We show that it is impossible to design a transactional memory system which ensures parallelism, i.e. transactions do not need to synchronize unless they access the same application objects, while ensuring very little consistency, i.e. a consistency condition, called weak adaptive consistency, introduced here and which is weaker than snapshot isolation,… (More)
Despite the large amount of work on Transactional Memory (TM), little is known about how much liveness it could provide. This paper presents the first formal treatment of the question. We prove that no TM implementation can ensure local progress, the analogous of wait-freedom in the TM context, and we highlight different ways to circumvent the impossibility.
The history of distributed computing is full of trade-offs between safety and liveness. For instance, one of the most celebrated results in the field, namely the impossibility of consensus in an asynchronous system basically says that we cannot devise an algorithm that deterministically ensures consensus agreement and validity (i.e., safety) on the one… (More)
In this paper we consider the supervisory control problem through language equation solving. The equation solving approach allows to deal with more general topologies and to find a largest supervisor which can be used as a reservoir for deriving an optimal controller. We introduce the notions of solutions under partial con-trollability and partial… (More)