In this note, we study the Yang–Mills bar connection
A , i.e., the curvature of
A obeys
\bar\partial_A^\astF_A^0,2 = 0 , on a principal
G -bundle
P over a compact complex manifold
X . According to the Koszul–Malgrange criterion, any holomorphic structure on
P can be seen as a solution to this equation. Suppose that
G = SU(2) or
SO(3) and
X is a complex surface with
H^1(X,\mathbbZ_2) = 0 . We then prove that the
(0,2) -part curvature of an irreducible Yang–Mills bar connection vanishes, i.e.,
(P,\bar\partial_A) is holomorphic.