The 18th edition of the International Symposium on Formal Methods organized by Formal Methods Europe will take place at the CNAM in Paris this August. A paper on the work being undertaken by the Hi-Lite team on “Maximal and Compositional Pattern-Based Loop Invariants” will be presented there.
Below is the abstract: “We present a novel approach for the automatic generation of inductive loop invariants over loops manipulating arrays. Unlike most existing approaches, it generates invariants containing disjunctions and quantifiers, which are rich enough for proving functional properties over programs which manipulate arrays. Our approach does not require the user to provide initial assertions or postconditions. It proceeds by recognizing through static analysis simple code patterns that respect stability properties on accessed locations, on an intermediate representation of parallel assignments. We associate with each pattern a formula that we prove to be a so-called local invariant, and we give conditions for local invariants to compose an inductive invariant of the complete loop. We also give conditions over invariants to be locally maximal, and we show that some of our pattern invariants are indeed maximal.”