homepages/26/3910 conf/wollic/KallmeyerO12 conf/cicling/HelbigGO08 conf/icchp/JengeHHO06 conf/gfkl/BiemannO05 journals/ldvf/Osswald04 phd/de/Osswald2002 conf/wcii/Osswald02 journals/entcs/Osswald01