Class diagram of category and sub-category

Question

I have a simple relationship between product and category I came up with this diagram:

• A product can be assigned to 1 or many categories
• A category can have 0 or many sub-category
• A category can have 0 or 1 parent category
• When you delete a category the sub-categories still exist.

I want to be sure that the diagram has a correct cardinality, especially category to category relation.

Answer 1

Almost correct.

Use roles to clearly identify parent/sub-category along with their multiplicities. The hollow diamond makes it a shared aggregation which means the sub-category lives independent of its parent (else you would use a filled diamond).