[1] Univ Milan, Dept Econ Management & Quantitat Methods, I-20122 Milan, Italy
[2] Khalifa Univ, Dept Appl Math & Sci, Abu Dhabi, U Arab Emirates
[3] Univ Wollongong, Sch Accounting Econ & Finance, Wollongong, NSW 2522, Australia
[4] Acadia Univ, Dept Math & Stat, Wolfville, NS B0P 1X0, Canada
[5] Univ Turin, Dept Econ & Stat Cognetti de Martiis, I-10153 Turin, Italy