Abstract

Tool interoperability is among the main goals of the international Grand Challenge initiative. In the context of the Verifiable File System mini-challenge put forward by Joshi and Holzmann, our work has been focused on the integration of different formal methods and tools in a tool-chain for modelling and verification. The current paper shows how to adapt such a tool-chain to the task in hands, aiming at reducing tool integration costs. The refinement of an abstract file store model into a journaled (flash) data model catering for wear leveling and recovery from power loss is taken as case study. This shows that refinement steps can be carried out within a shorter, reduced life-cycle where model checking in Alloy goes hand in hand with manual proofs carried out in the (pointfree) algebra of binary relations. This provides ample evidence of the positive impact of Alloy’s lemma ’everything is a relation’ on software verification, in particular in carrying out induction-free proofs about data structures such as finite maps and lists.

Citations