MathPHP\SetTheory\SetAxiomsTest::testADiffItselfIsEmptySet PHP Метод

    public function testADiffItselfIsEmptySet(Set $A)
    {
        $Ø = new Set();
        $A∖A = $A->difference($A);
        $this->assertEquals($Ø, $A∖A);
        $this->assertEquals($Ø->asArray(), $A∖A->asArray());
    }