

The graph of the function is the collection of points
in space determined by the planes

The dual graph of the function (Mapping figure) is the
collection of planes in space determined by the points

Problem: Suppose f (x,y) = z = 2x  3y... a linear function. 

The points on the graph all lie on a single plane in space.  Question: Do the planes of the dual graph determine
a single point in space?
Answer: ??? 