[1] Univ New Brunswick UNB, Fac Management, Fredericton, NB, Canada
[2] Beijing Univ Posts & Telecommun, Sch Sci, Beijing, Peoples R China
[3] Tech Univ Berlin, Inst Math, Fak II Math & Nat Wissensch, Kombinator Optimierung & Graphenalgorithmen COGA, Sekr MA 5-1, Berlin, Germany
[4] Tianjin Univ Technol, Inst Operat Res & Syst Engn, Coll Sci, Tianjin, Peoples R China