CAS Problem

[parisse]

CAS == does not check if expressions are mathematically equivalent, it checks if they have the same internal representation (as expressions). Using == should therefore be limited to objects that are always in "normal" form like integers or rationals. For everything else, one should make the difference and apply some simplification rules, and see if it's 0 or not.
Note that for floats, using == should also not be used, instead one should take abs(difference) and compare to a (relative) precision.