On Fri, 6 Aug 2010 07:06:33 +1000, Peter Jeremy <peterjer...@acm.org> wrote: > On 2010-Aug-04 14:51:21 -0700, Nils Bruin <nbr...@sfu.ca> wrote: > >There are other areas of mathematics where "<" gets used for proper > >inclusion. A group theorist is going to be very surprised if for two > >groups H,G, the expression "H < G" is valid but does not mean "H is a > >subgroup of G". > > I expect this is primarily due to the restrictions of the ASCII > character set. More appropriate set comparison and manipulation > characters were defined about 50 years ago in APL: ∩ ∪ ⊂ ⊃ ⊆ ⊇ > (For those without appropriate glyphs available, these are Unicode > codepoints U+2289, U+228A, U+2282, U+2283, U+2286 and U+2287)
While this is true, I believe Nils' point was that mathematicians often use H < G to say that H is a subgroup of G, even when they write such things by hand, where they're not bound by the ASCII character set (or even Unicode). Best, Alex -- Alex Ghitza -- http://aghitza.org/ Lecturer in Mathematics -- The University of Melbourne -- Australia -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
