1. Introduction
This article is the first in formulating the principles of sustainable economic development. In this formulation, the question of the existence of economic equilibrium under fairly general assumptions regarding the structure of supply and the structure of demand plays a significant role. The economic reality generates the problems the solution of that is only possible by a new paradigm of the description of economy system. The classical mathematical economics is based on a notion of the rational consumer choice generated by a certain preference relation on some set of goods a consumer wanted and the concept of maximization of the firm profit. The sense of the notion of the rational consumer choice is that it is determined by a certain utility function, defining the choice of a consumer by maximization of it on a certain budget set of goods. Moreover, choices of consumers are independent. In the reality choices of consumers are not independent because they depend on the firms supply.
Except the firms supply, the consumer choice is also determined by information about the state of the economy system that the consumer has and respectively evaluates at the moment of the choice. In turn, the firms supply is made on the basis of needs of the consumers and their buying power. By information about the state of the economy system we understand a certain information about the equilibrium price vector and productive processes realized in the economy system under the equilibrium price vector.
The new concept of the description of the economy system is to construct the stochastic model of the economy system based on the principle that the firms supply is primary and the consumers choice is secondary. Consumers make their choice by having information about the state of the economy system that is taken into account by them under the choice. Firms make decisions relative to productive processes on the basis of information about the real needs of consumers and this principle is called the agreement of the supply structure with the choice structure.
To construct such a theory, it is necessary to formulate adequate to the reality the theory of consumers choice and decisions making by firms. Thus, the main foundations of the stochastic model of economy system are the notions of consumers choice and decisions making by firms relative to productive processes. Under uncertainty these two notions have the stochastic nature. Besides, the theory of consumers choice must take into account the structure of supply and mutual dependence of the consumers choice.
So, the sense of the new paradigm of the description of the economic phenomena is to construct models of the economy systems, describing adequately consumers choice and decisions making by firms relative to productive processes, that give possibility to use them for finding the conditions of the stable growth of real economy systems (see [1] ).
This work is the implementation of the ideas laid down in [1] for the formulation of the concept of sustainable economic development at the microeconomic level. In the next paper, we clarify the issue of the influence of spontaneous output of goods by firms on the phenomenon of recession, formulate the concept of sustainable economic development.
The Section 2 is devoted to the investigation of technological maps that describe production of firms. The most important among them are technological maps from the CTM class (compact technological maps) and from the CTM class in a wide sense. The notion of optimal strategy of firm behavior is introduced and the proposition 1 of the existence of optimal strategy of firm behavior for technological maps from the CTM class in a wide sense is proved. A technological map given by the formula (3) is introduced, the Lemma 3 on the belonging of this technological map to the CTM class in a wide sense and its convexity down is proved. In the Lemma 4 an algorithm of the construction of optimal strategy of firm behaviour for the technological map given by the formula (3) is presented. The Lemma 6 is fundamental for further investigation and proves for the technological map, given by the formula (3), the existence of continuous strategy of firm behavior that is arbitrary close in income to the optimal one. By a convex down technological map from the CTM class in a wide sense, a technological map given by the formula (4) is constructed and the Lemma 7 about the belonging of the constructed technological map to the CTM class and its convexity down is proved. In the Lemma 8 the structure of optimal strategy of firm behavior for a technological map given by the formula (4) is found. The Lemma 9 guarantee the convergence of the sequence of optimal incomes for technological maps of the type (4) to optimal income of the technological map by that the sequence of technological maps is constructed. The basic result is the Theorem 1, in which under wide assumptions the existence of continuous strategy of firm behavior that is arbitrarily close in income to optimal strategy of firm behavior is proved.
Section 3 contains Theorems of the existence of economic equilibrium in the case of the general form of consumer demand and firm supply. In Theorem 2, the existence of a solution to the system of Equation (9) is established under fairly general assumptions about the structure of technological mappings, consumers income functions, and the production economic process. Using this result and auxiliary Theorem 3, Theorem 4 establishes the existence of an economic equilibrium. The disadvantage of Theorem 4 is the fact that each economic agent must own all types of goods in order to fulfill the condition of having a strictly positive income for each economic agent.
