Integrating DFT and DRBD Formalizations in HOL4

Dynamic Fault Trees (DFT) and Dynamic Reliability Block Diagrams (DRBD) are two modeling approaches that capture the dynamic failure behavior of engineering systems for their reliability analysis. Recently, two independent higher-order logic (HOL) formalizations of DFT and DRBD algebras have been developed in the HOL4 theorem prover. In this work, we propose to integrate these two modeling approaches for the efficient formal reliability analysis of complex systems by leveraging upon the advantages of each method. The soundness of this integration is provided through a formal proof of equivalence between the DFT and DRBD algebras. We show the efficiency of the proposed integrated formal reliability analysis on a drive-by-wire system as a case study.