As was true of the social optimum, the λ = 0 locus can be either upward or downward sloping. If D_1f(k, Sk)> δ for all k greater than some value ḱ, the λ = 0 locus will lie above ḱ = 0 for values of k to the right of ḱ. Then the qualitative analysis is the same as that presented for the social optimum. Starting from an initial value k_0 > ḱ, the only candidate paths for equilibria are ones that stay above the ḱ = 0 region; as before, paths that cross into this region will violate the transversality condition. A trajectory lying everywhere in the region where ḱ > 0 can fail to have k(t) grow without bound only if the trajectory asymptotically approaches a critical point where λ and ḱ are both zero, but no such point exists to the right of ḱ. Hence, all the trajectories that are possible candidates for an equilibrium have paths for k(t) that grow without bound. The existence result in theorem 2 shows that at least one such path satisfies the transversality condition at infinity.