In this work, which continues and develops the works of [2] - [6] for the case of the economy under conditions of uncertainty, new mathematical methods of proving theorems of the existence of economic equilibrium and constructive methods of constructing equilibrium states have been developed. In the works [2] , [3] the existence of economic equilibrium was established for the first time under the assumption that the choice of consumers takes place in accordance with their preference for a set of products, and firms maximize their profits and do not influence the formation of prices in the economic system. The last principle is called the principle of perfect competition. It may turn out that firms that have maximized their profit are zero for a certain number of firms. Such a model is ideal and its application to real systems is problematic. In [1] , another approach to the description of economic equilibrium is proposed. There, the axioms of choice and decision-making by firms based on realistic postulates are proposed. One of the principles is that the supply of firms is primary and the consumers choice is secondary. This principle, supplemented by the consistency of the proposal with the structure of the choice, made it possible to obtain algorithms for finding equilibrium states. Our approach to establishing economic equilibrium starts with proving the existence of solutions to the system of nonlinear equations, and only then the existence of economic equilibrium is established. The latter makes it possible to reduce the problem of finding equilibrium states to solving a system of nonlinear equations. The advantage of the methods developed by us is that in practically important cases the problem is reduced to a linear problem. The effectiveness of the developed methods was illustrated in the works [7] [8] [9] . Based on fairly general assumptions about the structure of supply and the structure of demand, theorems for the existence of economic equilibrium and algorithms for constructing equilibrium states have been established.
2. The Structure of Production Technology
In the contemporary economy system, the large number of participants of the economic process act interacting between themselves. The chain of economic relations between participants of the economic process and the interaction between them are not always foreseen. The main aim of the modeling of economic processes is to construct a mathematical model in that nonessential factors are neglected. A model describes a real state of an economy if it describes observable facts both qualitatively and quantitatively. Goods are all that is produced for sale. So, if it has a consumption value then the measure of the consumption value is its price. The participants of the economic process are firms and consumers. We call them economic agents. By the economic process we understand the activities of the economic agents to produce goods and services. Economic agents interact between themselves to transform one set of goods into another one with the aim to satisfy needs of society. A set of goods transformed is called input vector and the set of goods to that the input vector is transformed is called output vector. A firm is a set of the productive processes and the aim of the firm is to product goods and services for consumption by firms and consumers. A goods, for example, is consumed if it is transformed into the other goods. From this point of view any firm is a consumer. The main subject of the economic process is a person. To restore a labour force and intelligence, the person has to consume various goods. Under goods we understand the material and intelligent values, technologies, a labour force, services, and so on. Financial operations of banks, intermediary activity, trade, lease are kinds of services. In further consideration, we assume that the set of possible goods is ordered. Every set of goods we describe by a vector
, where
is a quantity of units of the i-th goods,
is a unit of its measurement,
is the natural quantity of the goods. If
is the price of the unit of the goods
,
, then
is the price vector that corresponds to the vector of goods
. The price
vector of goods
is given by the formula
. The set
of possible goods in the considered period of the economy system operation is denoted by S. We assume that S is a convex subset of the set
. Since for further consideration only the property of convexity is important, we assume, without loss of generality, that S is a certain n-dimensional parallelepiped that can coincide with
. Thus, we assume that in the economy system the set of possible goods S is a convex subset of the non-negative orthant
of n-dimensional arithmetic space
, the set of possible prices is a certain cone
, contained in
, and that can coincide with
. Here and further
is the cone formed from the nonnegative orthant
by ejection of the null vector
. Further, the cone
is denoted by
. The fact that the set of possible prices is not
obligatory will be understand when we will consider random fields discontinuous on
whose contraction on a certain cone
is yet continuous random fields of choice. We assume that the Euclidean metric is introduced in the cone
.
Definition 1. A set
is called a nonnegative cone if together with a point
the point tu belongs to the set
for every real
.
To describe an economic system, it is necessary to describe the behaviour of consumers and firms and their interaction. We put that in the economy system there are l consumers, m firms, and n kinds of goods.
