Institution: | 1. Instituto de Matemáticas, UNAM Juriquilla, Querétaro 76230, Mexico;2. Université de Lyon, CNRS, Université Lyon 1, LIRIS, UMR 5205, Lyon, 69622, France;3. Institut of Mathematics, University of Zielona Góra ul. prof. Z. Szafrana 4a, 65–516 Zielona Góra, Poland |