MathPHP\SetTheory\SetAxiomsTest::testCardinalityOfUnion PHP Method

    public function testCardinalityOfUnion(Set $A, Set $B)
    {
        $A∪B = $A->union($B);
        $A∩B = $A->intersect($B);
        $this->assertEquals(count($A) + count($B) - count($A∩B), count($A∪B));
        $this->assertEquals(count($A->asArray()) + count($B->asArray()) - count($A∩B->asArray()), count($A∪B->asArray()));
    }