Associations

After having collected our topics we finally can connect them, which is one of the most important aspects within a topic map. The task is now:

• to find meaningful associations between the topics and
• to define the roles played by the topics in the association.

What is a meaningful association?

Topics can have relationships between each other and the trick is to find the most meaningful association. That means, you have to be explicit - to pin it down, to make it clear - which relationship two or more topics have to each other.

Associations can be rather general like:

• is located in
• lives in
• written by
• born in

• is an academic organization within
• requires to have property
• a facility provided by

A simple example for an association could be: bond-uni is located in robina.

Why do we need members and roles?

We need to define roles because someone could interpret: robina is located in bond-uni. To avoid confusion and to make it perfectly clear who is who and who plays which role in the association we use the following scheme:

• the topics involved in the association are called members
• and the members play roles

Connect Topics with Associations

<association>
  <instanceOf>
    <topicRef xlink:href="#is-located-in"/>
  </instanceOf>
  <member>
    <roleSpec><topicRef xlink:href="#building"/></roleSpec>
    <topicRef xlink:href="#bond-uni"/>
  </member>
  <member>
    <roleSpec><topicRef xlink:href="#location"/></roleSpec>
    <topicRef xlink:href="#robina"/>
  </member>
</association>

Note: Every time we introduce a reference to a new topic (topicRef xlink:href), we have to define the topic.

<topic id="is-located-in">
  <baseName>
    <baseNameString>is located in</baseNameString>
  </baseName>
</topic>

<topic id="building">
  <baseName>
    <baseNameString>building</baseNameString>
  </baseName>
</topic>

<topic id="location">
  <baseName>
    <baseNameString>location</baseNameString>
  </baseName>
</topic>

In the same way we can express the fact it-school belongs to bond-uni:

IT School belongs to Bond University

In order to have a meaningful relationship between our members we introduced a new topic is-an-academic-organization-within which is more expressive than a simple belongs-to we also could have used.

<association>
  <instanceOf>
    <topicRef xlink:href="#is-an-academic-organization-within"/>
  </instanceOf>
  <member>
    <roleSpec><topicRef xlink:href="#faculty"/></roleSpec>
    <topicRef xlink:href="#it-school/>
  </member>
  <member>
    <roleSpec><topicRef xlink:href="#university"/></roleSpec>
    <topicRef xlink:href="#bond-uni"/>
  </member>
</association>

As we have seen before, we are again supposed to define our topics which we introduced as we created our association - if we have not already done so. In the example above we referred to faculty and university which we both have already defined in a previous section. Therefore we have only one topic left:

<topic id="is-an-academic-organization-within">
  <baseName>
    <baseNameString>is an academic organization within</baseNameString>
  </baseName>
</topic>

Associations can also connect more than two topics, as the example Gopal is the dean of the Bond IT school shows:

Gopal is the dean of the Bond IT school

While the topic it-school was already defined before we have to create some new ones:

<topic id="gopal">
  <instanceOf><topicRef xlink:href="#person"/></instanceOf>
  <baseName>
    <baseNameString>Gopal Gupta</baseNameString>
  </baseName>  
</topic>

<topic id="person">
  <baseName>
    <baseNameString>person</baseNameString>
  </baseName>
</topic>

<topic id="dean">
  <instanceOf><topicRef hlink:href="#position"/></instanceOf>
  <baseName>
    <baseNameString>dean</baseNameString>
  </baseName>
</topic>

<topic id="position>
  <baseName>
    <baseNameString>position</baseNameString>
  </baseName>
</topic>

in order to create the association properly:

<assocation>
  <instanceOf>
    <topicRef xlink:href="#holds-position-in-organisation"/>
  </instanceOf>
  <member>
    <roleSpec><topicRef xlink:href="#holder"/></roleSpec>
    <topicRef xlink:href="#gopal"/>
  </member>
  <member>
    <roleSpec><topicRef xlink:href="#position"/></roleSpec>
   <topicRef xlink:href="#dean"/>
  </member>
  <member>
    <roleSpec><topicRef xlink:href="#organisation"/></roleSpec>
    <topicRef xlink:href="it-school"/>
  </member>
</association>

Finally, we pay our dues with

<topic id="holder">
  <baseName>
    <baseNameString>position holder</baseNameString>
  </baseName>
</topic>

<topic id="organisation">
  <baseName>
    <baseNameString>organisation</baseNameString>
  </baseName>
</topic>

<topic id="holds-position-in-organisation">
  <baseName>
    <baseNameString>holds position in organisation</baseNameString>
  </baseName>
</topic>

The exact sequence of our declarations of topics and associations does not matter to any system processing the topic map. Topic maps only capture the relative relationship between topics. [ standard]

Our next section gives a more in-depth look into adding resources to topics.