/sci/ - Science & Math

>>11518692
>mfw I see people use \Sigma for summation
Also we perhaps don't want the [math]i[/math] index there since then [math]\sum_\alpha a_\alpha(x)D^\alpha[/math] ceases to be a linear operator on [math]f[/math], whence much of diff top/OA no longer apply. In particular I don't know how one would define the symbol of such an operator.