[1] Univ Catania, Dept Econ & Business, Corso Italia 55, I-95129 Catania, Italy
[2] Univ Portsmouth, Portsmouth Business Sch, Ctr Operat Res & Logist CORL, Richmond Bldg,Portland St, Portsmouth PO1 3DE, Hants, England
[3] Poznan Univ Tech, Inst Comp Sci, PL-60965 Poznan, Poland
[4] Polish Acad Sci, Syst Res Inst, PL-01447 Warsaw, Poland