Solution 14

 Following cases can be:

 1. You talk to the truthteller. He points at the lier. When you ask him (B= the lier), he points at the truthteller (A) .

 2. If A istead is the lier, he will point at the truthteller (B), who will point at the lier  (A).

 In both these cases A and B points at each other.

3. If you are talking to the one who sometimes lies sometimes tells the truth (A) and he at the moment is talking truth, he will point at the lier (B) who then will point at the truthteller (C) . If he (A) would choose to lie, he would point at the truthteller (B) som who in turn will point at the lier (C).

Whatever he chooses two other persons will be pointed at!

 CONCLUSION:

 If A and B points at each other (Cases 1. and 2.) they must be the truthteller and the lier. In that case is the one who sometimes lie, sometimes tells the truth.

 If they point at a third person, C (Case 3.),  A the one who sometimes lie, sometimes tells the truth. B and C must be the truthteller and the lier.

To separate the truthteller and the lier you can ask any of them: "Is one plus one equal to two?" 

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