Prolog

Hey,

I have a knowledgebase of

movie(untitled_woody_allen_fall_project_2006, 2006).
director(untitled_woody_allen_fall_project_2006, woody_allen).
actor(untitled_woody_allen_fall_project_2006, woody_allen, '').
actor(untitled_woody_allen_fall_project_2006, jody_halse, bouncer).
actor(untitled_woody_allen_fall_project_2006, hugh_jackman, '').
actress(untitled_woody_allen_fall_project_2006, scarlett_johansson, '').
actor(untitled_woody_allen_fall_project_2006, robyn_kerr, '').
actor(untitled_woody_allen_fall_project_2006, kevin_mcnally, mike_tinsley).
actor(untitled_woody_allen_fall_project_2006, ian_mcshane, '').
actor(untitled_woody_allen_fall_project_2006, james_nesbitt, '').
actor(untitled_woody_allen_fall_project_2006, colin_salmon, '').


..
with about 50 other movies as well

How do I find, for example, what actor and director have worked in a movie >n times?

I was thinking

find_actor_director_dup(A,D,n):- len(actor(M,A,_),director(M,D,_))>n.

but I'm that doesn't work and now that I think harder about it it probably shouldn't work...

any ideas?

grep, sed, sort and [spoiler
awk[/spoiler]