title: Universal geometric condition for the transverse instability of solitary waves
abstract: Transverse instabilities correspond to a class of perturbations traveling in a direction transverse to the direction of the basic solitary wave. Solitary waves traveling in one space direction generally come in one-parameter families. We embed them in a two-parameter family and deduce a new geometric condition for transverse instability of solitary waves. This condition is universal in the sense that it does not require explicit properties of the solitary wave-or the governing equation. In this paper the basic idea is presented and applied to the Zakharov-Kuznetsov equation for illustration. An indication of how the theory applies to a large class of equations in physics and oceanography is also discussed.
authors.affiliation: Department of Mathematics and Statistics, University of Surrey, Guildford, Surrey GU2 5XH, United Kingdom.
authors.initials: TJ
authors.lastname: Bridges