On Thu, Sep 12, 2013 at 01:21:28PM +0100, Neil Harris wrote: > On 12/09/13 11:26, Johan Winge wrote: > >On Wed, 11 Sep 2013 20:29:51 +0200, Hans Aberg > ><haber...@telia.com> wrote: > > > >>... The symbol for the empty set ∅ is originally a Greek letter > >>phi ϕ, ans some use the latter. > > > >According to the autobiography of André Weil, quoted at > >http://jeff560.tripod.com/set.html, the empty set symbol ∅ was > >inspired by the Scandinavian Ø, and would then have nothing to do > >with the Greek phi, except for a superficial resemblance. I'm > >aware that some mathematician indeed do use Φ/φ, supposedly due to > >this misconception and/or lacking coverage in fonts and/or > >carelessness, but I find it terribly annoying. Really, it is no > >more correct than using ß in lieu of β. > > > >-- Johan Winge > > > > > > Do some mathematicians _really_ use Φ/φ instead of ∅, or does it > just look like they're doing so?
Seems so: http://math.stackexchange.com/q/227548 Also, when I went to school we were taught that phi denotes a group of nothing, not sure if that was supposed to be the empty set (we were taught math in Arabic, so not sure how that translates into English). Regards, Khaled