Sarah Rees


Department of Mathematics
University of Newcastle
Newcastle NE1 7RU
UK
 
+44 (191) 208 7236 
Fax:  +44 (191) 208 8020 
Email: 
Sarah(DOT)Rees@ncl(DOT)ac(DOT)uk 

Office hours for Newcastle students
I have office hours in term time for students in my modules,
when I am happy to see students without appointment.
For semester 1 201415 (MAS3202, MAS3217), these are
 Mondays 13301530 and Wednesdays 12001400
in teaching weeks,
except on Monday 6th October when I have a conflicting appointment at 1330,
and so my office hours will start shortly after 1400 (as soon as I can get there.)
For appointments at other times, please email me.
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.
Recent articles
 Laura Ciobanu, Susan Hermiller, Derek Holt, and Sarah Rees,
Conjugacy languages in groups, submitted
for publication.
 Derek F. Holt and Sarah Rees,
Conjugacy in Artin groups of extralarge type, submitted for publication.
 Laura Ciobanu, Derek Holt and Sarah Rees,
Sofic groups: graph products and graphs of groups, to appear in Pac. J. Math.
 Derek F. Holt and Sarah Rees,
Shortlex automaticity and geodesic regularity in Artin groups,
Groups, Complexity and Cryptology 5 (2013) 123.
 Laura Ciobanu, Derek Holt and Sarah Rees,
Rapid decay and BaumConnes for large type Artin groups, to appear in TAMS.
 Laura Ciobanu, Derek F. Holt and Sarah Rees,
Rapid Decay is Preserved by Graph Products,
Journal of Topology and Analysis 5 (2013) 225237.
 Derek F. Holt and Sarah Rees,
Generalising some results about rightangled Artin groups to graph products of groups,
Journal of Algebra 371 (2012) 94104.
 Derek F. Holt and Sarah Rees,
Artin groups of large type are shortlex automatic with regular geodesics,
Proc. London Math. Soc 104 (2012) 486512.
 Derek F. Holt, Sarah Rees, Claas E. Röver,
Groups with ContextFree Conjugacy Problems,
Int. J. Alg. Comput. 21 (2011) 193216.
 Derek F. Holt, Sarah Rees and Michael Shapiro,
Groups that do and do not have growing contextsensitive word problem,
Int. J. Alg. Comput. 18 (2008) 11791191.
 Susan Hermiller, Derek Holt and Sarah Rees,
Groups whose geodesics are locally testable,
Int. J. Alg. Comput. 18 (2008) 911923.
 Robert H. Gilman, Susan Hermiller, Derek F. Holt and Sarah Rees,
A characterisation of virtually free groups,
Archiv der Math. 89 (2007) 289295
 Sarah Rees,
The automata that define representations of monomial algebras,
Algebras and Representation Theory 11 (2008) 207214.
 Oliver Payne and Sarah Rees,
Computing subgroup presentations using
the coherence arguments of McCammond and Wise,
J. Alg. 300 (2006) 109133
(LeedhamGreen birthday volume).
 Susan Hermiller, Derek Holt and Sarah Rees,
Starfree geodesic languages for groups,
Int. J. Alg. Comp. 17 (2007) 329345.
 Michael Batty, Sam Braunstein, Andrew Duncan and Sarah Rees,
Quantum algorithms in group theory,
Computational and experimental group theory, 162, Contemp. Math., 349, Amer. Math. Soc., Providence, RI, 2004
 Derek F. Holt, Sarah E. Rees, Claas E Röver, and Richard M. Thomas,
Groups with contextfree coword 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) 585596.
 Derek F. Holt and Sarah Rees",
Solving the word problem in real time,
J. London Math. Soc. 63 (2001), 623639.
 George Havas, Derek F. Holt, P.E.Kenne and Sarah Rees,
Some challenging group presentations,
J. Austral. Math. Soc. 67 (1999) 137163.
 Sarah Rees and Leonard H. Soicher,
An algorithmic approach to fundamental groups and
covers of combinatorial cell complexes,
Symb. J. Comput. 29 (2000) 5977.
 Robert H. Gilman, Derek F. Holt and Sarah Rees,
Combing nilpotent and polycyclic groups,
Inter. J. Alg. Comput. 9 (1999) 135155.
 Derek F. Holt and Sarah Rees,
Computing with abelian sections of finitely presented groups,
J. Algebra 214 (1999) 714728.
 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 493509
 Sarah Rees,
A language theoretic analysis of combings,
Contemp. Math. 250, 117136
 Sarah Rees,
Automatic groups associated with word orders other than shortlex,
Inter. J. Alg. Comput. 8 (1998), 575598.
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
ftparchive.
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
ftparchive.
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 LeedhamGreen 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)
and outside Newcastle: