2. Intertemporal decision

In the models presented above, we have seen that the same good (for example, a given material such as wheat of a given quality) can be considered, from the model's point of view, as two different goods depending on whether it is delivered in Paris or Chicago, and therefore –– two different prices. Similarly, and in order to take into account the temporal dimension, this good (wheat of a given quality) can be seen as corresponding to two different goods depending on whether it is delivered immediately or in three months' time. Here too, these two goods will have different prices, known as – on the commodities market – spot and futures prices.

The time factor then becomes a characteristic like any other.

While this approach has the advantage of being synthetic, it ignores the dimensions specific to time, which mean that, in general, a good...