Abstract
We present a unified view of the transport properties of small polarons in the Holstein model at low carrier densities, based on the dynamical mean-field theory. The nonperturbative nature of the approach allows us to study the crossover from classical activated motion at high temperatures to coherent motion at low temperatures. Large quantitative discrepancies from the standard polaronic formulas are found. The scaling properties of the resistivity are analyzed, and a simple interpolation formula is proposed in the nonadiabatic regime.