Name the author who published the paper on Error propagation and has the name William.
Which author named Christmas published the paper on Error propagation?
SELECT DISTINCT ?answer WHERE { <https://dblp.org/rec/conf/bmvc/ChristmasKP96> <https://dblp.org/rdf/schema#authoredBy> ?answer }
<https://dblp.org/rec/conf/bmvc/ChristmasKP96>