solver.post(ICF.arithm(vars[n - 2], "!=", vars[n - 1]));
solver.set(ISF.lexico_LB(vars));
solver.set(new RecorderExplanationEngine(solver));
ConflictBasedBackjumping cbj = new ConflictBasedBackjumping(solver.getExplainer());
cbj.activeUserExplanation(true);
// SMF.shortlog(solver);
Assert.assertFalse(solver.findSolution());
Explanation exp = cbj.getUserExplanation();
Assert.assertEquals(2, exp.nbPropagators());
}