Sign debugging

debugging{ With $v_X\varphi =(X\cdot \partial +{\sigma }_X)\varphi$ and fixed numerical coefficients, one has $[v_X,v_Y]=-v_{[X,Y]}$. The representation statement is for ${\delta }_X=-v_X$, as in (eq:deltasign). Ignoring this distinction reverses a Lie-bracket sign.}