Scaling-invariant reduction of the Tzitzeica equation
= Scaling-invariant reduction of the Tzitzeica equation
The <Tzitzeica equation> $u_{xy}=e^u-e^{-2u}$ is unchanged by $(x,y)\mapsto(cx,c^{-1}y)$. The identity component has generator $x\partial_x-y\partial_y$. Locally its invariant solutions are $u=w(xy)$, reducing the equation to $zw''+w'=e^w-e^{-2w}$.