Transforming Provenance Using Redaction ◾ 153
e transformed G
q
would now be
<med:Doc_1_4><opm:WasDerivedFrom><_:A1>
<med:Doc_1_4><opm:WasGeneratedBy><med:Results_1_1>
<med:Results_1_1><opm:WasControlledBy><med:Surgeon_1_1>
<med:HeartSurgery1_1><opm:WasControlledBy><med:Physician_1_3>
<med:HeartSurgery1_1><opm:WasControlledBy><med:Surgeon_1_1>
<med:HeartSurgery1_1><opm:Used><_:A1>
10.2.2 Valid Provenance Graph
A graph rewriting system should be capable of specifying under what conditions a
graph manipulation operation is valid. e embedding instructions normally con-
tain a fair amount of information and are usually very flexible. erefore, allowing
the policy designer to specify the embeddings may become error-prone. e OPM
nomenclature places res ...