theorem Th22: :: COHSP_1:22

for f being Function st dom f is subset-closed & dom f is d.union-closed holds
( f is U-stable iff ( f is c=-monotone & ( for a, y being set st a in dom f & y in f . a holds
ex b being set st
( b is finite & b c= a & y in f . b & ( for c being set st c c= a & y in f . c holds
b c= c ) ) ) ) )