We consider a new notion of circuit uniformity based on the concept of rational relations, called Rational-uniformity and denoted Rat. Our goal is to prove it is sharper than DLogTime-uniformity, the notion introduced by Barrington et al. [3], denoted DLT , that is: 1) Rational-uniformity implies DLogTime-uniformity, 2) we have NCRat NCDLT ( NCRat, 3) we have ∀k > 0, NCDLT ⊆ NC Rat , 4) Rationa...