On Squashed Designs.
2000 Mathematics Subject Classification: 51E14, 51E30.We propose a method of constructing partial Steiner triple system, which generalizes the representation of the Desargues configuration as a suitable completion of three Veblen configurations. Some classification of the resulting configurations is given and the automorphism groups of configurations of several types are determined.
The cross-ratio in Hjelmslev planes is defined. The cross-ratio in the Hjelmslev plane is independent of the choice of a coordinate system on a line.