Runtime verification based on 4-valued past time LTL

The methodology of runtime verification can verify the system through finding the possible un-safety state trace generated by the running system. This paper proposes the semantic of 4-value past time LTL (Linear Time Logic), which integrates past time LTL with 4-value logic, to improve the verification efficiency when analyzing fault in the traces and the accurate of the results. This paper also shows the semantic and rewrite algorithm of 4-valued past time LTL. The experimental result exhibit the capability of the new semantics to reduce the rewriting steps and to improve the accuracy of the results.