Canadian Mathematical Bulletin: Volume 5 -

On the Fundamental Theorem of Affine Geometry
P. Scherk
Published online by Cambridge University Press:

20 November 2018, pp. 67-69
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The fundamental theorem of affine geometry is an easy corollary of the corresponding projective theorem 2.26 in Artin's Geometric Algebra. However, a simple direct proof based on Lipman's paper [this Bulletin, 4, 265−278] and his axioms 1 and 2 may be of some interest.
Lipman's [desarguian] affine geometry G determined a left linear vector space L={a, b,…} over a skew field F. We wish to construct 1−1 transformations γ of G onto itself such that γ and γ-1 map straight lines onto straight lines preserving parallelism. Designate any point 0 as the origin of G. Multiplying γ with a suitable translation, we may assume γ0=0. Thus γ will then be equivalent to a 1−1 transformation Γ of L onto itself which preserves linear dependence. Since Γ-1 will have the same properties, Γ must also preserve linear independence.

Canadian Mathematical Bulletin