What we do in the following example?
I need to combine two words in a phrase: 'professional' and 'holiday'.
There is no adjective 'professional' in Latin or my searching is bad. So I can use the genitive of 'profession' - professionis.
I get: festum (nom.) professionis (gen.), and there is no problem yet (and all agree too that there is no problem in the following combination: - "canis pueri boni"). But if I need to use a verb which governs words by special cases - there seems to be a little trouble.
Professionis is not a true adjective, but this is different from an appositive getitive example (I think) - so what we need to do!?
"Congratulor" takes the accusative, so "festum" must be in this case. But what about professionis?
I can't make them agree.