  Using the method of decisive creatures (math.LO/0601083) we show the
consistency of "there is no increasing omega_2 --chain of Borel sets and
non(N)=non(M)= omega_2=2^omega". Hence, consistently, there are no monotone
hulls for the ideal M cap N . This answers Balcerzak and Filipczak. Next we use
FS iteration with partial memory to show that there may be monotone Borel hulls
for the ideals M, N even if they are not generated by towers.
