Swelled Set which is Closed under Chain Unions with Choice Function is Type M/Historical Note

Historical Note on Swelled Set which is Closed under Chain Unions with Choice Function is Type $M$
and, in their of $2010$, demonstrate only the sufficient condition: that a swelled set with the given criteria is of type $M$.

In raising the question as to whether such a set of sets which is not swelled would also be of type $M$, they say:


 * We posed this question to Professor, who informed us that it would not.