Alex Clark

Professor and Head of Department
Office College House 002
Phone (0116) 252 5670 
Research
My research interests are in dynamical systems, foliations, topology and their interactions.
Recent Research Summary

Minimal Sets and Attractors of Foliations and Dynamical Systems
Minimal sets and attractors often reflect the limiting behaviour of the systems in which they occur. In the recent work New exotic minimal sets from pseudosuspensions of Cantor systems we discover that minimal sets can have unexpectedly complex behaviour by exhibiting the first examples of hereditarily indecomposable minimal sets of smooth systems that occur with positive entropy. Also, in the paper A compact minimal space Y such that its square Y ×Y is not minimal we present the first example of a compact metric space Y that admits a minimal homeomorphism but is such that Y x Y admits no minimal homeomorphism.

Tiling Spaces
The geometry and rates and patterns of recurrence of aperiodic tilings, such as the Penrose tiling, can be studied and better understood by examination of dynamical systems on related topological spaces known as tiling spaces. The dynamics of the tiling spaces have important links with the diffractive properties of quasicrystals with analogous structure. In the paper Small cocycles, fine torus fibrations, and a Z^{2} subshift with neither we find the first examples of tiling spaces that have no small cocycles. This has the important consequence that the formalism of Bratteli diagrams cannot be generally applied in higher dimensional dynamical systems. In The homology core and invariant measures we use positive cones in homology to find new topological invariants for spaces that generalise the classical tiling spaces and relate this invariant to the structure of the space of invariant measures for the associated dynamical system.
Preprints


New exotic minimal sets from pseudosuspensions of Cantor systems (with Jan P. Boroński and P. Oprocha)
 The homology core and invariant measures, (with J. Hunton), preprint.
 Classifying matchbox manifolds, (with S. Hurder and O. Lukina), preprint

Small cocycles, fine torus fibrations, and a Z^{2} subshift with neither, (with L. Sadun), accepted for publication in Annales Henri Poincaré
Complete list of publications
Conferences and Seminars
 Automatic Sequences, Number Theory, and Aperiodic Order
 Workshop on dynamical systems and continuum theory University of Vienna, Austria
 17th Galway Topology Colloquium
 SubTile 2013
 28th Summer Conference on Topology and its Applications
 One Day Ergodic Theory Meetings (LMS Scheme 3 meetings)
 TTT (LMS Scheme 3 meetings)
 British Mathematical Colloquium (Secretary, local coorganiser with John Hunton)
Recent Grants
 PI EPSRC Grant EP/G006377/1, Foliations: solenoids, regularity and ends.
 PI Grant IN2013045 from the Leverhulme Trust for International Network.
Ph D Students
 Ahmed AlHindawe
 Petra Staynova
 Dina Abuzaid; graduated 2016, Lecturer at King Abdulaziz University
 Dan Rust (Contains a link to download Grout), graduated 2016, Currently Post Doc at the University of Bielefeld
 James Walton ; Blog explaining thesis (first 3 years supervised by John Hunton) Currently at Durham University
 Sheila McCann, graduated August 2013, currently an RA in Leicester
Teaching and Seminars
Autumn 2016
Investigations in Mathematics, Second Year Module
Spring 2017
Strange Attraction, Fourth Year Module

Ph D Seminar for Current Students
 Pure Maths Seminar
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Complete List of Publications and Preprints
 New exotic minimal sets from pseudosuspensions of Cantor systems (with Jan P. Boroński and P. Oprocha)
 The homology core and invariant measures, (with J. Hunton), preprint.
 Classifying matchbox manifolds, (with S. Hurder and O. Lukina), preprint.
 Small cocycles, fine torus fibrations, and a Z^{2} subshift with neither, (with L. Sadun), accepted for publication in Annales Henri Poincaré.
 Shape of matchbox manifolds, (with S. Hurder and O. Lukina), Indagationes Math. 25 (2014) pp. 669712

The Schreier continuum and ends, (with R. Fokkink and O. Lukina), Houston Journal of Mathematics 40 (2014), 569599.

Voronoi tessellations for matchbox manifolds (with S. Hurder and O. Lukina), Top. Proc. 41 (2013) pp. 167259.

Homogeneous matchbox manifolds, (with S. Hurder),Trans. Amer. Math. Soc. 365 (2013), 31513191.
 Tiling Spaces, Codimension One Attractors and Shape, (with John Hunton), New York J. of Math. Volume 18 (2012), 765796.

Embedding solenoids in foliations, (with S. Hurder), Topology Appl. 158 (2011), 12491270.

Solenoidal endomorphisms minimize topological entropy (with R. Fokkink), Nonlinearity 22 (2009) 16631671.

Rhombus filtrations and Rauzy algebras (with K. Erdmann and S. Schroll), Bulletin des sciences mathematiques 133, (2009), pp. 5681.

Symbolic codings and algebraic dynamical systems, (with Robbert Fokkink), Top. Appl. 154 (13), (2007), pp. 25212532.

Questions on the dynamics of tilings, Open Problems in Topology II, Elsevier (2007), pp. 463468.

Topological rigidity of semigroups of affine maps (with Robbert Fokkink), Dynamical Systems,22 (2007), pp. 310.

When shape matters: deformations of tiling spaces, (with Lorenzo Sadun), Ergodic Theory & Dynamical Systems, 26 (2006), pp. 6986.

The rotation class of a flow, Topology and its Applications, 152 (2005), pp. 201208.
 On a homoclinic group that is not isomorphic to the character group (with Robbert Fokkink), Qualitative Theory of Dynamical Systems, (2004) Vol. 5, no. 2, pp. 3615.

Embedding Solenoids (with Robbert Fokkink), Fundamenta Mathematicae, 181 , number 2, (2004), pp. 111124.

The linking homomorphism of onedimensional minimal sets, (with Michael Sullivan), Topology and its Applications, 141 (2004), pp. 12545.

The Classification of Tiling Space Flows, Universitatis Iagellonicae Acta Mathematica, XLI, (2003), pp. 4955.

When size matters: subshifts and their related tiling spaces, (with Lorenzo Sadun), Ergodic Theory & Dynamical Systems, 23 (2003), pp. 10434058.

Bihomgeneity of solenoids, (with Robbert Fokkink) Algebraic and Geometric Topology, 2, (2002) pp. 19.

A generalization of Hagopian's theorem and exponents, Topology and its Applications, 117, (2002), pp. 273283.

The Dynamics of Maps of Solenoids Homotopic to the Identity, (pdf) Lecture Notes in Pure and Applied Mathematics, 230, Marcel Dekker, (2002), pp. 127136.

Solenoidalization and denjoids, (pdf) Houston Journal of Mathematics, 26, No. 4, (2000), pp. 661692.

Flows on solenoids are generically not almost periodic, Geometry and Topology in Dynamics, Contemporary Mathematics (AMS), 246 (1999), pp. 5763.

Exponents and almost periodic flows, Topology Proceedings, 24, (1999), pp. 105134.

Linear flows on ksolenoids, Topology and its Applications, 94 (1999), pp. 2749.