Optional. Optimal allocation, maximum conditions, and Lagrange multipliers
- Let us consider the problem of an optimal economy, an economy that maximizes an objective function (profit or any other).
- Denoting Φ as the objective function to be maximized, X as the intensities of the processes, F as the matrix with the consumption and production flows, and D as the available quantities, the problem becomes
- X represents the unknowns; the rest are given data. We denote Y as the Lagrange multipliers corresponding to the balances for each material, D + X F ≥ 0 , the maximum conditions are
- We have that there are maximum conditions, where Lagrange multipliers are involved, one for each balance of each material, which must be satisfied for the allocation to maximize the objective.
- The term refers to the rates at which the target increases directly with the variation in the intensities of the processes.
- The Lagrange multipliers Y are the rates at which the objective increases with a variation in the constraints; they are the rates at which the objective would increase with the introduction of a small amount of the material; we will also call them the value of the material.
- The term F Y is the rate at which the target would indirectly increase with the consumption and production of materials by the processes.
- In order for the allocation to reach the greatest magnitude of the objective, while meeting the restrictions, it is necessary that what increases the objective directly plus indirectly is zero for the processes that operate, and not negative for those that do not operate.
- This is true in every isolated optimal economy, without exchanges, also in Robinson Crusoe's economy, where for Robinson things have value, and the processes that operate must be those in which they either contribute directly to Robinson's goal, or contribute indirectly through their consumption and production, or contribute in both ways.