Topic Map subjects

1
Topic Map subjects

• "A subject is anything that can be spoken about
  or conceived of by a human being. In the most
  generic sense, a subject is anything whatsoever,
  regardless of whether it exists or has any other
  specific characteristics, about which anything
  whatsoever may be asserted by any means
  whatsoever. In particular, it is anything on
  which the author of a topic map chooses to
  discourse."
• xtm spec 2.1.1

2
XTM

• See topicmap.org
• A topic is a surrogate for a non-addressable
  subject.
• A non-addressable subject is something that can
  be described but does not have an intrinsic
  electronic address, e.g.
• Robert A. Morris
• UMASS-Boston
• the course named "XML and Data on the Web"
• Robert Morris's red 1991 Honda
• The home of Robert Morris
• The driveway at the home of Robert Morris
• The garage at the home of Robert Morris
• The street in front of the home of Robert Morris

3
XTM reification

• A topic is said to reify the subject. This is a
  similar notion to reification in RDF it makes it
  possible to "talk" (i.e. give controlled XML)
  about the subject.
• Reification means make real. Here it is in the
  sense of giving the subject enough properties to
  have a meaningful electronic "conversation" about
  it.
• Instead of specifying an RDF Statement naming the
  subject, predicate, and object, XTM has a
  first-class object called a topic. That's what
  reifies a subject.

4
Topic Maps

• A topicMap is a collection of one or more topic
  objects, together with some stuff about them,
  such as properties ("characteristics" ) of them
  and relationships between them or between them
  and addressable resources.
• As in RDF, these relationships can themselves be
  reified, i.e. in this case made into topics.

5
Subject identity

• When are two topics really about the same
  subject?
• If the subject is an addressable resource, no
  problem the topics are the same if they reify
  the same URI
• If not, need to provide a subject indicator, an
  addressable resource that uniquely identifies the
  subject.
• If two topics use the same indicator, then by
  definition they are about the same thing.

6
Topic characteristics

• A property that can be asserted about a topic is
  called a topic characteristic
• These are one of
• a topic name
• a topic occurrence (predicates)
• a role played in an association between two
  topics

7
Occurences

• Any information relevant to a topic. Essentially
  descriptive items that are being asserted.
• lt!ELEMENT occurrence ( instanceOf?, scope?, (
  resourceRef resourceData ) ) gt
• instanceOf is class to which occurrence belongs.
  Defaults to a resourceRef defining "published
  data"
• See http//www.topicmaps.org/xtm/1.0/syn-occur
  for syntax

8
Associations

• Undirected multivariate "relation" (i.e. a set)
• examples/XTM/courses.xtm allows an xtm processor
  to output
• The CSCourse Intermediate Computing with Data
  Structures is recommended by the Computing
  Curricula 2001-- STEELMAN DRAFT (August 1, 2001)
  --