1. Institut Polytechnique de Bordeaux INRIA Bordeaux Sud Ouest, Team: CQFD, IMB Institut de Mathématiques de Bordeaux, Université de Bordeaux, Talence, France
2. Department of Mathematical Sciences, University of Liverpool, Liverpool, UK
3. Center for R&D in Mathematics and Applications, Department of Mathematics, University of Aveiro, Aveiro, Portugal
4. Institute for Information Transmission Problems, Moscow, Russia