Definition 2. By a technological map
, we understand a multivalued map defined on a set
taking values in the set of all subsets of the set S. Any vector
is called an input vector and its image
is called a set of plans of the technological map
. The set X is called the expenditure set and the pair
, where
,
, is called the productive process. The set
we call the set of possible productive processes for the technological map
.
Any i-th firm activity we describe by a technological map
defined on the expenditure set
and taking values in
. We introduce denotation
and the direct product of the sets
that is,
.
A wide class of compact technological maps (CTM) is introduced. For technological map from CTM class in wide sense and convex down, the Theorem guaranteeing existence of continuous strategy of firm behaviour arbitrary close, in income, to optimal one is established.
This section is devoted to the investigation of technological maps that describe production of firms. The most important among them are technological maps from the CTM class and from the CTM class in a wide sense. The notion of optimal strategy of firm behavior is introduced and the proposition 1 of the existence of optimal strategy of firm behavior for technological maps from the CTM class in a wide sense is proved.
Define a set of functions that we call income pre-functions of consumers.
Definition 3. A set of functions
,
, given on the set
with values in the set
we call income pre-functions of consumers if they satisfy conditions:
1) For every
, is a measurable mapping of the space
into the space
;
2) For every
the set
is not empty, where
;
3)
.
Definition 4. A technological map
, is the Kakutani continuous from above if for every sequence
,
,
, and for any sequence
such that
, it follows that
.
Definition 5. A technological map
, belongs to the CTM (compact technological maps) class in a wide sense if the domain of its definition
is a closed bounded convex set,
is Kakutani continuous from above, takes values in the set of closed bounded convex subsets of the set S, moreover, there exists a compact set
such that
. The technological map
, belongs to the CTM class if it belongs to the CTM class in a wide sense and, in addition,
.
Lemma 1. Let a technological map
, belong to the CTM class in a wide sense, then the set
is a closed subset of the set
.
Lemma 2. Let technological maps
, belong to the CTM class in a wide sense, and let nonnegative property vectors
, be measurable maps of the measurable space
into the measurable space
for every
, then the set
belongs to
for every
, where
The proof of Lemmas 1 and 2 see in [1] .
Let us associate with the i-th consumer a certain nonnegative vector
, that we call the supply vector of goods which the i-th consumer has at the beginning of the period of the economy operation and that is a measurable map of the space
into the space
for every
and such that
.
The vector
, we call the property vector
of the i-th consumer under the realized price vector
and the set of productive processes
.
Definition 6. Let the production of the i-th firm in the economy system be described by technological map
, the i-th consumer have property vector
, and for every
the set of productive processes
satisfy conditions:
1)
is a measurable map of the space
into the space
, for every
, where the set
;
2)
.
A measurable map
of the space
into itself for every
defined by the formula
(1)
we call productive economic process if for every
the set of values
of the map
belongs to the set
constructed in the Lemma 2, where as measurable map
, the set of supply vectors of goods of consumers
, is chosen at the beginning of the economy operation.
Definition 7. A set of functions
, defined on the set
being measurable maps of the space
into the space
for every
is named income functions if there exist a set of income pre-functions
, a productive economic process
defined on the set
and such that
belongs to the set
from the Definition 3 for every
and the equalities
1)
;
2)
(2)
are valid.
Let
, be a technological map describing the production structure of the firm. Strategy of firm behaviour is a map of the set possible prices
into the set of possible productive processes of the firm
. We denote strategy of firm behavior by
.
Definition 8. A strategy of firm behavior
, is optimal one if
Proposition 1. For technological map
, belonging to the CTM class in a wide sense an optimal strategy of firm behaviour exists.
The proof of Lemma 1 see in [1] .
Definition 9. A set of points
, where
, generates a set X, if the set X coincides with linear convex span constructed by the set of points
, that is,
where
We call the set X the linear convex span generated by the set of points
.
Remark 1. The same set X can be generated by various sets of points. If to the set of points that generates X to add any set of points that belongs to X, then they will also generate the set X. But there always exists the minimal number of points from the set of points
that generates X. These points are called extreme points.
