ac.ukEDUG IT (links to applications)

http://www.slainte.org.uk/edugit/

Dewey.info (DDC in RDF)http://dewey.info/