Geometric aspects of non-homogeneous 1+0 operators
Abstract
Led by the key example of the Korteweg-de Vries equation, we study pairs of Hamiltonian operators which are non-homogeneous and are given by the sum of a first-order operator and an ultralocal structure. We present a complete classification of the Casimir functions associated with the degenerate operators in two and three components. We define tensorial criteria to establish the compatibility of two non-homogeneous operators and show a classification of pairs for systems in two components, with some preliminary results for three components as well. Lastly, we study pairs composed of non-degenerate operators only, introducing the definition of bi-pencils. First results show that the considered operators can be related to Nijenhuis geometry, proving a compatibility result in this direction in the framework of Lie algebras.
Cite
@article{arxiv.2503.21917,
title = {Geometric aspects of non-homogeneous 1+0 operators},
author = {Marta Dell'Atti and Alessandra Rizzo and Pierandrea Vergallo},
journal= {arXiv preprint arXiv:2503.21917},
year = {2026}
}
Comments
44 pages, 1 figure