HIQUAL Implementierung eines Systems zur Darstellung von Zeit und Kausalität

Abstract

Hiqual is a language for representation and analysis of modularly constructed hierarchical physical or technical systems. Models are the basic elements. They allow the cause-effect description of elementary systems on both the causal and temporal level. Simple hierarchical systems are described in aggregates. Aggregates combine models on two levels of abstraction. More complex hierarchies are described by means of combined aggregates. The analysis of a model description generates a cyclic graph containing all the possible behavioural sequences of the model. Aggregates are checked to make sure that the different Levels of abstraction describe the same, but more or less abstract behaviour. As every model may have an infinite number of behavioural sequences, these tests are only executed for user selected sequences. The analysis is based upon Allen's temporal relations and his propagation algorithm. Hiqual allows to deduce causal relations among events belonging to different models and to find dead-locks caused by inconsistencies. The present paper describes the implementation and mentions those problems that did not find a satisfactory solution, i.e. the representation of inequalities and discontinuous values, and the computational complexity of the analysis.