Talk:Countable Union of Countable Sets is Countable/Informal Proof

Unless I'm missing something, Countable Union of Countable Sets is Countable/Proof 1 is basically, if not exactly, a formalized version of this argument. That's the reason that I replaced this argument with that one. Comments? --abcxyz (talk) 17:00, 14 December 2012 (UTC)