Heinz wrote:

I would like to combine Categories.

There are two articles Categorie:One and Categorie:Two Whithin another article i would like to get all articles listed, who belong to Categorie:One AND Categorie:Two

Does there allready a solution exist?

I think you're describing the same thing as "Category Math" (http://meta.wikimedia.org/wiki/Category_math) and "Category Intersections". There is an extension (still in development I think, but I'm not sure - I believe it's in use on wikinews) called "Dynamic Page Lists" and I have a rough draft of a special page that includes a UI for browsing through categories (find pages belonging to two or more categories, also see what other categories intersect in those pages - I haven't worked on it for awhile, sorry to say, but it works).

Best Regards, Aerik