Olaf Beyersdorff Arne Meier Michael Thomas Heribert Vollmer The Complexity of Reasoning for Fragments of Default Logic. 51-64 2009 SAT http://dx.doi.org/10.1007/978-3-642-02777-2_7 conf/sat/2009 db/conf/sat/sat2009.html#BeyersdorffMTV09