Human-centred analysis of the dependencies within sets of proofs

A failure in safety-critical systems, such as vehicles, aircrafts, etc., may endanger human lives. It is crucial that these system behave correctly, in accordance to their specification and fulfilling all the safety-critical properties defined for them. Safety could be guaranteed through the application of analysis techniques, in the form of formal verification and testing. However, verification of a real-size system means having a large number of lemmas, depending on each other. An update in one lemma might require changes in many other lemmas. It would be inefficient to find the existing dependencies out when the proof process is already running. We present a methodology for analysis of the dependencies between lemmas within the provided set of proofs. The application of this methodology to the Isabelle/HOL theories is supported by a tool. The tool provides a quick automated analysis and easy-to-check representation of the results, as well as allows optimisation of the provided set of proofs.