----- Original Message ---- From: Fred lunnon <fred.lunnon@gmail.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Saturday, November 24, 2007 12:30:23 PM Subject: Re: [math-fun] The Axiom of Choice for roots of z^2 + 1 Which reminds me --- quite irrelevantly --- of a claim I fear I may have made previously in these august pages: that a most effective means of causing a polite gathering to descend into an incoherent brawl is to remark that "a mirror exchanges left with right" and then to enquire innocently "so, why doesn't it also exchange up with down?" A mirror neither exchanges left with right nor up with down. It exchanges front with back. This is precisely the definition of "reflection in a plane". Gene ____________________________________________________________________________________ Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now. http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