### Error: no contradiction was found.

The logical formula had no property in negative position or Gappa has
discharged all of them, yet this was not sufficient to prove the formula.

{ x in [1,2] -> not x + 1 in [2,3] }

Error: no contradiction was found.

### Error: some enclosures were not satisfied.

Only part of a conjunction of goals was proved to be true. Gappa was
unable to prove some other expressions or formulas, which are displayed after
the message.

{ x in [1,2] -> x + 1 in ? /\ x + 2 in [2,3] }

Warning: case split on x + 2 has not produced any interesting new result.
Results:
x + 1 in [2, 3]
Error: some properties were not satisfied:
BND(x + 2), best: [3, 4]