Commutator identity for Lie derivatives (source code)

= Commutator identity for Lie derivatives
{title2=$[\mathcal L_X,\mathcal L_Y]=\mathcal L_{[X,Y]}$}

The <Lie derivative of a tensor field> satisfies $[\mathcal L_X,\mathcal L_Y]=\mathcal L_{[X,Y]}$. On <smooth functions> this is the definition of the <Lie bracket of vector fields>; on <vector fields> it follows from the <Jacobi identity>. The <Leibniz rule> and contraction compatibility extend the equality to <tensor fields>. The cyclic double-commutator identity also follows directly from associativity of operator composition.