Hibernate version:3.1.3

Hello everybody :

In HQL, is there a possibility to do a join in on 2 entities (classes) without one being member of the other ?

I looked through the Hibernate examples and seems that always the examples have something like "from Product p inner join fetch p.categories"

I only need to show a product having a certain category without having Category a data member of product.

Well, <join> tag would have made the business but it can only join on the primary key of the first table...

Thank you
Lucian