Affiliation: | 1. Department of Mathematics, Faculty of Mathematics and Physics, Charles University, Sokolovská 83, 186 75 Prague 8, Czech Republic;2. Institut de Mathématiques de Toulon, campus La Garde, 83041 Toulon, France;1. Universidade de São Paulo, Inst. de Ciências Matemáticas e de Computação, São Carlos, SP 13560-970, Brazil;2. Department of Mathematical Sciences, Faculty of Science, Yamagata University, Kojirakawa-machi 1-4-12, Yamagata 990-8560, Japan |