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Ian Morris

  Department of Mathematics
Università di Roma Tor Vergata
Via della Ricerca Scientifica
00133 Roma


Who I am:

I was recently a postdoc at the University of Rome Tor Vergata, working on ergodic theory and dynamical systems under the supervision of Professor Carlangelo Liverani. As of January 2012 I am a Lecturer in the Mathematics Department of the University of Surrey; my current staff profile may be found here. The information below will gradually become out of date as time passes.


Who I am not:

The internet is by no means short of people named Ian Morris. In this vein I would like to mention, therefore, that I am not Professor of Classics and History at Stanford University. I am also not Associate Dean for Research and Chair in Pharmacology and Physiology at Hull-York Medical School, although for a few years he and I were simultaneously present at the University of Manchester and occasionally received one another's mail. It in particular goes without saying that I am not an expert on the effects of drugs or radiation on frogs. I am not now and have never been the rabbi of a Reform synagogue in Leeds, and rumours on the part of Scientific Commons that I may at some point have written a dissertation on the use of humour in Midrash Rabbah are sadly also entirely unfounded.


Research:
  1. Entropy for zero-temperature limits of Gibbs-equilibrium states for countable-alphabet subshifts of finite type.
    J. Statist. Phys. 126 (2007) 315-324 (pdf)
  2. A sufficient condition for the subordination principle in ergodic optimization.
    Bull. London Math. Soc. 39 (2007) 214-220 (pdf)
  3. Maximizing measures of generic Hölder continuous potentials have zero entropy.
    Nonlinearity 21 (2008) 993-1000 (pdf)
  4. Approximating the maximum ergodic average via periodic orbits (with David Collier).
    Ergodic Theory Dynam. Systems 28 (2008) 1081-1090 (pdf)
  5. Lyapunov optimizing measures for C1 expanding maps of the circle (with Oliver Jenkinson).
    Ergodic Theory Dynam. Systems 28 (2008) 1849-1860 (pdf)
  6. The Conze-Guivarc'h-Mañé lemma for intermittent maps of the circle.
    Ergodic Theory Dynam. Systems 29 (2009) 1603-1611 (pdf)
  7. Ergodic optimization for generic continuous functions.
    Discrete and Continuous Dynamical Systems 27 (2010) 383-388. (pdf)
  8. Criteria for the stability of the finiteness property and for the uniqueness of Barabanov norms.
    Linear Algebra and its Applications 443 (2010) 1301-1311. (pdf)
  9. A rapidly-converging lower bound for the joint spectral radius via multiplicative ergodic theory.
    Advances in Mathematics 225 (2010) 3425-3445. (pdf)
  10. An explicit counterexample to the Lagarias-Wang finiteness conjecture (with Kevin G. Hare, Nikita Sidorov and Jacques Theys).
    Advances in Mathematics 226 (2011) 4667-4701. (pdf)
  11. The generalised Berger-Wang formula and the spectral radius of linear cocycles.
    Journal of Functional Analysis 262 (2012) 811-824. (pdf)
  12. On a Devil's staircase associated to the joint spectral radii of a family of pairs of matrices (with Nikita Sidorov).
    Journal of the European Mathematical Society, to appear.
  13. Mather sets for sequences of matrices and applications to the study of joint spectral radii.
    Submitted. (pdf)
  14. A new sufficient condition for the uniqueness of Barabanov norms.
    SIAM Journal of Matrix Analysis, to appear. (pdf)
Work in progress:
  1. Joint spectral characteristics of dominated matrix sets.