Walter Montego:Aint's is accepted here.  But it is said to be a rather informal form of am not, etc,. so It's better to avoid using it when speaking formally, which is often the case here in universities.

I've heard of no exceptions to what I said regarding 'have.'  If it means 'to possess,' it shouldn't be contracted.  Otherwise it can be.  That's all I've been taught.  But the natives make up the rules.  Except that 'notion' example, do you have any other cases in mind in which 'have' means 'to possess' but it is contracted?