Title: Three themes in the work of  Charles Ehresmann:
Local-to-global; Groupoids; Higher dimensions.


Author: Ronald Brown


Author's e-mail address: (Optional)

Author's mailing address: Department of Mathematics, University of
Wales, Bangor, Gwynedd LL57 1UT, UK.

AMS classification number: 01A60,53C29,81Q70,22A22,55P15

Other useful information (such as arXive submission number):

arXive math.DG/0602499 UWB Math Preprint 06.03 

Expansion of an invited talk given to the 7th Conference on the
Geometry and Topology of Manifolds:  The Mathematical Legacy of
Charles Ehresmann,  Bedlewo 8.05.2005-15.05.2005 (Poland).


Abstract: This paper illustrates the themes of the title in terms
of: van Kampen type theorems for the fundamental groupoid;
holonomy and monodromy groupoids; and higher homotopy groupoids.
Interaction with work of the writer is explored.


\footnote{KEYWORDS: Ehresmann, local-to-global; fundamental
groupoid; van Kampen
theorem; holonomy and monodromy; higher homotopy groupoids. \\
MSClass2000:}