System.out.printf("%s = %s%n", difference, evaluated);
assertEquals(evaluated, new LongRationalNumber(1, 2));
Expression product = new Multiplication(new LongRationalNumber(2, 3), new LongRationalNumber(9, 2));
ElementOf isNatural = new ElementOf(product, N);
evaluated = isNatural.evaluate();
System.out.printf("%s = %s : %s%n", product.evaluate(), isNatural, evaluated);
assertEquals(evaluated, TruthValue.True);
System.out.println(Q.create("-3.750"));
}