Ivo Bleylevens Ralf L. M. Peeters Bernard Hanzon Efficiency improvement in an nD systems approach to polynomial optimization. 30-53 2007 42 J. Symb. Comput. 1-2 http://dx.doi.org/10.1016/j.jsc.2006.03.008 db/journals/jsc/jsc42.html#BleylevensPH07