  Contextual equivalence equate terms that have the same observable behaviour
in any context. A standard contextual equivalence for CCS is the strong barbed
congruence. Configuration structures are a denotational semantics for processes
in which one define equivalences that are more discriminating, i.e. that
distinguish the denotation of terms equated by barbed congruence. Hereditary
history preserving bisimulation (HHPB) is such a relation. We define a strong
back-and-forth barbed congruence on RCCS, a reversible variant of CCS. We show
that the relation induced by the back-and-forth congruence on configuration
structures is equivalent to HHPB, thus providing a contextual characterization
of HHPB.
