Stability of Flows of Ideal Fluids and the Geometry of the Group of Diffeomorphisms Gerard Misiolek Indiana University Mathematics Journal 1993 text pdf 10.1512/iumj.1993.42.42011 10.1512/iumj.1993.42.42011 en Indiana Univ. Math. J. 42 (1993) 215 - 235 state-of-the-art mathematics http://iumj.org/access/