  We present an imperative object calculus where types are annotated with
qualifiers for aliasing and mutation control. There are two key novelties with
respect to similar proposals. First, the type system is very expressive.
Notably, it adopts the "recovery" approach, that is, using the type context to
justify strengthening types, greatly improving its power by permitting to
recover uniqueness and immutability properties even in presence of other
references. This is achieved by rules which restrict the use of such other
references in the portion of code which is recovered. Second, execution is
modeled by a non standard operational model, where properties of qualifiers can
be directly expressed on source terms, rather than as invariants on an
auxiliary structure which mimics physical memory. Formally, this is achieved by
the block construct, introducing local variable declarations, which, when
evaluated, play the role of store.
