Discretionary channel routing using score function

For discretionary channel routing problems, some but not all the pins in the channel are required to be connected by their respective nets. It is solved in two phases: a selection phase, in which a set of pins that must be connected for each net is identified, and a connection phase, in which selected pins are interconnected to their respective nets. A new selection phase algorithm based on a simple score function is proposed. Its overall performance on examples taken from previous literature is better than that of four existing techniques.