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- Dan Tufis, Oliver Mason
- 1998

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)

- Robert Shorten, Fabian R. Wirth, Oliver Mason, Kai Wulff, Christopher K. King
- SIAM Review
- 2007

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)

- R. N. Shorten, O. Mason, F. O’Cairbre, P. Curran
- 2003

We present a result on the existence of a common quadratic Lyapunov function for a pair of linear time-invariant systems. We show that this result charac-terises, generalises, and provides new perspectives on several well-known stability results. In particular, new time-domain formulations of the Circle Criterion and Meyer's extension of the KYP lemma are… (More)

- Leonid Gurvits, Robert Shorten, Oliver Mason
- IEEE Trans. Automat. Contr.
- 2007

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)

- Mark Verwoerd, Oliver Mason
- SIAM J. Applied Dynamical Systems
- 2008

We present new necessary and sufficient conditions for the existence of fixed points in a finite system of coupled phase oscillators on a complete graph. We use these conditions to derive bounds on the critical coupling.

- Oliver Mason, Robert Shorten
- IEEE Trans. Automat. Contr.
- 2007

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.

- Robert Shorten, Kumpati S. Narendra, Oliver Mason
- IEEE Trans. Automat. Contr.
- 2003

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)

- Florian Knorn, Oliver Mason, Robert Shorten
- Automatica
- 2009

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)

— We present some new results concerning the stability of positive switched linear systems. In particular, we present a necessary and suf£cient condition for the existence of copositive linear Lyapunov functions for switched systems with two constituent linear time-invariant (LTI) systems. We also extend some recent results on quadratic stability for… (More)

- Mark Verwoerd, Oliver Mason
- SIAM J. Applied Dynamical Systems
- 2009

We extend recent results [50] on the existence of global phase-locked states (GPLS) in the Kuramoto model on a complete graph to the case of a complete bipartite graph. In particular, we prove that, for the Kuramoto model on a complete bipartite graph, the value of the critical coupling coefficient can be determined by solving a system of two nonlinear… (More)