/**
* Axiom: |S| = n, then |P(S)| = 2ⁿ
* The cardinality (count) of a power set of S is 2ⁿ if the cardinality of S is n.
* @dataProvider dataProviderForSingleSet
*/
public function testCardinalityOfPowerSet(Set $A)
{
$P⟮S⟯ = $A->powerSet();
$n = count($A);
$this->assertEquals(pow(2, $n), count($P⟮S⟯));
$this->assertEquals(pow(2, $n), count($P⟮S⟯->asArray()));
}