Let
be a convex closed bounded polyhedron and the set of points
generates it. Further, let
, be a convex closed bounded
polyhedrons from
and
be a set of points that generates the
polyhedron
. Let us give a technological map
on X by the formula
(3)
where
, and by
we denote the set
The set
is the set of all points of the kind
, where the
point
runs over the set
.
Lemma 3. A technological map defined by the formula (3) takes values in the set of closed bounded and convex sets, is convex down, and Kakutani continuous from above, that is, it belongs to the CTM class in a wide sense and is convex down.
The proof of Lemma 3 see in [1] .
Lemma 4. Let
be a convex bounded closed polyhedron and the set of points
generate it. Further, let
, be convex bounded closed polyhedrons from
, and a technological map
given on X be defined by the formula (3). If the set of points
generates the set
, then
The proof of Lemma 4 see in [1] .
Lemma 5. Let
be a compact set, a technological map
maps X into bounded closed subsets of
. There exists a compact
such that
Then
is positively homogeneous subadditive continuous function on
.
The proof of Lemma 5 see in [1] .
Hereinafter, we are only interested in the restriction of
on the simplex
due to positive homogeneity of
.
Definition 10. We call a productive process
of technological map
given on X optimal one for the price vector p if
and the equality
is valid, where
In the next Lemma, we give the sufficient conditions for a technological map of the firm under the realization of that there exists a continuous strategy of firm behavior which is arbitrary close to optimal one. Further, this Lemma will be generalized onto a wide class of technological maps. The need in such assertion exists at least because the optimal behavior strategies for a quite wide class of technological maps are not continuous. In further construction, this result will play the very important role.
Lemma 6. [1] Let points
, generate convex bounded closed polyhedron X and
, be convex bounded closed polyhedrons from
generated, correspondingly, by points
. If technological map
given on X by the formula (3), then for every sufficiently small
there exists a firm behavior strategy
,
, where
is an input vector and
is an output vector such that
is a continuous map of
into
and, furthermore,
The proof of Lemma 6 the reader can find in [1] .
Let X be a convex linear span of the set of points
, the set of that is not obligatory minimal, and let
be a convex down technological map given on
belonging to the CTM class in a wide sense. We assume that every point of X is an internal point of the set
. Let us give on X a technological map
(4)
where by
we denote the set
The set
is the set of all points of the kind
, where the
point
, and
Lemma 7. The technological map
defined on X by the formula (4) is convex down and belongs to the CTM class in a wide sense if
belongs to the CTM class in a wide sense and is convex down, furthermore,
.
Proof. Prove the convexity of
for every
. Let
and
belong to
. It means that there exist
such that
, and for
and
the representations
are valid. For arbitrary
and for those i for which
do not equal zero simultaneously
where
. Due to the convexity of the set
, the point
belongs to this set too. Because
we have
for any
.
Prove the completeness of
.
Let the sequence
and
. Prove that
. From that
the existence of sequences follows
that satisfy conditions: for
and
the representations
hold. From the compactness of the considered sequences, the existence of a
subsequence
follows such that
are convergent correspondingly to
, as
, and for the limit point
of the subsequence
the representation
holds, where
The latter means that
. The closure of
follows from that
is an arbitrary limit point of the sequence
. The boundedness of
is obvious.
Prove the Kakutani continuity from above of
. Let the sequence
and
,
. Show that
. From that
, the existence of such sequences
and
follows that for
and
the representations
hold. From the compactness of the considered sequences, the existence of such
subsequence
follows that
, and
are correspondingly convergent to
and
, as
, and for
the limit points
and
of subsequences
and
, correspondingly, the representations
are valid. The latter means that
.
Prove that
is a convex down technological map. Let
Then for arbitrary
,
Due to the convexity of the set
, the point
belongs to this set too, where
for those i for which
or
do not equal zero. So,
Since
we have
for any
.
