The standard approach to the specification of a secure system is to present a (usually state-hased) abstract security model separately from the specification of the system's functional n:quirements, and establishing a correspondence between the two specifications. This complex treatment has resulted in development methods distinct from those usually advocated for general applications. We provid...

Multirelations model computations with both angelic and demonic non-determinism. We extend multirelations to represent finite and infinite computations independently. We derive an approximation order for multirelations assuming only that the endless loop is its least element and that the lattice operations are isotone. We use relations, relation algebra and RelView for representing and calculat...

The hiding operation, crucial in the construction of categories of games and strategies and hence the compositional aspect of game semantics, has a tendency, as a side effect, to remove branches of computation not leading to observable results. Accordingly, games models of programming languages are usually biased towards angelic non-determinism, where branches leading to e.g. divergence are for...

Most transformational linguists would no longer create explicit deep structures. Instead they adopt a surface-tnterpretlve approach. We find deep structures indIspensable for projection into a semantic network. In conjunction wrth a reference architecture based on constraint-posting, they mlnlmlze referential non-determinism% We extend Marcus’ Determm~sm Hypothesis to include rmmed/ate referenc...

The notion of deterministic execution of concurrent systems has appeared in many guises throughout Edward A. Lee’s œuvre, but few really grasp how powerful, important, subtle, and flexible the concept really is. Determinism can be thought of as an abstraction boundary that delineates where control is passed from a system designer to the implementation. This paper surveys some of the many forms ...

In this report we study the proof employed by Miklos Ajtai [Determinism versus Non-Determinism for Linear Time RAMs with Memory Restrictions, 31st Symposium on Theory of Computation (STOC), 1999] when proving a non-trivial lower bound in a general model of computation for the Hamming Distance problem: given n elements decide whether any two of them have “small” Hamming distance. Specifically, A...

Relational program logics are formalisms for specifying and verifying properties about two programs or two runs of the same program. These properties range from correctness of compiler optimizations or equivalence between two implementations of an abstract data type, to properties like non-interference or determinism. Yet the current technology for relational verification remains underdeveloped...

State-machine-based replication is an effective way to increase the availability and dependability of mission-critical applications. However, all practical applications contain some degree of non-determinism. Consequently, ensuring strong replica consistency in the presence of application non-determinism has been one of the biggest challenges in building dependable distributed systems. In this ...

Parallelism is often required for performance. In these situations an excess of non-determinism harmful as it means the program can have several different behaviours or even results. Even in domains such high-performance computing where parallelism crucial performance, computed value should be deterministic. Unfortunately, programs also allows dynamic scheduling tasks, reacting to first task th...