[1
]Department of MathematicsImperial College LondonLondon SW7 2AZ United Kingdom
[2
]Department of Applied Mathematics (KAM)Charles UniversityMalostranské nám. 25 11800
Praha Czech Republic
[3
]Computer Science Institute of Charles University (IUUK)Charles UniversityMalostranské
nám. 25 11800 Praha Czech Republic