where -λ equals the negative characteristic root (i.e., λ>0) and [1-Λ]^Trepresents the characteristic vector associated with the negative characteristic root, with Λ>0. This solution describes the same directions in the evolution of ζ and g as does Figure 1. From these equations we now calculate the response of (ζ,g) to a tightening of intellectual property rights. Taking into account the initial condition ζ(0)=ζ ̅, we obtain。