Description of the illustration flip_node.eps

This figure illustrates a case of a node movement that would not be allowed, as explained in text before the illustration.

The topology consists of an isolated face F1 within face F2. Face F1 consists of nodes N1, N2, and N3 connected to form a triangle. Before the flip, node N1 is above the long edge of the triangle; and after the proposed but disallowed flip, node N1 would have been below the long edge.