The latter means that
, or the same that
. At last,
□
Lemma 8. Let points
generate a convex bounded closed polyhedron
and a technological map
, given on X, be defined by the formula (4). Then
Proof. Any points
and
can be represented in the form
(5)
Substituting the representations for x and y into the expression
we obtain
There hold the inequalities
Therefore, for any
and
or
Prove the inverse inequality. It is obvious that
. Therefore,
Taking maximum over all
from the left and right side of the last inequality, we obtain the needed inequality. □
Definition 11. A set of points
, generates a set
if the set X is the closure of the set of points of the form
where
Lemma 9. Let
be a convex bounded closed set whose every point is internal for a set
and
be dense in X set of points that generate it. If the technological map
is given by the formula (4) on the set
generated by the first k points
from the set of points
, that generate X, then
Proof. We assume that the set of points
are ordered and the set
is generated by the set of points
. There holds the inclusion
where
So, the sequence of functions
is monotonously non decreasing, that is,
. Consider
. Due to the
continuity of the function
in argument y and the compactness of the set
, there exists a point
such that
From the convexity down of
, the function
is a convex up function of the argument x and so it is continuous one by argument x on the set X. On the basis of the Weierstrass theorem,
Consider the sequence
and show that for every
where
Because the sequence of points
of the set X is dense in X, there exists subsequence
of this sequence that converges to a point
in which
the supremum is realized
. It is evident
that for
there holds the inequality
Tending from the beginning k and then m to the infinity, we obtain
On the other hand,
Therefore,
. □
Let
be a convex down technological map from the CTM class in a wide sense defined on
. Cover the set P by balls
of a radius
. Thanks to the compactness of P, there exists a finite subcovering with the center at the points
, that is,
Denote by
the point of the set
, in which the maximum of the problem
is reached, where the set of points
generates the set
.
Let
be a set of points that generates the set
,
and
be a technological map given on the set X by the formula (4). Define on X a technological map
(6)
where by
we denote the set
The set
is the set of points of the form
, where the point
and the vector
runs over the set
Owing to the points
generate the set
, and
, then
Thus,
.
Lemma 10. Let technological maps
and
be given, respectively, by the formulas (4) and (6) on the set X generated by the set of points
that non obligatory is minimal and every point of the set X be an internal for the set
, on which a convex down technological map
from the CTM class in a wide sense is given. Then, for every
, there exists
such that
Proof. Let us show the equality
At first, show that
This equality follows from the Lemma 8 and the fact that
At last, on the basis of the Lemma 4
Since
we have
So,
The needed equality is proved. Let us estimate the difference
Since
and
satisfy conditions of the Lemma 5, then for
,
,
. Choosing
such that for
given
the inequality
would be valid, we obtain the proof of the Lemma. □
Now, prove the main statement of this Section.
Theorem 1. [1] Let X be a bounded closed convex set whose every point is internal for
and
be a convex down technological map from the CTM class in a wide sense given on a convex compact set
. Then, for every sufficiently small
, there exists a continuous firm behavior strategy
,
such that
where
Proof. Let
be a dense countable set of points that generates X and such that it contains a dense set of extreme points of X. Further, let
be a polyhedron generated by the first k points
. There hold such enclosures
. On the basis of the Lemma 9, the sequence
of continuous functions on P
is monotonically
non decreasing and converges to a continuous function
. According to the Dini theorem, the sequence
converges to
uniformly. Therefore, there exists a number
such that for every
From the Lemma 10
for sufficiently small
, where
According to the Lemma 6, there exists a continuous firm behavior strategy
,
,
such that
The latter proves the Theorem. □
3. Equilibrium State Existence
This section examines the conditions for the existence of economic equilibrium in the presence of production of goods. Production is described by technological mappings belonging to the class of compact technological mappings.
We suppose that economy system models described non-aggregately behavior strategies of consumers choice (realizations of random fields of consumers choice) are not continuous functions on the simplex P. If the consumer consumes not all the goods the economy system produces, but some part of them, then components of the demand vector corresponding to goods he does not consume equal zero. As a result, the demand vector of such consumer can not be given unambiguously on the whole simplex P such that to be continuous on this simplex. To describe discontinuous behavior strategies of consumers choice, define random fields of consumers choice not on the whole cone
, but on a certain cone
being a subcone of the cone
on which the conditions of the Theorem 1.4.6 and the Theorem 1.4.7 on the existence of random
fields of consumers choice are valid [1] . Let
be a certain
-dimensional matrix satisfying conditions:
, and
.
