  A method developed by Polychronakos to study singular gauge transformations
in 1+2 dimensional non-commutative Chern-Simons gauge theory is generalized
from U(1) group to U(2) group. The method clarifies the singular behavior of
topologically non-trivial gauge transformations in non-commutative gauge
theory, which appears when the gauge transformations are viewed from the
commutative gauge theory equivalent to the commutative theory.
