First order synthesis for data words revisited

We carry on the study of the synthesis problem on data words for fragments of first order logic, and delineate precisely the border between decidability and undecidability

Parameterized verification of publish/subcribe protocols via Infinite-State Model Checking

We apply the Infinite-State Model Checking to formally specify and validate protocol skeletons for distributed systems with asynchronous communication and synchronous access to local data structures. More precisely, we validate the Redis Pub/Sub key-value Server. Redis is based on a publish-subscribe architecture used in Cloud Storage and Internet of Things ecosystems. For the considered protocol, we present a formal specification that combines ideas coming from round-based and shared-memory specification languages. The resulting model is validated via the SMT-based Infinite-state Model Checker Cubicle. In this setting we use unbounded arrays to model (1) arbitrary collections of publishers and subscribers, (2) unbounded shared memory used as a communication media between processes. Our model is validated using the symbolic backward reachability algorithm implemented in the tool. The peculiarity of the algorithm is that, upon termination, the resulting correctness proof is guaranteed to hold for every number of process instances

A multi-paradigm language for reactive synthesis

This paper proposes a language for describing reactive synthesis problems that integrates imperative and declarative elements. The semantics is defined in terms of two-player turn-based infinite games with full information. Currently, synthesis tools accept linear temporal logic (LTL) as input, but this description is less structured and does not facilitate the expression of sequential constraints. This motivates the use of a structured programming language to specify synthesis problems. Transition systems and guarded commands serve as imperative constructs, expressed in a syntax based on that of the modeling language Promela. The syntax allows defining which player controls data and control flow, and separating a program into assumptions and guarantees. These notions are necessary for input to game solvers. The integration of imperative and declarative paradigms allows using the paradigm that is most appropriate for expressing each requirement. The declarative part is expressed in the LTL fragment of generalized reactivity(1), which admits efficient synthesis algorithms, extended with past LTL. The implementation translates Promela to input for the Slugs synthesizer and is written in Python. The AMBA AHB bus case study is revisited and synthesized efficiently, identifying the need to reorder binary decision diagrams during strategy construction, in order to prevent the exponential blowup observed in previous work.Comment: In Proceedings SYNT 2015, arXiv:1602.0078

A unified view of parameterized verification of abstract models of broadcast communication

We give a unified view of different parameterized models of concurrent and distributed systems with broadcast communication based on transition systems. Based on the resulting formal models, we discuss related verification methods and tools based on abstractions and symbolic state exploration