solveset returns ConditionSet

[maurogaravello]

solveset returns ConditionSet in case it is not able to find the solution.
As an example, look at the code

x = Symbol('x', real=True)
f = atan(log(x))
domain = Interval.open(0, oo)
sign = solveset(f>0, x, domain=domain)

In this case, sign is ConditionSet(x, atan(log(x)) > 0, Interval(0, oo)).
It is also simple to see that the solution is Interval.open(1, oo).