SIGMA 7 (2011), 081, 8 pages
arXiv:1104.4034 http://dx.doi.org/10.3842/SIGMA.2011.081
Daryoush Talati and Refik TurhanDepartment of Engineering Physics, Ankara University 06100 Tandogan Ankara, Turkey
Received April 25, 2011, in final form August 18, 2011
Published online August 20, 2011
We show that a recently introduced fifth-order bi-Hamiltonian equation with a differentially constrained arbitrary function by A. de Sole, V.G. Kac and M. Wakimoto is not a new one but a higher symmetry of a third-order equation. We give an exhaustive list of cases of the arbitrary function in this equation, in each of which the associated equation is inequivalent to the equations in the remaining cases. The equations in each of the cases are linked to equations known in the literature by invertible transformations. It is shown that the new Hamiltonian operator of order seven, using which the introduced equation is obtained, is trivially related to a known pair of fifth-order and third-order compatible Hamiltonian operators. Using the so-called trivial compositions of lower-order Hamiltonian operators, we give nonlocal generalizations of some higher-order Hamiltonian operators.
Key words: bi-Hamiltonian structure; Hamiltonian operators.
+ داریوش طلعتی