On shifting blocks and terminals to minimize channel density

We study in this paper the problem of minimizing channel density by simultaneously shifting the blocks that form the two sides of a channel and the terminals on the boundary of each block. Several special cases of this problem have been investigated, but no optimal algorithm was known for the general case. We present an optimal algorithm for solving this problem. For long channels, we also propose effective heuristic techniques to speed up our algorithm. Extensions as well as applications of our algorithms to detailed routing in building-block layout design are also discussed.<
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