Article
Keywords:
Hjelmsev plane over a special local ring; cross-ratio in Hjelmsev plane
Summary:
The cross-ratio in Hjelmslev planes is defined. The cross-ratio in the Hjelmslev plane $H(R)$ is independent of the choice of a coordinate system on a line.
References:
                        
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MR 0365322 | 
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Some combinatorial properties of conics in the Hjelmslev plane. Math. Slovaca 45 (1995), no. 3, 219-226. 
MR 1361814 | 
Zbl 0853.05018