# Help talk:Categories

Are plural or singular names preferred for categories? My guess is plural given that most of them are, but I've seen some exceptions. --barto (talk) 13:28, 28 January 2017 (EST)

- Plural when the object being categorised is plural, singular when there is only one such object. At least, that's the sort of plan. --prime mover (talk) 15:11, 28 January 2017 (EST)

- One is encouraged to expose exceptions to this rule as such. — Lord_Farin (talk) 04:48, 29 January 2017 (EST)

- There's Category:External Direct Product. --barto (talk) 04:56, 29 January 2017 (EST)

- My thinking there may have been along the lines of: "this is a category about the concept of forming the external direct product of... etc." It will be fixed. --prime mover (talk) 05:03, 29 January 2017 (EST)

- ... job done. --prime mover (talk) 05:20, 29 January 2017 (EST)

## How large should categories be?

Reattempting to clarify this after I got no reaction at Talk:Main Page#Policy on keeping categories small. --barto (talk) 17:01, 25 August 2017 (EDT)

- The trouble with writing rules for this stuff is that in cases where the rule would not work, there would be a lot of trouble bending the natural structure out of shape in order to make it fit something arbitrary. --prime mover (talk) 17:45, 25 August 2017 (EDT)

- It's all been done by the pragmatic approach that if a category spreads over 2 pages it's too big. In the early days before sub-specialisation of categories (before we'd really learned how best to utilise MediaWiki) I found myself spending ages searching through a large number of proofs in Group Theory trying to find whether a specific basic result had been covered. So "small is best".

- On the other hand, splitting them down
*too*far will give the opposite problem: it will difficult to find the correct*category*because now they were either nested too deep to make it easy, or there are now more subcategories than can fit on one page (over 200).

- On the other hand, splitting them down

- So an attempt is made to find a comfortable middle ground.

- (The gradual move towards putting multi-proof results into their own category may be a step in the right direction, but this itself bulks up the subcategory count, so I have in mind another template-based idea: a template called "ProofCategory" which puts a given proof page into a category ".../Proofs/(page name)" or something, so a category has just one subcategory for "proofs" which would then not bulk up the subcategory count, and simplifies the page development process. Early days yet.)

- There is one big exception to this: the "Specific Numbers" category. Think about whether you may have an opinion on this. --prime mover (talk) 05:56, 26 August 2017 (EDT)