Chris Wensley's Home Page

              Mail:    Dr. C.D. Wensley,
                       School of Computer Science, 
                       Bangor University,
                       Dean Street, Bangor,
                       Gwynedd LL57 1UT, UK.  

             Phone:    01248 382495   
                
             Email:    c.d.wensley@bangor.ac.uk

Research interests

CHDA : Computational Higher-Dimensional Discrete Algebra - particularly for crossed modules, cat1-groups and related structures:
see the Bangor website for share packages for GAP.

Groebner bases and involutive bases in commutative and noncommutative rings:
with postgraduate student Gareth Evans (2002-2005),
whose thesis Noncommutative involutive bases is available at evans.pdf,
and whose mathematics webpage is at: http://www.dilan4.com/maths/index.htm.

Representation theory of the symmetric group; Burnside rings; Combinatorial species; Polya enumeration.

Packages for GAP 4.4

(latest versions : October 2007)

XMod: crossed modules and cat1-groups,
latest version 2.010 (with Murat Alp),
Kan: double coset rewriting systems for fp-groups,
latest version 0.95 (with Anne Heyworth),
IdRel: ogged rewriting and identities among relators,
latest version 2.03 (with Anne Heyworth),
Gpd: groupoids, group graphs and groupoid graphs,
latest version 1.03 (with Emma Moore),

Local organiser for the 19th British Combinatorial Conference which was held in Bangor from June 30th to July 4th, 2003.

Editor of the conference proceedings:

Surveys in Combinatorics, ed. C.D.Wensley, London Math. Soc. Lecture Note Series 307, Cambridge Univ. Press, 2003.

Talks

talk on the CHDA packages at the GAP Authors' Workshop, Braunschweig, September 2007.

Preprints/Publications

Crossed modules and Computational discrete algebra:

07.10, Automorphisms and homotopies of groupoids and crossed modules
(with Murat Alp).
02.09, Crossed complexes, and free crossed resolutions for amalgamated sums and HNN-extensions of groups
(with Ronnie Brown, Tim Porter and Emma Moore),
Georgian Math. J. 9 (2002) 623-644.
02.04, Computation and Homotopical Applications of Induced Crossed Modules
(with Ronnie Brown),
J. Symbolic Comput. 35 (2003) 59-72.
99.07, Logged rewriting and identities among relators
(with Anne Heyworth),
Groups St Andrews 2001 in Oxford, London Math. Soc. Lecture Note Series 304,
eds. C.M. Campbell, E.F. Robertson & G.C. Smith, Cambridge Univ. Press (2003) 256-276.
97.05. Enumeration of cat1-groups of low order
(with Murat Alp),
IJAC 10 (2000) 407-424.
95.03, On finite induced crossed modules, and the homotopy 2-type of mapping cones
(with Ronnie Brown),
Theory and Applications of Categories, 1(3) (1995) 54-71.
95.04, Computing crossed modules induced by an inclusion of a normal subgroup, with applications to homotopy 2-types
(with Ronnie Brown),
Theory and Applications of Categories, 2(1) (1996) 3-16.

Knuth-Bendix rewriting and Groebner bases:

06.16, Complete involutive rewriting systems
(with Gareth Evans)
J. Symbolic Comp. 42 (2007) 1034-1051.
05.07, String-rewriting for double coset systems
(with Ronnie Brown, Neil Ghani & Anne Heyworth)
J. Symbolic Comp. 41 (2006) 573-590.

Endomorphism graphs:

06.04, Graphs of morphisms of graphs
(with Ronnie Brown, Ifor Morris and John Shrimpton)
Elec. J. Combinatorics, A1, 15(1) (2008) 1-28.
99.02, The endomorphism digraph of a simple, reflexive digraph

Burnside rings, combinatorial species, Polya enumeration:

96.04. Enumeration by Stabilizer Class of Patterns with Local Restrictions
(with Ifor Morris),
Elec. J. Combinatorics, R28, 3(1) (1996) 1-13.
91.16, λ-operations in β-rings
(with Ifor Morris),
Math. Proc. Camb. Phil. Soc. 121 (1997) 247-267.
91.15, Cycle indices and subgroup lattices
(with Ifor Morris),
Discrete Mathematics 118 (1993) 173-195.
82.10, Adams operations and λ-operations in beta-rings
(with Ifor Morris),
Discrete Math. 50 (1984) 253-270.
82.08, Computing Adams operations on the Burnside ring of a finite group
(with Griff Morris and Ifor Morris),
J. Reine Angew. Math. 341 (1983) 87-97.

Representation theory of the symmetric group and spinor harmonics:

Orthogonal spinor harmonics, Proc. London Math. Soc. (3) 22 (1971) 294-312.
Analytic Spinor Fields U.W. Bangor Ph.D. thesis (1970).
Analytic spinor fields
(with D.E.Littlewood), Proc. Roy. Soc. Lond. A 313 (1969) 491-507.
Invariant matrices U.W. Bangor M.Sc. dissertation (1967).

Postgraduate supervision

Gareth Evans, Ph.D. Noncommutative involutive bases (2005)
ftp: pdf file: evans.pdf
Robert Rodrigues (2000-2001)
Emma J. Moore, Ph.D. (with R.Brown) Graphs of groups: word computations and free crossed resolutions (2001)
ftp: gzipped postscript file: moore.ps.gz
Anne L. Heyworth, Ph.D. (with R.Brown) Applications of Rewriting Systems and Groebner Bases to Computing Kan Extensions and Identities Among Relations (1998)
ftp: gzipped postscript file: heyworth.ps.gz
Murat Alp, Ph.D. (with R.Brown) GAP, crossed modules, cat1-groups (1997)
ftp: gzipped postscript file: alp.ps.gz
Abdul-Aali J. Mohammad, Ph.D. Burnside rings of finite groups (1990)
Neil H. Greig-Smith, M.Sc. Invariant Theory (1974)

Modules taught during 2007/2008

IDM1015, Mathematics for Software (semester 1, level 1),

Modules taught during 2006/2007

IDM1015, Mathematics for Software (semester 1, level 1),
IDM2015, Automata Theory (semester 1, level 2),
IDM3004, Graphical Algorithms (semester 1, level 3),
IGT3001(IGT4001), Computational Geometry (semester 1, level 3,4),
IAL4013, Groups & Symmetry (semester 2, level 3,4).
IPM4090, MMath Portfolio (semester 1 reading course).

Modules taught during 2005/2006

IDM1015, Mathematics for Software (semester 1, level 1),
IDM2015, Automata Theory (semester 1, level 2),
IMM2001, Mathematical Methods 3 (semester 1, level 2),
IDM3016, Complexity Theory (semester 2, level 2/3),
IDM4005, Combinatorial Structures (semester 2, level 3/4).
IPM4090, MMath Portfolio (semester 1 presentations component; semester 2 reading course).

Modules taught during 2004/2005

IDM1015, Mathematics for Software (semester 1, level 1),
IDM2015, Automata Theory (semester 1, level 2),
IGT3001, Computational Geometry (semester 1, level 3),
IAN1012, Mathematical Analysis 1 (semester 2, level 1),
IAL4013, Groups & Symmetry (semester 2, level 3/4),

Other modules taught in previous years

ICP1024, Algorithm Design (semester 1, level 1),
IAL2035, Numerical Linear Algebra (semester 2, level 2),
IMM3061, Numerical Analysis (semester 1, level 3)
IOR3085, Operational Research 2 (semester 2, level 3).
IDM4030, Polynomials & Computer Algebra (semester 1, level 3/4),

Latest modification to this page: 07/04/08

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