How does one restrict the maximum length of elements in a context free grammar.... How would you structure rules to say only allow for elements of language to be of length seven and less.
With this you can even express it as a REGEX/FSA. All you need to do is essentially the same thing as you would in those machines, which is to make n amount of nodes which in your case 7. Basically it looks like this.
R -> <1><2>...<7>
<1> -> elements. | e
<2> -> elements. | e
..
<7> -> elements. | e