http://math.stackexchange.com/questions/24119/difference-between-pairwise-distinct-and-unique http://math.stackexchange.com/questions/24119/difference-bet... I

http://math.stackexchange.com/questions/24119/difference-between-pairwise-distinct-and-unique http://math.stackexchange.com/questions/24119/difference-bet... It seems the article's use of unique does not matter much in the context. The level of math explanation seems an over-kill.