:: deftheorem Def3 defines property(S) WAYBEL11:def 3 :
for T being non empty reflexive RelStr
for S being Subset of T holds
( S is property(S) iff for D being non empty directed Subset of T st sup D in S holds
ex y being Element of T st
( y in D & ( for x being Element of T st x in D & x >= y holds
x in S ) ) );