Degree growth of lattice equations defined on a 3 × 3 stencil
: Hietarinta, Jarmo
Publisher: Episciences
: 2024
Open Communications in Nonlinear Mathematical Physics
: Open Communications in Nonlinear Mathematical Physics
: 2024
: Special Issue 1
: 1
: 19
: 2802-9356
DOI: https://doi.org/10.46298/ocnmp.11589
: https://doi.org/10.46298/ocnmp.11589
: https://research.utu.fi/converis/portal/detail/Publication/484743359
We study complexity in terms of degree growth of one-component lattice equations defined on a 3 × 3 stencil. The equations include two in Hirota bilinear form and the Boussinesq equations of regular, modified and Schwarzian type. Initial values are given on a staircase or on a corner configuration and depend linearly or rationally on a special variable, for example fn,m = αn,m z + βn,m, in which case we count the degree in z of the iterates. Known integrable cases have linear growth if only one initial values contains z, and quadratic growth if all initial values contain z. Even a small deformation of an integrable equation changes the degree growth from polynomial to exponential, because the deformation will change factorization properties and thereby prevent cancellations.
Exactly Solvable and Integrable Systems, Nonlinear Sciences