  We investigate the effect of electron-electron interactions on the
conductance of quasi one-dimensional systems without potential scattering. For
a finite temperature or system length, the short-range interaction is not
renormalized to 0, and it gives rise to a finite correction to the conductance
if we calculate it using Kubo formula. We show that this correction can be
absorbed into the renormalization of the chemical potential and that the
properly defined conductance to be observed in the experiments is equal to that
of non-interacting electrons.
