On improving efficiency of model checking through systematically ...

4. PMC does not support logical OR operator on invariants. We cannot also
use AND and NOT to model OR on invariants. Since Nbac employs BDD
structures to store Boolean expressions, text respresentations of those
Boolean expressions are formed by logical AND,OR,NOT operators. The
lack of this support in PMC makes it impossible to obtain an equivalent
PMC model from an Nbac output model.
Since the output Nbac model is already complicated in the sense that it
contains a lot of locations, transitions and Boolean expressions, adding a
number of locations and transitions to the model makes it extremely big
in size. The practical result shows that PMC could not even initialize the
data structure for the Fischer’s protocol consisting of two processes. The
memory usage to initialize that model exceeds 2.2GB. Furthermore, the lack
of support OR logical on invariant prevents us from verifying any systems.
For those reasons, we had to turn our focus to Uppaal, which is more mature
than PMC in terms of functionality.
3.4.2 nbac2uppaal
We also follow strictly the framework described in Section 3.3 to implement
this tool. Figure 3.13 presents the input and output of the tool. The tool
.xml file
.ba file
nbac2uppaal
.q file
Figure 3.13: Input and output of nbac2uppaal
nbac2uppaal generates two file: .xml file and .q file. The .xml file contains
the system model and the .q file contains the property to be verified. We
test the functionality of this tool with a number of models and it works
properly for all cases we have tried it on.
Note that in the resulting Uppaal model, there is no graphical information
of the model because there is no such information in Nbac output
model. Therefore, the model will be poorly placed and routed when we view
it using the GUI version of Uppaal especially when the model contains too
many items.
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