@ -253,8 +253,8 @@ remember to replace (auto-tra) with your initials (YYY).
[FR] transformation de Galilée
[EN] Galileo's transformations
$`\mathbf{\begin{matrix}
\left \{
$`\mathbf{
\left\{\begin{matrix}
t'=t \\
x'=x-V_x\,t \\
y'=y-V_y\,t \\