#
Projective lines as groupoids with projection structure

##
Anders Kock

The coordinate projective line over a field is seen as a groupoid with a
further `projection' structure. We investigate conversely to what extent
such an, abstractly given, groupoid may be coordinatized by a suitable
field constructed out of the geometry.

Keywords:
projective geometry, groupoids, geometric algebra

2010 MSC:
18B40, 18D99, 51A25

*Theory and Applications of Categories,*
Vol. 29, 2014,
No. 13, pp 371-388.

Published 2014-07-11.

http://www.tac.mta.ca/tac/volumes/29/13/29-13.pdf

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