Board Thread:General Discussion/@comment-25956839-20160829093743/@comment-26329136-20161017121450

Wikipedia has guidelines on category trees organization. I think this would be useful to make categories meaningful and easier to navigate.

1.

If logical membership of one category implies logical membership of a second (an is-a relationship), then the first category should be made a subcategory (directly or indirectly) of the second. When making one category a subcategory of another, ensure that the members of the subcategory really can be expected (with possibly a few exceptions) to belong to the parent also.

2.

Category chains formed by parent–child relationships should never form closed loops; that is, no category should be contained as a subcategory of one of its own subcategories.

3.

an article should be categorised as low down in the category hierarchy as possible, without duplication in parent categories above it. In other words, a page or category should rarely be placed in both a category and a subcategory or parent category (supercategory) of that category

The current categories are chaotic and there isn't any logic to them. They're not 'category trees' but rather 'category spider webs'; categories and subcategories are seemingly randomly placed everywhere.

Take the current Ferrari category tree, for example.

There are closed loops everywhere. MotorFiesta 1 and Ferrari Heritage Hustle are both subcategories of Ferrari but Ferrari is also a subcategory of both MotorFiesta 1 and Ferrari Heritage Hustle. Closed loops make navigating categories much more difficult.

The subcategories of Ferrari don't make any sense. Subcategories should be subsets of their parent category. Ferrari is currently a subcategory of Manufacturers and logically, this makes sense.

However, 200-225 Speed Cars is a subset of Ferrari and this makes no logical sense since it is not a subset: there are plenty of cars with a top speed of 200-225 MPH that are not made by Ferrari. The same reasoning applies to the Cars that can be purchased with gold, Cars that can be purchased with R$ and the Cars that can be purchased with R$ categories.

Finally, for some reason, Ferrari is a subcategory to itself.

I agree with Michael P about tree categorization. I it would be something like the following (going down the table indicates subcategories):