User blog comment:VoidSansXD/Ordinal notation/@comment-35434595-20190217190037/@comment-30869823-20190222202637

You can't just define something as "the n-th symbol", we all know what you mean, but you have to rigorusly define it allong with a fundamental sequance, such that we know precisely who we could compute \( f_{\Delta n} \), this is typically done by defininig what the first symbol is and how you get the next symbol out of the previous one.

Also Δ(Δ1) = Δw is meaningless because you haven,'t definied what Δw is.