The problem is Given a graph G with kn points, divide it into k pages of n points such that the number of edges between points on different pages is minimal. (I've worked on it with undirected graphs, but I think the basic problem is the same with directed graphs and multigraphs.) I've attacked with branch and bound and linear programming, and it's behaved as an NP-complete program--a 12 point, 4 page problem is solved almost instantly, but a 40 point, 8 page problem took over a day. Then again, those are solutions you use for NP-Complete problems. I see no obvious reduction of 3SAT or Travelling Salesman into it, but it feels like an NP-Complete problem--though that may be because I took a class on solving NP-Complete problems, so hammer and nail.
Is optimal equal-point graph splitting NP-Complete?
cc.complexity theory;graph algorithms
Editing my answer to give a stronger result:The problem is NP-hard for k=2 and called the Minimum Bisection Problem.