New York Journal of Mathematics
Volume 23 (2017) 631-654

  

Jacob Shulkin and Wouter van Limbeek

The fundamental theorem of affine geometry on tori

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Published: June 1, 2017
Keywords: Fundamental theorem of geometry, affine torus, collineation, affine automorphism
Subject: Primary 51M04; Secondary 51M05, 51N10, 53A15

Abstract
The classical Fundamental Theorem of Affine Geometry states that for n≧ 2, any bijection of n-dimensional Euclidean space that maps lines to lines (as sets) is given by an affine map. We consider an analogous characterization of affine automorphisms for compact quotients, and establish it for tori: A bijection of an n-dimensional torus (n≧ 2) is affine if and only if it maps lines to lines.

Acknowledgements

This work was completed as part of the REU program at the University of Michigan, for the duration of which JS was supported by NSF grant DMS-1045119.


Author information

Jacob Shulkin:
Department of Mathematics, University of Michigan, Ann Arbor, MI 48109
jshulkin@umich.edu

Wouter van Limbeek:
Department of Mathematics, University of Michigan, Ann Arbor, MI 48109
wouterv@umich.edu