Symbolic Abstraction of System Requirements

Because aerospace systems become more and more complex, the pile of documents specifying the requirements for such systems grows continuously. It is obvious that it is not enough just to produce more documents. The expressiveness of system requirements has to be considered as well. However, the ambiguity of natural language generally used to define requirements impedes a manageable growth of system complexities. Therefore, new approaches of abstraction and formalization are needed. In this paper, we describe a semi-automatic implementation of symbolic abstraction by using methods of natural language processing and temporal logic. A graphical presentation of grammatical relations supports the comprehensibility of symbolic abstraction whereas methods defined by the Linear Temporal Logic (LTL) are incorporated to specify the temporal order of requirements. We demonstrate our approach by using exemplary requirements for the ExoMars mission.