Sarah Rees

Department of Mathematics University of Newcastle Newcastle NE1 7RU UK +44 (191) 222 7236 Fax: +44 (191) 222 8020 Email: Sarah(DOT)Rees@ncl(DOT)ac(DOT)uk

Office hours for Newcastle students

• Tuesdays, 1100-1200, 1215-1315

until the end of week 12. For appointments at other times, please e-mail me.

Research Interests

• decision problems,
• links between group theory and formal language theory,
• the theory of automatic groups and group combings,
• the language theoretical complexity of the word problem,
• the theoretical and practical development of algorithms in group theory.

Recent articles

• Derek F. Holt and Sarah Rees, Shortlex automaticity and geodesic regularity in Artin groups, to appear in Groups, Complexity and Cryptology.
• Laura Ciobanu, Derek Holt and Sarah Rees, Rapid decay and Baum-Connes for large type Artin groups
• Laura Ciobanu, Derek F. Holt and Sarah Rees, Rapid Decay is Preserved by Graph Products, to appear in Journal of Topology and Analysis.
• Derek F. Holt and Sarah Rees, Generalising some results about right-angled Artin groups to graph products of groups, to appear in Journal of Algebra.
• Derek F. Holt and Sarah Rees, Artin groups of large type are shortlex automatic with regular geodesics, Proc. London Math. Soc 104 (2012) 486--512.
• Derek F. Holt, Sarah Rees, Claas E. R"over, Groups with Context-Free Conjugacy Problems, Int. J. Alg. Comput. 21 (2011) 193-216.
• Derek F. Holt, Sarah Rees and Michael Shapiro, Groups that do and do not have growing context-sensitive word problem, Int. J. Alg. Comput. 18 (2008) 1179-1191.
• Susan Hermiller, Derek Holt and Sarah Rees, Groups whose geodesics are locally testable, Int. J. Alg. Comput. 18 (2008) 911-923.
• Robert H. Gilman, Susan Hermiller, Derek F. Holt and Sarah Rees, A characterisation of virtually free groups, Archiv der Math. 89 (2007) 289--295
• Sarah Rees, The automata that define representations of monomial algebras, Algebras and Representation Theory 11 (2008) 207--214.
• Oliver Payne and Sarah Rees, Computing subgroup presentations using the coherence arguments of McCammond and Wise, J. Alg. 300 (2006) 109--133 (Leedham-Green birthday volume).
• Susan Hermiller, Derek Holt and Sarah Rees, Star-free geodesic languages for groups, Int. J. Alg. Comp. 17 (2007) 329--345.
• Michael Batty, Sam Braunstein, Andrew Duncan and Sarah Rees, Quantum algorithms in group theory, Computational and experimental group theory, 1--62, Contemp. Math., 349, Amer. Math. Soc., Providence, RI, 2004
• Derek F. Holt, Sarah E. Rees, Claas E Röver, and Richard M. Thomas, Groups with context-free co-word problem, Journal of the London Mathematical Society 71 (2005) 643-- 657.
• Sarah Rees, How hard is the word problem?, in Proceedings of Conference for European Women in Mathematics, Varna, Bulgaria, September 2002.
• Derek F.\ Holt and Sarah Rees, Regularity of quasigeodesics in a hyperbolic group,, Internat. J. Alg. Comp. 13 (2003) 585--596.
• Derek F. Holt and Sarah Rees", Solving the word problem in real time, J. London Math. Soc. 63 (2001), 623--639.
• George Havas, Derek F. Holt, P.E.Kenne and Sarah Rees, Some challenging group presentations, J. Austral. Math. Soc. 67 (1999) 137--163.
• Sarah Rees and Leonard H. Soicher, An algorithmic approach to fundamental groups and covers of combinatorial cell complexes, Symb. J. Comput. 29 (2000) 59--77.
• Robert H. Gilman, Derek F. Holt and Sarah Rees, Combing nilpotent and polycyclic groups, Inter. J. Alg. Comput. 9 (1999) 135--155.
• Derek F. Holt and Sarah Rees, Computing with abelian sections of finitely presented groups, J. Algebra 214 (1999) 714--728.
• Sarah Rees, Hairdressing in groups: a survey of combings and formal languages, Geometry and Topology Monographs 1 (1998), The Epstein Birthday Schrift, paper no. 24, pages 493-509
• Sarah Rees, A language theoretic analysis of combings, Contemp. Math. 250, 117--136
• Sarah Rees, Automatic groups associated with word orders other than shortlex, Inter. J. Alg. Comput. 8 (1998), 575--598.

Computer packages

• quotpic, an interactive graphics package to compute and display quotients of a finitely present group, and testisom, which attempts to test for isomorphism between two finitely presented groups, both developed jointly with Derek Holt, and available from the Warwick mathematics ftp-archive. as a joint package isom_quotpic.
• automata, a suite of programs, developed with David Epstein and Derek Holt, to constructively verify that a finitely presented group is shortlex automatic. Now superceded by Derek Holt's kbmag package, which is available from the Warwick mathematics ftp-archive. and contains my own code to test for automaticity with respect to other word orders than shortlex.
• matrix group algorithms developed jointly with Derek Holt, Charles Leedham-Green and Eamonn O'Brien, and now part of the matrix package within the GAP system
• I have contributed to the magnus system, developed by the New York Group Theory Cooperative

Useful links

within Newcastle:-

(some of these are really for my personal use, others are for students)

• my teaching material. Some of this is only accessible from Newcastle machines.
• information about postgraduate study in Newcastle. Potential applicants should look at this. There's a link to the online application system.
• the regulations for single honours programmes in Maths and Stats
• info on joint honours and natural science programmes that involve mathematics and statistics.
• my personal link to Ness (student marks), which has access only by password
• Newcastle's Remote application Service
• Password access to Newcastle's MyImpact system
• School of Maths and Stats Resources for Staff
• Password access to Newcastle's MyProjects system
• the maths and stats wiki, which also has access only by password
• Newcastle myworkplace, useful for expenses claims, which also has access only by password
• classlists for courses at Newcastle, (access only by password)
• the Newcastle e-mail service help page
• secure entry to the the outlook light e-mail service in Newcastle.
• The quantum computing project's wiki.
• results of student questionnaires at Newcastle,

and outside Newcastle:-

• The North British Geometric Group Theory Seminar .
• Access to the web of knowledge system for rating and ranking science journals.
• Alphabetical list of mathematics journals extracted from the Web of Knowledge system on 5th Feb 2013.
• List of mathematics journals ranked by impact factor extracted from the Web of Knowledge system on 5th Feb 2013.
• Top quartile pure maths journals, as defined in Newcastle in March 2013.
• Mathscinet (Bielefeld site)
• Maths e-Print archive (Southampton mirror site) both to submit papers and to pick them up
• Home page for the Magic consortium of UK universities, of which Newcastle is a member, which uses distance learning techniques to supply lecture courses to educate postgraduate students in mathematics and statistics.
• Home page for the London Taught Course Centre (LTCC) , which provides lecture courses for postgraduate students from a consortium of universities in an around London.