NP-completeness in the gossip monoid, with Peter Fenner and Mark Kambites.
International Journal of Algebra and Computation, Vol. 28, No. 4 (2018), Pages 653-672. (Preprint available at arXiv:1606.01026.)
 Identities in Upper Triangular Tropical Matrix Semigroups and the Bicyclic Monoid,
with Laure Daviaud and Mark Kambites.
Journal of Algebra, Volume 501 (2018), Pages 503-525. (Preprint version available at arXiv:1612.04219.)
 Linear isomorphisms preserving Green's relations for matrices over semirings,
with Alexander Guterman and Mark Kambites.
Linear Algebra and its Applications, Volume 545 (2018), Pages 1-14. (Preprint available at arXiv:1709.05277.)
 Tropical matrix groups, with Zur Izhakian and Mark Kambites.
Semigroup Forum, 96 (2018) Issue 1, pp 178-196.
 Face monoid actions and tropical hyperplane arrangements, with Mark Kambites.
International Journal of Algebra and Computation 27 (2017), no. 8, 1001-1025.
(Preprint version available at arXiv:1604.03016.)
 The Shortest Identities for Max-Plus Automata with Two States, with Laure Daviaud.
Proc. 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017),
in Leibniz International Proceedings in Informatics (LIPIcs), vol. 83, 48:1-48:13, Kim G. Larsen et. al (eds.), Dagstuhl, Germany, 2017.
 L. G. Kovacs work on Lie powers,
Journal of the Australian Mathematical Society, Volume 102, Issue 1 (2017) pp. 9-19. Special issue dedicated to the memory of Laci Kovacs.
 FP-injectivity of semirings, semigroup rings and Leavitt path algebras, with T. G. Nam,
Communications in Algebra 45 (2017), no. 5, 1893-1906.
 Pure Dimension and Projectivity of Tropical Polytopes, with Zur Izhakian and Mark Kambites.
Advances in Mathematics, 303 (2016), 1236-1263.
(Author accepted manuscript available at arXiv:1106.4525.)
 Idempotent tropical matrices and finite metric spaces, with Mark Kambites,
Advances in Geometry 14 (2014), no. 2, 253-276.
(Preprint version available at arXiv:1203.2480v1.)
 A modular version of Klyachko's theorem on Lie representations of the general linear group,
with R. M. Bryant. Mathematical Proceedings Cambridge Philosophical Society, 153 (2012), 79-98.
(Preprint version available by request.)
 Periodicity of Adams operations on the Green ring of a finite group, with R. M. Bryant.
Journal of Pure and Applied Algebra, 215 (2011), 989-1002.
(Preprint version available at arXiv:0912.2933v1.)
 Free central extensions of groups and modular Lie powers of relation modules, with Ralph Stöhr.
Proceedings of the American Mathematical Society, 138 (2010), 3807-3814.
(Preprint version available by request or via MIMS Eprints:2009.27.)
 Adams operations on the Green ring of a cyclic group of prime-power order, with R. M. Bryant.
Journal of Algebra, 323 (2010), no. 10, 2818-2833.
(Preprint version available at arXiv:0912.1524v1.)
 Free centre-by-nilpotent-by-abelian groups, with Ralph Stöhr,
Bulletin of the London Mathematical Society, 41 (2009), no. 5, 795-803.
(Preprint version available by request or via MIMS Eprints:2008.51.)
 Standard tableaux and Klyachko's Theorem on Lie representations,
Journal of Combinatorial Theory, Series A, 114 (2007), no. 1, 151-158.
(Preprint version available at MIMS Eprints:2005.52.)
 Geometry and algorithms for upper triangular tropical matrix identities, with Ngoc Mai Tran.
Journal of Algebra, to appear. (Preprint available at arXiv:1806.01835 .)
On group actions on free Lie algebras, PhD thesis, Manchester (2007).
Electronic version available at MIMS Eprints:2008.46.
Using tropical mathematics to model ribosome dynamics, with James Hook.
Mathematics Today, Vol. 51, June 2015, 139-141. (David Broomhead memorial issue.)