This is also a great example of the difference between '=' and '=='. If the statement a = b, where to precede everything, then Sage would know that a - b = 0, and would convert the statement 'a==b' to 'b==b', which would frustrate the proof.
Jonathan On May 23, 1:44 am, David Kirkby <david.kir...@onetel.net> wrote: > On 21 May 2011 10:35, Juanlu001 <juanlu...@gmail.com> wrote: > > > Yesterday I was playing with symbolic expressions, and I had to apply > > divide_both_sides(), and I encountered something funny: you can divide > > by zero (with a bit of care). To show this, I've taken the classic > > "proof" and created a worksheet: > > >http://flask.sagenb.org/home/pub/65/ > > > Though I have got useful notices using other functions (such as "Is x > > greater than zero?" when trying to solve an equation), I think that an > > assumption should be made about the expression we are dividing by to > > finally make the division. > > > Ideas? > > This reminds me of my school days. One of the guys in our chemistry > class came up with a mathematical proof that proved humans did not > exist. So we totally ignored him for the rest of the day! The > cheamistry teacher asked why we was ignoring David B, so we told him > that since David B had proved we did not exist, how would we be > ignoring him. > > Dave -- 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
