User blog comment:Ynought/Hyper extended array hierarchy/@comment-35470197-20190129040854/@comment-35470197-20190131134537

So you used not only the value of \(E_{k-1}\) but also the defining expression of \(E_{k-1}\) of the form \((x,\ldots,x)^{(x,\ldots,x)}_{(x,\ldots,x)} \leftarrow_{(a,b,\ldos,c)}\). Then I see.