The intersection of these two curves at point A describes the steady state long-run equilibrium. All trajectories that do not converge to this point violate (违反) an equilibrium requirement over some time interval (see Grossman and Helpman [1991b]). The equilibrium trajectory consists of the saddle (鞍点) path that converges to A. Along this saddle path the rate of innovation declines over time and the faction of products that have not been imitated increases over time whenever the latter falls short of its steady state value, and the rate of innovation increases over time and the fraction of products that have not been imitated declines over time whenever the latter exceeds its steady state value.