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University of L'Aquila, Italy (UAQ)
Department of Information Engineering, Computer Science and Mathematics, via Vetoio (Coppito), 1 – 67100 L’Aquila (Italy)
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University of Hamburg , Germany (UHH)
Department of Mathematics
Bundesstr. 55
20146 Hamburg - Germany
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University of Côte d'Azur, Nice - France (UCA)
Laboratoire J.A.Dieudonné
Parc Valrose, France-06108 NICE Cedex 2