See: Wikipedia:Category intersection for a more recent proposal.

This is a proposal advocating the implementation of category math feature to the MediaWiki software on the English Wikipedia. Category math feature allows Wikipedians to list categories by intersection, union and subtraction. A typical Wikipedia user could find the intersection of two or more categories to be useful and efficient.

Examples:

The concern for this well favoured top-level concept would be how it would be implemented; how it would affect the performance of the live Wikipedia.

Wikinews have already implemented something like it with meta:DynamicPageList.

The ((child actor birth date)) template automatically categorizes actors into:

actors who are currently children (under 13)
teenaged actors (13 to 19)
former child actors (over 19)


Category math syntax

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What are the actual specifications for the category math syntax?

See also

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