Institution: | 1. DEPARTMENT OF MATHEMATICS AND STATISTICS, THE OPEN UNIVERSITY, MILTON KEYNES, UNITED KINGDOMContract grant sponsor: EPSRC;2. contract grant number: EP/J006130/1;3. Contract grant sponsor: NSA;4. contract grant number: H98230‐12‐1‐0207;5. Contract grant sponsor: NSF;6. contract grant number: DMS‐1301692. The United States Government is authorized to reproduce and distribute reprints not‐withstanding any copyright notation herein.;7. MATHEMATICS DEPARTMENT, UNIVERSITY OF DERBY, DERBY, UNITED KINGDOM;8. DEPARTMENT OF MATHEMATICS, UNIVERSITY OF FLORIDA, GAINESVILLE, UNITED STATES OF AMERICA |