The world-volume theory on a D-brane in a constant B-field background can be
described by either commutative or noncommutative Yang-Mills theories. These
two descriptions correspond to two different gauge fixing of the diffeomorphism
on the brane. Comparing the boundary states in the two gauges, we derive a map
between commutative and noncommutative gauge fields in a path integral form,
when the gauge group is U(1).Comment: 14 pages, harvmac; transformation of Wilson loop corrected, SW map at
the 2nd order correcte