you may well be right in which case i don't agree with the present framing of wp or as it's being applied to mathematics articles i don't consider it any more original research to invent an example like than it is to invent a graphic showing the basic structure of a virus in any case i've seen the example of the cooks and their measuring jugs elsewhere and it not infrequently appears in one form or another in iq type tests so it's not an invented example anyway but my fundamental position is that anyone who has followed the exposition of the algorithm to that point would have no difficulty in perceiving the truth of the statement so a citation would only be there to reassure those who haven't understood what's been said that's surely not the purpose of providing citations fatuorum