Oliver Mason

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The study of the stability properties of switched and hybrid systems gives rise to a number of interesting and challenging mathematical problems. The objective of this paper is to outline some of these problems, to review progress made in solving these problems in a number of diverse communities , and to review some problems that remain open. An important(More)
This paper describes an experiment on tagging Romanian using QTAG, a parts-of-speech tagger that has been developed originally for English, but with a clear separation between the (probabilistic) processing engine and the (language specific)resource data. This way, the tagger is usable across various languages as shown by successful experiments on three(More)
A survey of the use of graph theoretical techniques in Biology is presented. In particular, recent work on identifying and modelling the structure of bio-molecular networks is discussed, as well as the application of centrality measures to interaction networks and research on the hierarchical structure of such networks and network motifs. Work on the link(More)
We consider the problem of common linear copositive function existence for positive switched linear systems. In particular, we present a necessary and sufficient condition for the existence of such a function for switched systems with two constituent linear time-invariant (LTI) systems. A number of applications of this result are also given.
In this paper we define strong and weak common quadratic Lyapunov functions (CQLF’s) for sets of linear time-invariant (LTI) systems. We show that the simultaneous existence of a weak CQLF of a special form, and the non-existence of a strong CQLF, for a pair of LTI systems, is characterised by easily verifiable algebraic conditions. These conditions are(More)
It was recently conjectured that the Hurwitz stability of the convex hull of a set of Metzler matrices is a necessary and sufficient condition for the asymptotic stability of the associated switched linear system under arbitrary switching. In this paper we show that: (i) this conjecture is true for systems constructed from a pair of second order Metzler(More)
  • Oliver Mason, Ian Grove-Stephenson, Ian Grove-Stephensen
  • 2002
The Paperless School automarking system utilises a number of novel approaches to address the challenge of providing both summative and formative assessments with little or no human intervention. The Paperless School system is designed primarily for day-to-day, low stakes testing of essay and short-text student inputs. It intentionally sacrifices some degree(More)
In this paper we derive necessary and sufficient conditions for the existence of a common linear co-positive Lyapunov function for a finite set of linear positive systems. Both the state dependent and arbitrary switching cases are considered. Our results reveal an interesting characterisation of “linear” stability for the arbitrary switching case; namely,(More)