Figure 2.

Possible valid models for a 45° problem are depicted as 1, 2, 3, and 4. Possible valid models for a 90° problem are depicted as 5, 6, and 7. The models 1, 4, 5, and 7 are termed distorted models (DM) because the distances between the entities vary a lot from each other. The models 2 and 6 have equal distances and are termed equal-distance models (EDM). The model 3 is termed cardinal model (CM) because the to-be-inferred relation corresponds to one of the main cardinal directions, i.e., north, east, south, or west.