On locally optimal breaking of nondisjoint cyclic vertical constraints in VLSI channel routing

Locally optimal breaking strategy was already developed for disjoint directed circuits in the vertical constraint graph. The paper reports extensions to two classes of nondisjoint circuits: with a common vertex, and with a common path. The significance of this is that the demonstration of general applicability of the locally optimal breaking concept opens a new approach to improving the channel router heuristics for automatic and interactive routers, using parallel architectures.