Kvant
Miscellany

What does indecisiveness lead to?

Rough automatic draft, low quality: expect mistakes and awkward wording. It will be replaced by a better translation. Original →

variables, and the corresponding definitions are transferred by analogy to the general case.

On the other hand, the value of a geometric language lies in the fact that intuition can suggest some constructions and methods for solving problems that are difficult to figure out if you use only algebraic language. The Simpleskmethod provides a good example of such a technique. Because of this, it turns out to be useful to introduce geometric language in the case of an arbitrary number of variables.

Exercises

  1. Prove that if the planes
    x1+x2+x3=Kx_1 + x_2 + x_3 = K
    are parallel to some face of the polyhedron AA, then the plane
    x1+x2+x3=K0x_1 + x_2 + x_3 = K_0
    coincides with the plane of this face.

  2. Is it true that if the planes
    x1+x2+x3=Kx_1 + x_2 + x_3 = K
    are parallel to some edge of the polyhedron AA, then the plane
    x1+x2+x3=K0x_1 + x_2 + x_3 = K_0
    goes through this rib?

  3. a) Let the problem of choosing technological resources set the task of maximizing not the output, but the approximation, that is, the difference between the price of the produced product and the cost of using the resource in production, and it is known that the price of a unit of produced product is equal to qq rubles, the cost of using units of the jj resource is equal to qjq_j rubles (j=1,…,mj=1,\dots,m).

  1. Let the choice problem be technological, so that the output is no less than SS units and at the same time that the costs are minimal.

Formulate each of these problems as a linear programming problem. Prove that there is exactly one value SS for which the solutions to problem 6) coincide with the solutions to problem a).

Literature

A. S. Solodovnikov, Introduction to linear algebra and linear programming. M., “Enlightenment”, 1966.