The symbolic computation of integrability structures for partial differential equations: Errata

Below is a list of known misprints in the book The symbolic computation of integrability structures for partial differential equations.

1. Page 57, the only displayed formula should be

   $L=\left({\frac {1}{3}}u(u_{xx}u_{tt}-u_{xt}^{2})-{\frac {1}{2}}(u_{x}u_{z}+u_{t}u_{y})\right)dx\wedge dz\wedge dt\wedge dy.$

   (change the minus sign before $u_{t}u_{y}$ into plus).

2. Page 195, equation (10.9), replace it with

   $\sum _{j}{\frac {\delta \Phi _{\mathcal {P}}}{\delta p^{j}}}p^{j}=-2\Phi _{\mathcal {P}}$

   (multiply the left-hand side by $p^{j}$ to the right).