then reconsider AmpS9 = AmpS9 as non emptyset ; set AmpS = { x where x is Element of AmpS9 : ex X being non emptySubset of R st ( X in M & AmpS9 /\ X ={x} ) } ; A6:
{ x where x is Element of AmpS9 : ex X being non emptySubset of R st ( X in M & AmpS9 /\ X ={x} ) } is non emptySubset of R