Hamiltonian formulation for the gradient-power family

Construct a standard Hamiltonian formulation for the gradient-power dispersive equation when the gradient exponent satisfies $r\ne1$.

Background

The equation preserves mass and a nonlinear Lp+1L^{p+1} quantity, but the paper does not identify a Hamiltonian structure for general r≠1r\ne1. The authors distinguish this family from the Cooper–Shepard–Sodano compacton models, whose Hamiltonian or Lagrangian framework does not directly apply here.

A Hamiltonian formulation could provide variational methods and stability criteria that are currently unavailable for the evolution generator. The unresolved status is stated explicitly by the authors.

References

We do not know of a Hamiltonian formulation of eq:E for $r\neq1$, and the Lagrangian structure that underlies the $PT$-symmetric compactons of does not apply to the Rosenau--Hyman form of the nonlinear dispersion.

— Edge-cusped compactons from gradient-power nonlinear dispersion: exact transitions and singular spectral structure  (2610.00552 - Villatoro, 30 Sep 2026) in Section 2, paragraph discussing degeneracy for $r>1$; reiterated in Section 7