In addition to the earlier posting Stachowiak on Preterition and Abundance in Modelling here are some examples of Preterition and Abundance (also see here for all postings on Stachowiak):
Is this a black and white picture? Is this a colour image of a black/ white arrangement or a black/ white image of a coloured arrangement? In the latter case, even if you want not to express the colour of the Original at all, you have to choose some colour for the image (here, the scale from black to white).
Who triggers the Use Case? In UML the association between actor and use case is not allowed to have a direction. Thus, in order to express that an actor triggers the use case it are sometimes notated on the left hand side. So, the diagram could say that the customer triggers the use case or not. We cannot say, without any further information.
What does the graph tell about the maze? The graph inside the maze preserves coordinates and path length. Also in the graph on the right nodes have coordinates and edges have lengths. However, they are not meaningful anymore. They were ‘sacrificed’ for the sake of a certain view.*
Notice that a lot of further questions apply in the graph on the right: does the top element represent the starting point? Is 1-2-4-6-8 a kind of primary path (typical issue in process models)? Is it better to have all edges of equal length, to indicate the abundance?
So far, just a few examples that came to my mind.
*Stachowiak gives a similar example in his book “Allgemeine Modelltheorie”. The book at Google books.