A Discussion on the Different Notions of Symmetry of Differential Equations
arXiv:1012.1935
Abstract
A discussion is presented, within a simple unifying scheme, about different types of symmetry of PDE's, with the introduction and a precise characterization of the notions of "standard" and "weak" conditional symmetries, together with their relationship with exact and partial symmetries. An extensive use of "symmetry-adapted" variables will be made, and some clarifying examples are provided.
11 pages, no figures