Fig. 9. Any one of the M+ extrema shown here is the tip of a protrusion, as predicted by our Semantic Interpretation Rule. What is important to observe is that, if one continued the process creating that protrusion, i.e. continued pushing out the boundary in the direction shown, the protrusion would remain a protrusion. That is, the M+ extremum would remain a M+ extremum. This means that continuation at a M+ extremum does not structurally alter the boundary. | back to text |