Integrable string models of hydrodynamical type
The closed string models are considered as the bi-Hamiltonian systems of hydrodynamical type. The local Poisson bracket (PB) of Dubrovin-Novikov, a general nonlocal (PB) of Ferapontov and nonlocal (PB) of Mokhov-Ferapontov for constant curvature surface were used to construct nonlinearb integrable string models of hydrodynamical type. The recursion operator was constructed. The second string Hamiltonian was obtained.