Expanding the Notion of Links DeRose, S.J. Expanding the Notion of Links. In Proceedings of Hypertext ‘89 (Nov. 5-8, Pittsburgh, PA). ACM, New York, 1989, pp

Scholarly Texts Natural language texts Consist of more than one structure A logical or linguistic structure which is most important Units are chapters, paragraphs and sentences A physical of layout structure Units are pages and lines Though both structures are hierarchical they cannot be reconciled into a single hierarchy

Scholarly Texts These differing hierarchies within a document pose a problem for many hypertexts systems as: Most only support one hierarchy Some do not support hierarchies at all and are free form missing important aspects of the document

Ancient Documents Ancient documents often have more additional structures Some are hierarchical Some reflect the decisions of textual scholars May have formal naming schemes In order to link to main structures in the document May have many versions

Ancient Documents May have many versions Created through repeated copying In some cases version may be due to editing Versions may not: Be sequential Parent and child version of the document may not be able to be identified Versions may have many successors or many sources

Translations Translation further muddle a complicated problem A translation has the same structure and meaning as the original document Contains none of the same content and the word and character level Often needs to be viewed in conjuntion with the original document

Literature Literature in nature differs greatly from technical material Requires deeper interpretive skills Manuals and reference tend to be explicit in mature Novels requires exploration May require on board dictionaries and other aids Requires special tools for locating passages when skimming is not possible

Taxonomy of Links All of this information implies that links have a more complicated design and theoretical issues that at first glance Links must differ not just in structure, but purpose, function and implementation The author suggests hypertext which is reflective of the taxonomic structure itself The following structure was designed to illustrate the capabilities of a system

Extensional Links 1: Extensional Links Idiosyncratic in nature, tying different parts of the system together in unpredictable ways. Stored individually 1A: Relational Links Connect single links together, by writing locations Distinguishing feature is that each the two ends of the link is one conceptual unit, not many. 1A1: Associative Links 1A2: Annotational Links

Extensional Links 1A1: Associative Links Is an entirely unpredictable link Since they link arbitrary parts of documents they cannot be replaced by retrieval algorithms The stock and trade of hypertext Users must be able to create on the fly Usually labeled according to type Being able to coin new types is important for future developments Lack of standardization can prove problematic if users choose their own label type Suggests that user be able to add a sub-type to an existing taxonomy

Extensional Links 1A1: Associative Links Differs from associative link as one of it’s ends is predictable The existence of a link from each of a class of locations is predictable but the target of the link is not Similar to isomorphic links Represent connections from portions of text to information about that text Originate form low level elements Words Could be attached to every word of a text Should be invisible until needed if this is the case

Extensional Links 1B: Inclusion Links Links that connect one originating link to many target locations Represent super-ordinate/sub-ordinate relationships 1B1: Sequential Links Has multiple ordered target locations Paths are an example It should be possible to associate a path with a given location Most important feature is the s-r link (structure representing) Represents aspects of document structure commonly encoded in descriptive markup Paragraphs, block quotes etc

Extensional Links 1B1: Sequential Links s-r links provide a basis for representing text in linear form when needed Require specialized display For instance being traversed automatically in order as the user scrolls s-r links express many useful standard hierarchies By assisting in generating useful links between related structural elements Perform more effective retrieval Help to prevent anomalous documents s-r links generally link to other s-r links The set of s-r link types is fairly constrained

Extensional Links 1B2: Taxonomic Links A link that leads to multiple target locations, but does not impose an order on them Associate lists of properties with particular document elements Connect related groups of data in a lexicon, such as cross references between words Similar to annotational links but usually originate form higher level elements

Intensional Links 2: Intensional Links Follow strictly from the structure and content of the documents they link, they do not need to be stored one by one in the system The destination of intensional links is defined by some function that finds a desired end (rather than a list of known ends) Unidirectional May also have multiple ends.

Intensional Links 2A: Vocative Links Called this because they invike a particular document element by name Reference work use element names suh as a dictionary using a main entry word, or other elements like a chapter of figure specification 2A1: Implicit Links A vocative link which exists because the target element’s name appears inside the content of the source document Example- Dictionary look up Too many links to store explicitly Standard reference methods constitute a second type of implicit link Matt 1:10 - Communicate some sort of indication of destination Bibliographical references constitute a third type of implicit link see chapter 10 - such cross reference function as implicit links

Intensional Links 2A2: Isomorphic Links A vocative link that exists because the target element’s name appears as an element name in the source document (as opposed to content) Most useful where documents share most or all of their logical structure Includes connecting and corresponding elements so users can make comparisons and relate them Example comparing Bibles Tie like named NOT like positioned items together

Intensional Links 2B: Retrieval Links Similar to vocative links however differ in that Find target by content (or content structure and name) not just by formal name Invokes a process to search part of the system for something Retrieval links originate at particular locations not globally List of locations found by the process associated with retrieval constitutes the destination, meaning the destination may change over time.