... the FD A -+ B.LetFTbe a family of all FDs that hold in r. ThenF=FTsatisfies(1) A -+ AEF,(2) (A -+ B E F, B -+ CE F)=>(A -+ CE F),(3) (A -+ BEF, A ~C,D ~ B)=>(C -+ DEF),(4)(A -+ B ... B)=>(C -+ DEF),(4)(A -+ B E F,C -+ D E F)=>(AuC -+ BuD E F).A family of FDs satisfying(1) - (4)is called an I-family (sometimes it is called the full family]over R.Clearly,FTis an I-family ... ifLis a meet-irreducible family thenLis the minimal generator of someclosure operation overR.It is known [1] that there is an one-to-one correspondence between thesefamilies and f-families.Letrbe...