We have covered the basic ideas of topic maps. Like tagging with categories, topic maps is another subject based classification technique. The simplicity of tagging makes it the most popular way to organize information objects. The advanced feature of topic maps makes it more suited for knowledge management. In this section, we will go through features of topic maps that are not covered in the basics section.
Topic names
In topic maps, a topic can be given any number of names. These variant names are alternate forms of the base name. The ability to have more than one name for each topic can be used for many things. In the following example, "Beijing" is the base name. This official spelling is based on the Roman spelling (pinyin). The English spelling is Peking, which was used in English publications up until recent years. "Peiching" and "Pei-ching" are based on the Wade-Giles system which was used for most of the 20th century. When building a topic map, you can include all these names under the "Other names" list. If needed, you can add a scope for each variant name. A scope defines the context of each variant name. A scope itself is a category. Let's add two new categories, "English" and "Wade-Giles" and select "Scope" as its type. If there are categories typed as "Scope", these categories will be shown in the drop down list when you click on the "Scope" column of the "Other names" list.
Scope
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We have just mentioned how to scope a variant name. Scope can also be used in other parts of topic maps. When you form an association by linking one category to another or create an occurrence by linking one category to a reference or note, you can also scope this link. Using the above example, if we found a French Web site about Beijing's history and we want to add it as an occurrence, we can scope this occurrence as "French". First, let's create a category "French" and select "Scope" as its type. Next, create a link from the topic (category) "Beijing" and link it to a French web site. Select "Topic Maps" when creating the link. Select "History" as the link type and select "French" as the link scope.
The purpose of using scope is to add context to topics and the links between topics and resources. Humans are very good at dealing with context. When we read the word "Salsa", we immediately can tell whether it means the Salsa dance or Salsa sauce. When building topic maps, we need to add this context if it is needed. |
Association roles
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When linking a topic to another topic, sometimes you need to specify the role each topic plays. For example, if you have two topics "John Smith" and "Ethan Allen",you create a link between them, and the link type is "works for", others may not know who works for who. In such a case, you can add association roles for each topic to indicate what role each topic plays. First, create two categories "Employer" and "Employee" and select "Association Role Type" as its type. When you link the topic "John Smith" to "Ethan Allen", you can select "Employee" as the "Link from Role", and "Employer" as the "Link to Role". |
Subject identity
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When users build many topic maps, the same subject may adopt a different topic name in different topic maps. For example, the same subject "Beijing" may be named "Peking" in one topic map and be named "Beijing" in another one. When the two topic maps are merged, the computer program needs a subject indicator to know "Beijing" and "Peking" represent the same subject. This subject indicator has to be addressable in the form of an URI. |
