Certainly Unsupervisable States

This paper proposes an abstraction method for compositional synthesis. Synthesis is a method to automatically compute a control program or supervisor that restricts the behaviour of a given system to ensure safety and liveness. Compositional synthesis uses repeated abstraction and simplification to combat the state-space explosion problem for large systems. The abstraction method proposed in this paper finds and removes the so-called certainly unsupervisable states. By removing these states at an early stage, the final state space can be reduced substantially. The paper describes an algorithm with cubic time complexity to compute the largest possible set of removable states. A practical example demonstrates the feasibility of the method to solve real-world problems

On Conditional Decomposability

The requirement of a language to be conditionally decomposable is imposed on a specification language in the coordination supervisory control framework of discrete-event systems. In this paper, we present a polynomial-time algorithm for the verification whether a language is conditionally decomposable with respect to given alphabets. Moreover, we also present a polynomial-time algorithm to extend the common alphabet so that the language becomes conditionally decomposable. A relationship of conditional decomposability to nonblockingness of modular discrete-event systems is also discussed in this paper in the general settings. It is shown that conditional decomposability is a weaker condition than nonblockingness.Comment: A few minor correction

Compositional nonblocking verification with always enabled events and selfloop-only events

This paper proposes to improve compositional nonblocking verification through the use of always enabled and selfloop-only events. Compositional verification involves abstraction to simplify parts of a system during verification. Normally, this abstraction is based on the set of events not used in the remainder of the system, i.e., in the part of the system not being simplified. Here, it is proposed to exploit more knowledge about the system and abstract events even though they are used in the remainder of the system. Abstraction rules from previous work are generalised, and experimental results demonstrate the applicability of the resulting algorithm to verify several industrial-scale discrete event system models, while achieving better state-space reduction than before

The UK guidelines for the use of desmopressin in patients with von Willebrand's disease. Von Willebrand Working Party of the United Kingdom Haemophilia Centre Director's Organization

A document entitled Guidelines for the Diagnosis and management of von Willebrand's Disease was produced by the von Willebrand Working Party of the United Kingdom Haemophilia Centre Directors' Organization. Under the chairmanship of Dr Beverley Hunt, an independent board of haematologists and anaesthesiologists reviewed the use of a synthetic vasopressin analogue, desmopressin (DDAVP), in the management of patients with von Willebrand's disease. The Advisory Board considered that production of the guidelines was to be applauded, but that the contraindications for DDAVP were imprecisely defined and may thus be misleading. This paper summarizes the Advisory Board's discussion of the suggestions