We consider a lattice gauge theory at finite temperature in (d+1)
dimensions with the Wilson action and different couplings βt and
βs for timelike and spacelike plaquettes. By using the character
expansion and Schwinger-Dyson type equations we construct, order by order in
βs, an effective action for the Polyakov loops which is exact to all
orders in βt. As an example we construct the first non-trivial order in
βs for the (3+1) dimensional SU(2) model and use this effective action
to extract the deconfinement temperature of the model.Comment: Talk presented at LATTICE96(finite temperature