Introduce the cone
built by the rule
(7)
First, let us consider the case of all insatiable consumers. Suppose random fields of information evaluation by consumers satisfy the condition: for every i-th consumer a random field of information evaluation by the i-th consumer
on a probability space
satisfies the
inequality
where the real numbers
,
, and components
if and only if
.
Under these additional assumptions about the random fields
,
, and assumptions about the matrix C on the above built cone
(with the rest conditions of Theorems 1.4.4 and 1.4.6 hold (see [1] ), there exist random fields of consumers choice and decisions making by firms for insatiable consumers.
In what follows, we assume the conditions the above stated hold for the random fields on the above built cone.
Note that if a certain components of the vector
equal zero, then the i-th consumer does not consume goods numbered by these components.
Let
be a certain continuous realization of a random field
, and
be a continuous realization of a random field
Therefore,
for a certain
and
. Denote by
Introduce the set
and the next notations
Theorem 2. Let technological maps
, describing the economy system production be convex down, belong to the CTM class, and let a productive economic process
, a family of income pre-functions
, and property vectors
, be continuous maps of variables
, where
is a cone given by the formula (7), and also let
where a does not depend on
. Assume that random fields of information evaluation by consumers and decisions making by firms satisfy the conditions of the Theorem 1.4.6 [1] and the productive economic process
satisfies the condition
(8)
where
If the set
is non-empty for some
, the inequality
holds, where
then for every continuous demand matrix
and continuous realization of random field of decisions making by firms
on
, i.e., with probability 1, there exists a price vector
corresponding to them satisfying the set of equations
(9)
Proof. On the closed bounded convex set
, let us consider the non-linear operator
where
Under the conditions of the Theorem,
, and
. The
operator
transforms the set
into itself and is a continuous map. It is sufficient to check the inequalities
and show the continuity of
. First, prove the continuity of
. In view of the continuity of
for every realization and the condition of the Theorem,
So, we have that
nowhere vanishes on the set
. From the
fact that
, we have that
is a continuous function of
and
is a continuous map on
. Find lower bound for
. We have
Therefore,
is a continuous map on
. For
, the upper
bound
is valid. Finally, show that
Really,
Because of the assumptions for the matrix elements
, for
So,
By the Schauder Theorem [10] , there exists a fixed point of the map
. This point is also a fixed point for the map
. Really, as
is a fixed point of the map
, we have
Multiplying by
the last equality and summing up over k, we have
However,
Reducing by
, in view of the inequality
, we obtain
. The last means that
solves the set of Equation (9). □
Establish sufficient conditions for the previous Theorem conditions to hold.
Lemma 11. If the matrix elements
satisfy the conditions stated above and the conditions of the Theorem 2 are valid and also
then for all
satisfying the inequalities
the set
is non-empty and the inequality
holds.
Proof. There hold bounds
Finally, the set
is non-empty because it contains the vector
.
□
Theorem 3. Let technological maps
, describing the economy system production structure, be convex down, belong to the CTM class, and let a productive economic process
, a family of income pre-functions
, and property vectors
, be continuous maps of variables
, where
is a cone given by the formula (7), and also let the conditions of the Lemma 11 hold.
Suppose that random fields of information evaluation by consumers and decisions making by firms satisfy the conditions of the Theorem 1.4.6 [1] and a productive economic process
satisfies the condition
(10)
where
If
, then for every continuous demand matrix
and continuous realization of random field of decisions making by firms
on
there exists a strictly positive price vector
corresponding to them and satisfying the set of equations
(11)
where
Proof. Denote
On the closed bounded convex set
, where
satisfies the conditions of the Lemma 11, let us consider the non-linear map
where
The map
transforms the set
into itself and is a continuous map. It is sufficient to check the inequalities
and show the continuity of
. First, let us prove the continuity of
. In view of the continuity of
for every realization and the condition of the Theorem,
Thus,
nowhere vanishes on the set
. Therefore,
is a
continuous map on
.
There hold the estimates
Therefore,
is a continuous map on
.
