'Correctness of Dataflow

Hello netusers, I've got the following problem: I am writing a compiler in
which it is posssible to 'describe' a program in a sense of dataflow:
There is a initial step, which has following step(s), each with a
condition. In the first, only the initial step is active. When now a
condition holds, the step with that condition is now active, the first one
inactive. There is the possibility of parallel branching and reuniting.
There must be a semantically check of this construction of data flow. As
it is quite similar to a CPM, I have to check if there is a unallowed
combination of steps and transitions (dead locks, steps that are never
reached, ..... ) (sounds hard, so here it is graphical).


Initial Step


/-----\
| |
\-----/
|
+
------------- parallel branching
-------------
|a1) |a2)
| |
| |
/-----\ ------------ alternative branching
| | +b) +c)
\-----/ | |
| | |
| | |
| | |
----------- | parallel uniting
----------- |
| |
                                        | |
                                        | |
                                        ------------------ alternative uniting
|
|
|


The flow goes via a1 and a2, and then either b or c. If it goes via c one
gets a deadlock. And this can only be checked semantically.


Thanks in advance for advice, or bibliographical help, Markus
--
Markus Stroebel RISC Linz, AUSTRIA
--

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