Note and Comments: On Putty-Clay: A Comment

International Trade Theory in Vintage Models

“…We need to consider how k varies along the" wage frontier". Although Britto [5] has shown that if the elasticity of substitution of the function f(k) is less than 1, k is uniquely determined by r in Bliss's model, no corresponding result appears to hold in this model. I am forced to make the assumption…”

“…... (4) ... (5) The fact that there are wage and profit rate differentials reflects an assumption that there are no international flows of labour or investment. The immobility of investment does not irrrply that machines are internationally immobile, only that a machine being used 'in one country may not be owned in another country, and the absence of any other price differentials indicates free trade in machines and in the output good.…”

Technical progress, factor substitutability and models of production: II

“…4 Thus, when OQvt/OZvt exhibits a finite maximum, capital can be scrapped while physically alive. 5 The simultaneous scrapping of all vintages is, however, a trivial solution.…”