[1] Ritsumeikan Univ, Dept Math Sci, 1-1-1 Nojihigashi, Kusatsu, Shiga 5258577, Japan
[2] Japan Sci & Technol Agcy, 1-1-1 Nojihigashi, Kusatsu, Shiga 5258577, Japan
[3] Univ Lorraine, IECL, UMR 7502, F-54500 Vandoeuvre Les Nancy, France
[4] CNRS, IECL, UMR 7502, F-54500 Vandoeuvre Les Nancy, France
[5] INRIA, F-54500 Villers Les Nancy, France