Specification of Reactive Hardware/Software Systems - Electronic ...

13.4 Related Results 409
The notion of behaviour-preservation is based on an equivalence relation, called
transformation equivalence. Transformation equivalence is defined on top of the
operational semantics in terms of bisimulations.
Each transformation is:
– mathematically proven correct with respect to transformation equivalence;
– applicable to the full range of POOSL specifications, even those that are
infinite-state;
– applicable during interactive simulation.
The system of transformations is proven to be incomplete. There are always
specifications that are transformation equivalent and that only differ with respect
to their boundaries and channels, but which cannot be transformed into each
other. This incompleteness result is fundamental; it cannot be solved by adding
more transformations. Despite of this, case studies have proven the transformation
system to be applicable in many practical situations.
Next to the incompleteness result described above, another incompleteness result
is proven. For each specification there exists an infinite number of other
specifications that are transformation equivalent, but for which no sequences of
transformations exist that transform the former specification into the latter ones.
This incompleteness result leads us to a fundamental limitation of transformational
design. The choice of an initial specification model determines whether
or not a satisfying implementation model is derivable using transformational design.
Therefore it is important to consider implementation-oriented aspects during
specification. This statement confirms one of the basic ideas of this whole thesis.
13.4 Related Results
Next to the results described in this thesis, there are a number of related results in the
context of our project:
In [Lis94] the POOSL language has been successfully applied to specify the presentation
layer of the OSI reference model.
In [vF96] it is studied how POOSL specifications can be implemented in the C++
programming language [Str92]. A partial mapping from POOSL to C++ is described
in [vF96].
In [Man96] a prototype partial simulator for POOSL is designed.
In [Gei96] the POOSL language has been extended with primitives that allow
the specification of real-time behaviour. A complete formal semantics of these
primitives are also given in [Gei96].
In [Kup96] a compiler is developed that is able to perform a partial translation of
POOSL into PROMELA [Hol93]. PROMELA is the input language for the formal
verification tool SPIN [Hol93].