On 02 Jun 2009, at 22:00, Brent Meeker wrote:
> > Bruno Marchal wrote: >> ... >> A set is entirely defined by its elements. Put in another way, we >> will >> say that two sets are equal if they have the same elements. >> Exercise 6. Let S be the set {0, 1, 45} and let M be the set >> described >> by {45, 0, 1}. Is it true or false that S is equal to M? >> Exercise 7. Let S be the set {666} and M be the set {6, 6, 6}. Is is >> true or false that S is equal to M? >> > > But there are no duplicates in sets; so {6,6,6} is either not a set > (instead it's a triple) or it's just strange notation for {6}. Right? Right. I was not well inspired with this exercise. At least it should have been given AFTER having said that a set is determined only by its elements. So {6, 6, 6} is really the same as the set {6}. Something like {6, 6, 6} is usually called a bag, and will never been used. Of course {666} is different from {6}. Apology. This will probably happen again, when I am distracted, so if an exercise seems weird or senseless, please don't panic! Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---