April Rasala Lehman Gordon T. Wilfong http: //epubs.siam.org/SICOMP/volume-35/art_43425.html. 449-485 2005 35 SIAM J. Comput. 2 http://epubs.siam.org/SICOMP/volume-35/art_43425.html db/journals/siamcomp/siamcomp35.html#LehmanW05