Talk:Axiom of Choice implies Zorn's Lemma/Proof 2

Meaning of square brackets
What is the meaning of the square brackets in

Is it something to do with ordinals? Is it the application of a function to a set (i.e. $f[X] := \{f(x) \, | \, x \in X\}$)? Whatever it is, it should be explained in the proof.


 * I've taken a look. Not one of my pages this one, so I'm not sure myself. But there is a fair amount of specialised notation in the exposition of ordinals (which was going to be reviewed and rationalised at one point, never got round to it) where it may be explained. I've added a maintenance tag to it with a view to revisiting it. I've also taken the opportunity of tidying up the source code while I was about it. --prime mover (talk) 12:07, 19 April 2019 (EDT)