A12:
for A being set st A in g holds ( A <>{} & ( for B being set holds ( not B in g or A = B or A misses B ) ) )
byEQREL_1:def 4; A13:
for A being Subset of Y st A in X holds ( A <>{} & ( for B being Subset of Y holds ( not B in X or A = B or A misses B ) ) )