User blog comment:Ynought/Extended array hierarchy/@comment-35470197-20190117222337

> you can even create stuff like this

But do you have any rule to compute \((\bullet)_{(\bullet_2)_{\bullet_3}}\)? Is it just \((\bullet)_{((\bullet_2)_{\bullet_3})}\), i.e. computed in a right associative way?

> a nests

What is a here? The leftmost entry of \(\bullet\) if \(\bullet\) is non-empty? If so, how to compute \((0,1)^0_{(0,1)}\)? You need to specify the order of rules to apply, because you have four rules applicable to it. (Deletion of the first 0, deletion of the second 0, deletion of the third zero, and the nesting rule.) I know that the deletion of the second 0 is not what you intend, but I do not know about the order of the other rules.