Categories can include other categories as evidence: when a document is assigned to one category, CIS server can use that assignment as evidence for a related category. This evidence propagation is done using category links. Like evidence terms, category links have a confidence value, telling CIS server how much to add to the document score for the current category when the document is assigned to the linked category.
For example, you can define a taxonomy with a first level of categories that is product-specific and subcategories for functional areas. To avoid defining evidence terms for the product in the subcategories, you can use the evidence defined for the parent category by setting a category link.
There are three types of category links:
Explicit category links, for which you identify the category to link into the evidence for this category
Parent links, for which CIS links all parent categories of this category into its set of evidence terms
Child links, for which CIS links all children of this category into its set of evidence terms
To include automatically Parent or Child links, configure the category class. If a category belongs to a class where these options are set, the evidence for the category includes these links even though they do not appear in the category definition itself.
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