Department of Computer Science, University of Aarhus, DK 8000 Arhus, Denmark. rlyngsoe@daimi.au.dk|Department of Computer Science, University of Aarhus, DK 8000 Arhus, Denmark. rlyngsoe@daimi.au.dk|Department of Computer Science, University of Aarhus, DK 8000 Arhus, Denmark. rlyngsoe@daimi.au.dk