Combinatorial aspects of root lattices and words

Heuer, Manuela (2010). Combinatorial aspects of root lattices and words. PhD thesis The Open University.



This thesis is concerned with two topics that are of interest for the theory of aperiodic order. In the first part, the similar sublattices and coincidence site lattices of the root lattice A4 are analysed by means of a particular quaternion algebra. Dirichlet series generating functions are derived, which count the number of similar sublattices, respectively coincidence site lattices, of each index.

In the second part, several strategies to derive upper and lower bounds for the entropy of certain sets of powerfree words are presented. In particular, Kolpakov's arguments for the derivation of lower bounds for the entropy of powerfree words are generalised. For several explicit sets we derive very good upper and lower bounds for their entropy. Notably, Kolpakov's lower bounds for the entropy of ternary squarefree, binary cubefree and ternary minimally repetitive words are confirmed exactly.

Viewing alternatives

Download history


Public Attention

Altmetrics from Altmetric

Number of Citations

Citations from Dimensions

Item Actions



  • Item ORO ID
  • 24046
  • Item Type
  • PhD Thesis
  • Project Funding Details
  • Funded Project NameProject IDFunding Body
    Combinatorics of Sequences and Tilings and its ApplicationsEP/D058465/1EPSRC (Engineering and Physical Sciences Research Council)
  • Keywords
  • similar sublattices; coincidence site lattices; root lattice A4; Dirichlet series; entropy; powerfree words
  • Academic Unit or School
  • Faculty of Science, Technology, Engineering and Mathematics (STEM) > Mathematics and Statistics
  • Copyright Holders
  • © 2010 Manuela Heuer
  • Depositing User
  • Manuela Heuer