Localized induction equation, Heisenberg chain, and nonlinear   Schrodinger equation
  The three equations named in the title are examples of infinite-dimensional completely integrable Hamiltonian systems, and are related to each other via simple geometric constructions. In this paper, these interrelationships are further explained in terms of the recursion operator for the Localized Induction Equation, and the recursion operator is seen to play a variety of roles in key geometric variational formulas. 
Joel Langer (Case Western Reserve University), Ron Perline (Drexel   University)