Bravo Thunderbird!

On 07 Jun 2009, at 18:39, m.a. wrote: > >> Bruno et. al., >> Good news! I have discovered that the math >> symbols copy faithfully here in my Thunderbird email. Henceforth, I >> will open all list letters here. Please refresh my memory for the >> following symbols: >> >> >> 1. The ∅ is called___THE EMPTY SET_____and means______THE SET >> WITH NO ELEMENTS The empty set described in extension: { } The empty set described in intension. Well, let me think. The set of french which are bigger than 42 km tall. A cynical definition would be: the set of honest politicians. A mathematical one: the set of x such that x is different from x. It is just the set which has no elements. It is empty. >> >> 2. The ∪ is called________UNION______and means: A ∪ B__= {x >> such-that x belongs to A or x belongs to B}; >> A u B is the set obtained by doing the union of A and B. >> 3. The ∩ is called_____INTERSECTION____and means__A ∩ B__= >> {x such-that x belongs to A andr x belongs to B}; A u B is the >> set obtained by doing the intersection of A and B. It is the set of >> elements which are in both A and B._ Examples: {1, 2, 3} ∩ {2, 4, 3} = {2, 3} {1, 2, 3} u {2, 4, 3} = {1, 2, 3, 4} {1, 2, 3} ∩ {4, 5, 6} = ∅ {1, 2, 3} u {4, 5, 6} = {1, 2, 3, 4, 5, 6} OK? Bruno >> >> >> ----- Original Message ----- >> From: Bruno Marchal >> To: everything-list@googlegroups.com >> Sent: Wednesday, June 03, 2009 1:15 PM >> Subject: Re: The seven step-Mathematical preliminaries 2 >> >> >> ∅ ∪ A = >> ∅ ∪ B = >> A ∪ ∅ = >> B ∪ ∅ = >> N ∩ ∅ = >> B ∩ ∅ = >> ∅ ∩ B = >> ∅ ∩ ∅ = >> ∅ ∪ ∅ = >> >> >> >> > > > 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 -~----------~----~----~----~------~----~------~--~---