I am a Professor of Pure Mathematics for School of Mathematics, Statistics & Physics at Newcastle University. I work mainly on geometrical, combinatorial and computational aspects of group theory. In particular, I am currently interested in:

• Decision problems
• Links between group theory and formal language theory
• The theory of automatic groups and group combings
• The language of theoretical complexity of the word problem
• The theoretical and practical development of algorithms in group theory

Roles and Responsibilities

• Personal research
• Undergraduate and postgraduate teaching in Newcastle, and supervision of postgraduate students
• Personal tutor of a group of undergraduate students
  
• External examiner of undergraduate and postgraduate degrees
• Refereeing of articles, grant proposals, and membership of panels (member of EPSRC Peer Review College)
  
• Involved in appointments and promotions in universities across the world
• Advisor and organiser of mathematics research conferences
  

Research Interests

Google Scholar

Geometrical, Combinatorial and Computational Group Theory
Decision problems
Links Between Group Theory and Formal Language Theory
Theory of Automatic Groups and Group Combings
Language Theoretical Complexity of the Word Problem
Theoretical and Practical Development of Algorithms in Group Theory

• Ciobanu L, Holt D, Rees S. Equations in groups that are virtually direct products. Journal of Algebra 2020, 545, 88-99.
• Dehornoy P, Holt DF, Rees S. Multifraction reduction IV: Padding and Artin-Tits monoids of sufficiently large type. Journal of Pure and Applied Algebra 2018, 222(12), 4082-4098.
• Ciobanu L, Holt D, Rees s. The generalised word problem in hyperbolic and relatively hyperbolic groups. Journal of Algebra 2018, 516, 149-171.
• Holt DF, Rees S, Rover CE. Groups, languages and automata. Cambridge: Cambridge University Press, 2017.
• Holt DF, Rees S. Some closure results for C-approximable groups. Pacific Journal of Mathematics 2017, 287(2), 393-409.
• Nebe G, Parker R, Rees S. A method for building permutation representations of finitely presented groups. In: Finite Simple Groups: Thirty Years of the Atlas and Beyond. 2016, Princeton University, New Jersey.
• Ciobanu L, Hermiller S, Holt DF, Rees S. Conjugacy languages in groups. Israel Journal of Mathematics 2016, 211(1), 311-347.
• Ciobanu L, Holt DF, Rees S. Rapid decay and Baum-Connes for large type Artin groups. Transactions of the American Mathematical Society 2016, 368(9), 6103-6129.
• Godelle E, Rees S. Rewriting systems in sufficiently large Artin-Tits groups. Journal of Algebra 2016, 466, 284-307.
• Holt DF, Rees S. Conjugacy in Artin groups of extra-large type. Journal of Algebra 2015, 434, 12–26.
• Lawson M, O'Carroll L, Rees S. David Rees 1918-2013. Semigroup Forum 2014, 88(3), 513-522.
• Ciobanu L, Holt DF, Rees S. Sofic groups: graph products and graphs of groups. Pacific Journal of Mathematics 2014, 271(1), 53–64.
• Ciobanu L, Holt DF, Rees S. Rapid decay is preserved by graph products. Journal of Topology and Analysis 2013, 5(2), 225.
• Holt DF, Rees S. Shortlex automaticity and geodesic regularity in Artin groups. Groups Complexity Cryptology 2013, 5(1), 1-23.
• Holt DF, Rees S. Artin groups of large type are shortlex automatic with regular geodesics. Proceedings of the London Mathematical Society 2012, 104(3), 486-512.
• Holt DF, Rees S. Generalising some results about right-angled Artin groups to graph products of groups. Journal of Algebra 2012, 371, 94-104.
• Holt D, Rees S, Roever C. Groups with context-free conjugacy problems. International Journal of Algebra and Computation 2011, 21(1-2), 193-216.
• Batty M, Casaccino A, Duncan AJ, Rees S, Severini S. An application of the Deutsch-Jozsa algorithm to formal languages and the word problem in groups. In: Theory of Quantum Computation, Communication, and Cryptography: Third Workshop (TQC). 2008, Tokyo, Japan: Springer.
• Holt DF, Rees SE, Shapiro M. Groups that do and do not have growing context-sensitive wordproblem. International Journal of Algebra and Computation 2008, 18(7), 1179-1191.
• Hermiller S, Holt D, Rees SE. Groups whose geodesics are locally testable. International Journal of Algebra and Computation 2008, 18(5), 911-923.
• Rees S. The automata that define representations of monomial algebras. Algebras and Representation Theory 2008, 11(3), 207-214.
• Gilman RH, Hermiller S, Holt DF, Rees S. A characterisation of virtually free groups. Archiv der Mathematik 2007, 89(4), 289-295.
• Hermiller S, Holt DF, Rees S. Star-free geodesic languages for groups. International Journal of Algebra and Computation 2007, 17(2), 329-345.
• Payne O, Rees S. Computing subgroup presentations, using the coherence arguments of McCammond and Wise. Journal of Algebra 2006, 300(1), 109-133.
• Holt DF, Rees SE, Röver CE, Thomas RM. Groups with context-free co-word problem. Journal of the London Mathematical Society 2005, 71(3), 643-657.
• Batty M, Braunstein SL, Duncan AJ, Rees S. Quantum algorithms in group theory. In: Computational and Experimental Group Theory. 2004, Baltimore, Maryland, USA: American Mathematical Society.
• Batty M, Braunstein SL, Duncan AJ, Rees SE. Quantum Algorithms in Group Theory. Contemporary Mathematics 2004, 349, 1-62.
• Batty M, Braunstein SL, Duncan A, Rees S. Quantum algorithms in group theory. In: Interactions between Logic, Group Theory and Computer Science. 2003, Maryland, USA: American Mathematical Society.
• Holt DF, Rees S. Regularity of quasigeodesics in a hyperbolic group. International Journal of Algebra and Computation 2003, 13(5), 585-596.
• Rees SE, Holt D. Regularity of Quasigeodesics in a hyperbolic group. International Journal of Algebra and Computation 2003, 13(5), 585-596.
• Rees SE. How hard is the word problem. In: European Women in Mathematics. 2002, Varna, Bulgaria.
• Holt DF, Rees S. Solving the word problem in real time. Journal of the London Mathematical Society 2001, 63(3), 623-639.
• Rees S, Soicher LH. An Algorithmic Approach to Fundamental Groups and Covers of Combinatorial Cell Complexes. Journal of Symbolic Computation 2000, 29(1), 59-77.
• Rees S. A language theoretic analysis of combings. Contemporary Mathematics 1999, 250, 117-136.
• Gilman RH, Holt DF, Rees S. Combing nilpotent and polycyclic groups. International Journal of Algebra and Computation 1999, 9(2), 135-155.
• Holt DF, Rees S. Computing with Abelian sections of finitely presented groups. Journal of Algebra 1999, 214(2), 714-728.
• Holt DF, Rees S. Computing with abelian sections of finitely presentedgroups. Journal of Algebra 1999, 214(2), 714-728.
• Havas G, Holt DF, Kenne PE, Rees S. Some challenging group presentations. Journal of the Australian Mathematics Society 1999, 67(2), 206-213.
• Havas G, Holt DF, Kenne PE, Rees S. Some challenging group presentations. Journal of the Australian Mathematical Society 1999, 67(2), 206-213.
• Havas G, Holt DF, Kenne PE, Rees S. Some challenging group presentations. Journal of the Australian Mathematical Society Series A - Pure Mathematics and Statistics 1999, 67, 206-213.