org.junit.Assert.assertEquals(new Interval(-5, Double.POSITIVE_INFINITY),
sem.minus(new Interval(Double.NEGATIVE_INFINITY, 5)));
org.junit.Assert.assertEquals(new Interval(3, Double.POSITIVE_INFINITY),
sem.minus(new Interval(Double.NEGATIVE_INFINITY, -3)));
org.junit.Assert.assertEquals(new Interval(0, 0), sem.minus(new Interval(0, 0)));
org.junit.Assert.assertEquals(new Interval(-2, 0), sem.minus(new Interval(0, 2)));
org.junit.Assert.assertEquals(new Interval(0, 2), sem.minus(new Interval(-2, 0)));
org.junit.Assert.assertEquals(new Interval(1, 2), sem.minus(new Interval(-2, -1)));
org.junit.Assert.assertEquals(new Interval(-2, -1), sem.minus(new Interval(1, 2)));
org.junit.Assert.assertEquals(new Interval(-5, 3), sem.minus(new Interval(-3, 5)));