Help:Categories

This pages lists policies and manuals regarding the use of categories, an organizational feature that makes locating pages easier.

Assigning a Category
Each page should reference at least one category, referenced by placing  in the page code. For organizational purposes this is to be added at the very bottom of the page.

So for example, a proof about the properties of sets could go under the category "Set Theory", which is entered as.

A category should not be added when a more specific category applies. For example, Group theory can be omitted when Cyclic Groups is suitable.

Redirects

 * See also Help:Redirects

Creating Category Pages
Sometimes there arises a need for a new category. For example, a contributor could start working on an as-of-yet uncovered field of mathematics. Alternatively, it can be necessary to split a category into several more specific subcategories if it gets too large.

Categories are simply pages that reside in the "Category" namespace, meaning that their title starts with.

Each new category page also needs to be assigned to a category itself. This is done like on normal pages, by adding  to the category page.

For categories of proofs, the universal category is that of Proofs. If a category is a subcategory of something else, then it suffices to add that something else as a category; the MediaWiki architecture will ensure it can be reached from Proofs.

Several conventions on the creation of categories are in place. In due time, these will be explained here, as well as some useful constructs that make managing and creating categories easier. In the mean time, contact one of the ProofWiki sysops for help.

Capitalization
The guidelines for capitalization are the same as for page names. See Help:Page Naming.

Plural versus Singular
Plural when the object being categorized is a collective term for objects; e.g. Category:Limits, Category:Axioms, Category:Cycloids, Category:Cyclotomic Polynomials.

Singular when there is only one such object; e.g. Category:Zeta Function, Category:Group Theory, Category:Algebra (as opposed to Category:Algebras, which is used for actual objects.)

Things like Category:Asymptotic Notation

Example Categories
The way in which example categories are named has recently been changed. Consequently, not all example categories currently follow this new convention. More info on how to add example categories will be added in due time.

Subpages
In order to avoid duplicate entries in page lists, a recent practice is to create a category for each page with many subpages. For example, when a theorem has many proofs, they are all placed in a category, which gets the same name as the main page on which the subpages are transcluded.

Other Categories

 * Definition Equivalences: see Help:Multiple Definitions
 * Category:Proofs by Contradiction: see Help:Proofs by Contradiction
 * Category:Proofs by Induction: see Help:Proofs by Induction
 * Category:Search Convenience: see Help:Redirects § Accented Characters
 * Category:Landmark Pages