  We propose a method to evaluate and improve the validity of required
specifications by comparing models from different viewpoints. Inconsistencies
are automatically extracted from the model in which the analyst defines the
service procedure based on the initial requirement; thereafter, the analyst
automatically compares it with a state transition model from the same initial
requirement that has been created by an evaluator who is different from the
analyst. The identified inconsistencies are reported to the analyst to enable
the improvement of the required specifications. We develop a tool for
extraction and comparison and then discuss its effectiveness by applying the
method to a requirements specification example.
