{ "id": "1506.02309", "version": "v1", "published": "2015-06-07T20:07:46.000Z", "updated": "2015-06-07T20:07:46.000Z", "title": "Deformations of non semisimple Poisson pencils of hydrodynamic type", "authors": [ "Alberto Della Vedova", "Paolo Lorenzoni", "Andrea Savoldi" ], "comment": "45 pages", "categories": [ "math-ph", "math.MP", "nlin.SI" ], "abstract": "We study deformations of two-component non semisimple Poisson pencils of hydrodynamic type associated with Balinski\\v{\\i}-Novikov algebras. We show that in most cases the second order deformations are parametrized by two functions of a single variable. It turns out that one function is invariant with respect to the subgroup of Miura transformations preserving the dispersionless limit and another function is related to a one-parameter family of truncated structures. In two expectional cases the second order deformations are parametrized by four functions. Among them two are invariants and two are related to a two-parameter family of truncated structures. We also study the lift of deformations of n-component semisimple structures. This example suggests that deformations of non semisimple pencils corresponding to the lifted invariant parameters are unobstructed.", "revisions": [ { "version": "v1", "updated": "2015-06-07T20:07:46.000Z" } ], "analyses": { "keywords": [ "hydrodynamic type", "second order deformations", "two-component non semisimple poisson pencils", "non semisimple pencils", "n-component semisimple structures" ], "note": { "typesetting": "TeX", "pages": 45, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2015arXiv150602309D" } } }