Affiliation: | (1) Institute of Mathematics, Academia Sinica, Taipei, Taiwan & Department of Mathematics, University of Standard, USA (E-mail: tpliu@math.sinica.edu.tw; liu@math.stanford.edu),;(2) Department of Mathematics and Research Center of Applied Mathematics, C.I.R.A.M., University of Bologna, Italy (E-mail: ruggeri@ciram.unibo.it), IT |