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.

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