User blog comment:King2218/Infinite Extensibility/@comment-5150073-20140314172340/@comment-1605058-20140315195358

I don't think it's really ill-defined. It's just that the way King is trying to define it relies too much on finite set of symbols he can use - namely arrows. Something like \(\uparrow[n]\) would work much better, because it is theoretically unlimited notation.