At the beginning we would like to introduce a refinement. The term 'VLSI planarization' means planarization of a circuit of VLSI, Le. the embedding of a VLSI circuit in the plane by different criteria such as the minimum number of connectors, the minimum total length of connectors, the minimum number of over-the-element routes, etc. A connector is designed to connect the broken sections of a net. It can be implemented in different ways depending on the technology. Connectors for a bipolar VLSI are implemented by diffused tun nels, for instance. By over-the-element route we shall mean a...