214 ◾ Secure Data Provenance and Inference Control
expressions. We intend to build constraints over the paths in a graph pattern as a
way of reducing leakages that cause the inference problem. We write code that can
execute in accordance to the content of a user query. e code can examine various
aspects of a user query, such as the literal text of a triple or triple patterns, and take
immediate actions to ensure the appropriate policy constraints are intact. e fol-
lowing is an example of using regular expressions as part of the BGP of a SELECT
query over a provenance graph, which uses the OPM vocabulary.
{
med:Doc_n_4 gleen:Subgraph("([opm:WasDerivedFrom]*/
[opm:WasGeneratedBy]/
[opm:WasControlledBy])" ?x).
}
is query pattern would give acce