We empirically assess the implications of fixed terminals for hypergraph partitioning heuristics. Our experimental testbed incorporates a leading-edge multilevel hypergraph partitioner [14] [3] and IBM-internal circuits that have recently been released as part of the ISPD-98 Benchmark Suite [2, 1]. We find that the presence of fixed terminals can make a partitioning instance considerably easier (possibly to the point of being "trivial"): much less effort is needed to stably reach solution qualities that are near bestachievable. Toward development of partitioning heuristics specific to the fixed-terminals regime, we study the pass statistics of flat FM-based partitioning heuristics. Our data suggest that with more fixed terminals, the improvements in a pass are more likely to occur near the beginning of the pass. Restricting the length of passes ? which degrades solution quality in the classic (free-hypergraph) context ? is relatively safe for the fixed-terminals regime and c...
Andrew E. Caldwell, Andrew B. Kahng, Igor L. Marko