We can introduce a NoisyRelation class, similar to a Relation but for
̃r ∈ ̃R. The IRM class, which represents a View in the current code,
would store two maps, one mapping relation names to Relation objects,
and one mapping relation names to NoisyRelation objects. The keys in
these maps would be disjoint. Furthermore, a NoisyRelation in an IRM
may have as its base relation a Relation from another IRM
From the doc:
We can introduce a NoisyRelation class, similar to a Relation but for ̃r ∈ ̃R. The IRM class, which represents a View in the current code, would store two maps, one mapping relation names to Relation objects, and one mapping relation names to NoisyRelation objects. The keys in these maps would be disjoint. Furthermore, a NoisyRelation in an IRM may have as its base relation a Relation from another IRM