Affiliation: | a DIMAP and Mathematics Institute, University of Warwick, Coventry, CV4 7AL, UKb Department of Applied Mathematics and Informatics, Higher School of Economics (Nizhny Novgorod branch), Bolshaya Pecherskaya str. 25/12, 603155, Nizhny Novgorod, Russiac Department of Mathematical Logic and Higher Algebra, University of Nizhny Novgorod, Gagarina av. 23, 603950, Nizhny Novgorod, Russiad DIMAP and Department of Computer Science, University of Warwick, Coventry, CV4 7AL, UK |