Online Causation Monitoring of Signal Temporal Logic (Artifact)

The artifact package is used to reproduce the experimental results in the paper “Online Causation Monitoring of Signal Temporal Logic”. The abstract of the paper is as follows: Online monitoring is an effective validation approach for hybrid systems that, at runtime, checks whether the (partial) signals of a system satisfy a specification in, e.g., Signal Temporal Logic (STL). The classic STL monitoring is performed by computing a robustness interval that specifies, at each instant, how far the monitored signals are from violating and satisfying the specification. However, since a robustness interval monotonically shrinks during monitoring, classic online monitors may fail in reporting new violations or in precisely describing the system evolution at the current instant. In this paper, we tackle these issues by considering the causation of violation/satisfaction, instead of directly using robustness. We first introduce a Boolean causation monitor that decides whether each instant is relevant to the violation/satisfaction of the specification. We then extend this monitor to a quantitative causation monitor that tells how far an instant is from being relevant to the violation/satisfaction. We further show that classic monitors can be derived from our proposed ones. Experimental results show that the two proposed monitors are able to provide more detailed information about system evolution, without requiring a significantly higher monitoring cost