The Hamiltonian is then re-expressed as a function of degrees of freedom defined on a d-dimensional lattice.
Following Wilson, the spatial components of the vector potential are replaced with Wilson lines over the edges, but the time component is associated with the vertices.
However, the temporal gauge is often employed, setting the electric potential to zero.
The eigenvalues of the Wilson line operators U(e) (where e is the (oriented) edge in question) take on values on the Lie group G. It is assumed that G is compact, otherwise we run into many problems.
The conjugate operator to U(e) is the electric field E(e) whose eigenvalues take on values in the Lie algebra