The configuration space of abelian gauge theory on a periodic lattice becomes topologically disconnected when exceptional gauge field configurations are removed. It is possible to define a U(1)-bundle from the nonexceptional link variables by a smooth interpolation of the transition functions. The lattice analogue of the Chern character obtained using a cohomological technique based on noncommutative differential calculus is shown to give a topological charge related to the topological winding number of the U(1)-bundle.
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