  Provenance metadata can be valuable in data sharing settings, where it can be
used to help data consumers form judgements regarding the reliability of the
data produced by third parties. However, some parts of provenance may be
sensitive, requiring access control, or they may need to be simplified for the
intended audience. Both these issues can be addressed by a single mechanism for
creating abstractions over provenance, coupled with a policy model to drive the
abstraction. Such mechanism, which we refer to as abstraction by grouping,
simultaneously achieves partial disclosure of provenance, and facilitates its
consumption. In this paper we introduce a formal foundation for this type of
abstraction, grounded in the W3C PROV model; describe the associated policy
model; and briefly present its implementation, the Provabs tool for interactive
experimentation with policies and abstractions.
