public function testIntersectionAbsorbtion(Set $A, Set $B) { $A∩⟮B∪C⟯ = $A->intersect($A->union($B)); $this->assertEquals($A, $A∩⟮B∪C⟯); $this->assertEquals($A->asArray(), $A∩⟮B∪C⟯->asArray()); }