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

    Research Interests

    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 theoretical complexity of the word problem,
    • the theoretical and practical development of algorithms in group theory.

    If you'd like to know a little more, more details and a complete list of my publications are available here in postscript format, and also (for those who prefer it) in pdf format. Or you can e-mail me....

    Recent articles

    • Derek F. Holt, Sarah Rees and Michael Shapiro, Groups that do and do not have growing context-sensitive word problem to appear in Int. J. Alg. Comput..
    • Susan Hermiller, Derek Holt and Sarah Rees, Groups whose geodesics are locally testable to appear in Int. J. Alg. Comput..
    • 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.
    • 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.
    • Derek F. Holt and Sarah Rees, Computing with abelian sections of finitely presented groups. J. Algebra 214 (1999) 714--728.

    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.
    • info on joint honours programmes that involve mathematics and statistics.
    • the 2009-2010 regulations for joint honours programmes in the SAgE faculty.
    • my personal link to Ness (student marks), which has access only by password
    • the maths and stats wiki, which also has access only by password
    • classlists for courses at Newcastle, (access only by password)
    • results of student questionnaires at Newcastle, (access only by password)
    • the Newcastle e-mail service help page
    • The quantum computing project's wiki .

    and outside Newcastle:-

    • Mathscinet (Bielefeld site)
    • Maths e-Print archive (Southampton mirror site) both to submit papers and to pick them up
    • The North British Geometric Group Theory Seminar .
    • 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.