Sequentializing Parameterized Programs
This work addresses verification challenges for concurrent systems with unbounded processes, though it is incremental in building on existing sequentialization techniques.
The paper tackles the problem of verifying parameterized concurrent programs by transforming them into sequential programs that preserve reachability and assertions, achieving this with only O(k) copies of shared variables and tracking one thread's local variables at a time.
We exhibit assertion-preserving (reachability preserving) transformations from parameterized concurrent shared-memory programs, under a k-round scheduling of processes, to sequential programs. The salient feature of the sequential program is that it tracks the local variables of only one thread at any point, and uses only O(k) copies of shared variables (it does not use extra counters, not even one counter to keep track of the number of threads). Sequentialization is achieved using the concept of a linear interface that captures the effect an unbounded block of processes have on the shared state in a k-round schedule. Our transformation utilizes linear interfaces to sequentialize the program, and to ensure the sequential program explores only reachable states and preserves local invariants.