An Analysis of Implementing PVS in SPARK Ada

Abstract

SPARK Ada's support for proofs of correctness make the programming language ideal for implementing a PVS specification. Algorithmically implementing a PVS specification in SPARK Ada allows users to maintain the rigor of PVS in executable code. The goal of such an implementation is to maintain the validity of the proofs showing the specification implements formal requirements specified in PVS as theorems. This then shows the implementation also satisfies those formal requirements. We synthesized portions of NASA's DAIDALUS (Detect and AvoID Alerting Logic for Unmanned Systems) PVS specification into SPARK Ada. To provide confidence in the correspondence between the PVS specification and the SPARK Ada implementation, we designed a formal synthesis process. This process, while currently manual, allows us to have increased confidence that the properties proven to hold for the specification will continue to hold for the implementation.