Didn't Warren, James R. and Piekarski, W. not co-author a paper?
Was a paper not not co-authored by James R. Warren and Piekarski, W.?
ASK { ?x <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/00/256> . ?x <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/15/2169> }
<https://dblp.org/pid/00/256> <https://dblp.org/pid/15/2169>