Computer languages often use "set" to indicate only finite sets. Mathematics makes no such restrictions. The "transfiniteSet" defined here is a potentially infinite set usually internally defined by a Boolean function (here called 'contains') which returns TRUE if and only if the tested item is an element of the set. <br/><br/>This interface can be used on any set including finite enumerated sets, or potentially infinite sets defined by a test for 'contains.'<br/>