Hypertext Model - PowerPoint PPT Presentation

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Hypertext Model

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Hypertext Model. Hypertext is high-level interactive navigational structure ... it lacks underlying data model, navigational plan and consistently designed user ... – PowerPoint PPT presentation

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Title: Hypertext Model


1
Hypertext Model
  • Hypertext is high-level interactive navigational
    structure
  • allows us to browse text non-sequentially on
    computer screen
  • consists of nodes which are correlated by
    directed links in graph structure
  • each node may be text region like a chapter (in
    book), a section (in article), or a Web page

2
Hypertext Model (Cont.)
  • two nodes A and B connected by directed link lAB
    which correlates texts associated with these two
    nodes
  • reader might move to node B while reading text
    associated with node A
  • hypertext link lAB attached to specific string
    inside text for node A
  • such string marked (different color or
    underlined) to indicate presence of underlying
    link
  • if such string clicked, the underlying directed
    link is followed and new text region (for node at
    destination) is displayed on screen

3
Hypertext Model (Cont.)
  • Process of navigating hypertext is traversal of
    directed graph
  • linked nodes of graph represent text nodes that
    are semantically related
  • when hypertext large, user might lose track of
    structure of hypertext
  • lost in hyperspace problem
  • include hypertext map to solve problem
  • directed graph which displays current node
    visited
  • include information on paths traveled so far

4
About the Web
  • Hypertexts provide basis for design of hypertext
    markup language (HTML) and hypertext transfer
    protocol (HTTP) which originated the Web
  • Web not proper hypertext since it lacks
    underlying data model, navigational plan and
    consistently designed user interface
  • Web is pool of (partially) interconnected webs
  • some webs are hypertext others are collection of
    pages designed separately

5
Trends and Research
  • User of Web (frequently) does not know what he
    wants
  • difficulty in formulating request
  • research in advanced user interface highly
    desirable
  • indexes maintained by various Web search engines
    almost disjoint
  • e.g. ten most popular search engines have indexes
    whose intersection is lt 2 of total no. of pages
    indexed
  • research on meta-search engine (fusing rankings
    generated by other search engines) promising
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