Hiroshige Fujii Goichi Ootomo Chikahiro Hori Interleaving based variable ordering methods for ordered binary decision diagrams. 38-41 1993 conf/iccad/1993 ICCAD http://doi.acm.org/10.1145/259794.259801 db/conf/iccad/iccad1993.html#FujiiOH93