  Let G be a linear Lie group. We define the G-reducibility of a continuous or
discrete cocycle modulo N. We show that a G-valued continuous or discrete
cocycle which is GL(n,C)-reducible is in fact G-reducible modulo 2 if
G=GL(n,R),SL(n,R),Sp(n,R) or O(n) and modulo 1 if G=U(n).
