When there is no free variable, there is no sum, just the loop. But you are right the the notion does not work as is because complicated subscript support is n

When there is no free variable, there is no sum, just the loop. But you are right the the notion does not work as is because complicated subscript support is not implemented yet. But the equation is listed before the programming part is mentioned and it is an illustration of idea, so I believe it is ok. It is not difficult to add the implementation, although it will be tedious (but still behind the surface). It is matter of how useful it is. And you are probably right that implementing a Levi-Civita syntax might be more straight forward.