Comment #1 on issue 3546 by asmeu...@gmail.com: 0*x http://code.google.com/p/sympy/issues/detail?id=3546
I think this was discussed before. If 0*x remained unevaluated, then nothing would work like you want it to. x - x would not go to 0. Try making the change in the core and seeing how many tests fail.
-- You received this message because you are subscribed to the Google Groups "sympy-issues" group. To post to this group, send email to sympy-issues@googlegroups.com. To unsubscribe from this group, send email to sympy-issues+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy-issues?hl=en.