Reasoning about Knowledge and Strategies under Hierarchical Information

Two distinct semantics have been considered for knowledge in the context of strategic reasoning, depending on whether players know each other's strategy or not. The problem of distributed synthesis for epistemic temporal specifications is known to be undecidable for the latter semantics, already on systems with hierarchical information. However, for the other, uninformed semantics, the problem is decidable on such systems. In this work we generalise this result by introducing an epistemic extension of Strategy Logic with imperfect information. The semantics of knowledge operators is uninformed, and captures agents that can change observation power when they change strategies. We solve the model-checking problem on a class of "hierarchical instances", which provides a solution to a vast class of strategic problems with epistemic temporal specifications on hierarchical systems, such as distributed synthesis or rational synthesis

Software Synthesis is Hard -- and Simple

While the components of distributed hardware systems can reasonably be assumed to be synchronised, this is not the case for the components of distributed software systems. This has a strong impact on the class of synthesis problems for which decision procedures exist: While there is a rich family of distributed systems, including pipelines, chains, and rings, for which the realisability and synthesis problem is decidable if the system components are composed synchronously, it is well known that the asynchronous synthesis problem is only decidable for monolithic systems. From a theoretical point of view, this renders distributed software synthesis undecidable, and one is tempted to conclude that synthesis of asynchronous systems, and hence of software, is much harder than the synthesis of synchronous systems. Taking a more practical approach, however, reveals that bounded synthesis, one of the most promising synthesis techniques, can easily be extended to asynchronous systems. This merits the hope that the promising results from bounded synthesis will carry over to asynchronous systems as well

Synthesis of distributed systems Final report, 1 Sep. 1966 - 31 Aug. 1969

Algorithm for synthesis of distributed systems to solve circuit design problem

Sequential Synthesis of Distributed Controllers for Cascade Interconnected Systems

We consider the problem of designing distributed controllers to ensure passivity of a large-scale interconnection of linear subsystems connected in a cascade topology. The control design process needs to be carried out at the subsystem-level with no direct knowledge of the dynamics of other subsystems in the interconnection. We present a distributed approach to solve this problem, where subsystem-level controllers are locally designed in a sequence starting at one end of the cascade using only the dynamics of the particular subsystem, coupling with the immediately preceding subsystem and limited information from the preceding subsystem in the cascade to ensure passivity of the interconnected system up to that point. We demonstrate that this design framework also allows for new subsystems to be compositionally added to the interconnection without requiring redesign of the pre-existing controllers.Comment: Accepted to appear in the proceedings of the American Control Conference (ACC) 201

Petri Games: Synthesis of Distributed Systems with Causal Memory

We present a new multiplayer game model for the interaction and the flow of information in a distributed system. The players are tokens on a Petri net. As long as the players move in independent parts of the net, they do not know of each other; when they synchronize at a joint transition, each player gets informed of the causal history of the other player. We show that for Petri games with a single environment player and an arbitrary bounded number of system players, deciding the existence of a safety strategy for the system players is EXPTIME-complete.Comment: In Proceedings GandALF 2014, arXiv:1408.556

Synthesis of distributed systems Annual report, 1 Sep. 1967 - 31 Aug. 1968

Synthesis of distributed systems with application to feedback networks for phase shift oscillator

Synthesis of a simple self-stabilizing system

With the increasing importance of distributed systems as a computing paradigm, a systematic approach to their design is needed. Although the area of formal verification has made enormous advances towards this goal, the resulting functionalities are limited to detecting problems in a particular design. By means of a classical example, we illustrate a simple template-based approach to computer-aided design of distributed systems based on leveraging the well-known technique of bounded model checking to the synthesis setting.Comment: In Proceedings SYNT 2014, arXiv:1407.493