  The complete integrability of the Ostrovsky-Vakhnenko equation is studied by
means of symplectic gradient-holonomic and differential-algebraic tools. A
compatible pair of polynomial Poissonian structures, Lax type representation
and related infinite hierarchies of conservation laws are constructed. A new
bi-infinite hierarchy of completely Lax type integrable Riemann type
hydrodynamical systems is proposed. It is demonstrated that at s=3 the
corresponding Riemann type hydrodynamical equation is related with the
Degasperis-Processi equation, whose reduction gives rise to the
Ostrovsky-Vakhnenko equation.
