Group analysis of the one-dimensional Boltzmann equation

Abstract

The one-dimensional Boltzmann equation $f_{t} + cf_{x} + (\mathcal {F} f)_{c} = 0$ is considered with the function $\mathcal{F}$ depending on $(t, x, c, f)$. In this paper we obtain a complete group classification of such equations in the class of point transformations of the entire set of variables $(t, x, c, f)$ under the conditions of invariance of a) the relations $dx = cdt$, $dc = \mathcal {F} dt$, b) the lines $ dt = dx = 0 $ and c) the form $fdxdc$ fixing the physical meaning of the variables and the relationships between them.