User blog comment:Mh314159/FOX notation updated/@comment-39585023-20191213105844/@comment-35470197-20191213110339

> Is it because of repeating n in "[n]‹n›(x) = is recursed using the same rule as f‹n›(x), treating [n] as f."

Right. Usually, the same symbol in a single formula has only a single meaning. So even if you intend that the n in [n] can differ from the n in , it is not allowed.

> I will change to "[u]‹n›(x) = is recursed using the same rule as f‹n›(x), treating [u] as f.".

It makes sense.

> I don't think I'm ever going to formalize my work to the extent that you would choose to, you being trained in formal math.

It is ok. I just gave a method to clearly formalise the recursion. Athough it might not be helpful for you now, it might be helpful in the future.