sympy/sympy — pull request #1141 by rlamy (2012-03-19 05:28:17+00:00)
Title: Move is_comparable out of the assumption system

`is_comparable` doesn't fit with the rest of the assumptions, it doesn't make sense to assume that a Symbol is comparable. So it's more consistent to make it an ordinary property, like `is_number`

This also removes the hardcoded fallback to evalf() to evaluate assumptions `is_positive`, `is_negative`, etc. This behavior is now implemented in Expr._eval_is_positive and Expr._eval_is_negative instead.