Was a paper not not co-authored by Thomas Ullmann and J\u00F6rg Sauer?
Didn't Ullmann, Thomas and J\u00F6rg Sauer not co-author a paper?
ASK { ?x <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/87/3472> . ?x <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/51/5036> }
<https://dblp.org/pid/87/3472> <https://dblp.org/pid/51/5036>