Finally, show that
Really,
In view of the assumptions about matrix elements
, for
Therefore,
By the Schauder Theorem [10] , there exists a fixed point of the map
. This point is also a fixed point for the map
. Really, as
is the fixed point of the map
, we have
Multiplying the last equality by
and summing up over k, we have
However,
Reducing by
, in view of
, we obtain
. The latter means that
solves the set of Equation (11). As the
price vector
solves the set of Equation (11) and the conditions of the Lemma 11 hold, the inequalities for components
hold, where
□
Theorem 4. Let the conditions of the Theorem 2, of the Lemma 11 and the
inequalities
, hold. Then there exists an equilibrium price
vector
, under which the demand does not exceed the supply, i.e., the set of inequalities holds
(12)
Every equilibrium price vector satisfies the set of Equation (9).
Proof. Consider the auxiliary set of equations
(13)
built after the set of Equation (9). Every component of the solution
to the set of Equation (13), by the Theorem 3, is strictly positive.
As
solves the set of Equation (13) and
, we obtain the set of inequalities
(14)
The sequence
, when
, is compact one, because it belongs to the set
. Due to the continuity of
on the set P and the inequality
one can go to the limit in the set of Inequalities (14). Denote one of the possible limit points of the sequence
by
. Then
solves the set of inequalities
(15)
It is obvious that the vector
belongs to the set
and solves the set of Equation (9). □
4. Economy Equilibrium with Fixed Profits of Consumers
We introduced a model of consumption economy with fixed profits and studied it in the papers and monographs [1] [11] [12] [13] . Under rather simple restrictions on the consumption structure, supply vector, and consumers profits, we proved the existence Theorem for equilibrium price vector. Suppose that in a certain economic system there are n kinds of goods and l consumers. Consider that the i-th consumer has fund
. On the economic system market, goods supply vector has the form
The set of possible price vectors is a cone
, being a subcone of the
cone
. Let us build the cone
. Let
be a certain non-negative
matrix of the dimension
satisfying conditions
The matrix C determines the cone
by the rule
(16)
Consider the case of insatiable consumers. Suppose that random fields of information evaluation by consumers satisfy the condition: for every i-th consumer the random field of information evaluation
by the i-th consumer on a probability space
, satisfies the inequality
(17)
where
, and components
of the random field of information evaluation by the i-th consumer
satisfy the condition:
if and only if
.
Suppose that consumers operate independently and their random fields of choice have the form
In the next Theorem, we assume that the above formulated conditions hold for random fields of consumers choice on the cone built above.
Note that if certain components of the vector
equal zero, then the i-th consumer does not consume goods numbered by these components.
Let
be a continuous realization of the random field of information evaluation by consumer
Therefore,
for some
. As earlier, denote
components of the demand vector
Introduce into consideration a set
and notations
.
Theorem 5. Suppose that random fields of information evaluation by consumers on the cone
, given by the Formula (16), are continuous with probability 1, satisfy the Condition (17), and a number
satisfies the inequality
Then for every continuous on
demand matrix
, i.e., with
probability 1, there exists a corresponding price vector
satisfying the set of equations
(18)
Proof. Introduce into consideration a map
and show that it maps the non-empty set
into itself.
If
satisfies the conditions of the Theorem, then the set
is not empty and the inequality
holds, where
Check the validity of the inequalities
Really,
Because of assumptions about the matrix elements
, for
Therefore,
The map
is a continuous map of the convex compact set
into itself. By the Schauder Theorem [10] , there exists a fixed point of the map
.
□
Theorem 6. Assume that random fields of information evaluation by consumers on the cone
given by the Formula (16) are continuous with probability 1, satisfy the Condition (17), and a number
satisfies conditions of the
Theorem 5. If
, then for every continuous demand matrix
on
, i.e., with probability 1, there exists corresponding it a
strictly positive price vector
, solving the set of equations
(19)
where
Proof. Introduce into consideration a map
and show that it maps the non-empty set
into itself.
If
satisfies the conditions of the Theorem, then the set
is not empty and the inequality
holds. Check the validity of the inequalities
Really,
Due to assumptions about the matrix elements
, for
Therefore,
The map
is a continuous map of the convex compact set
into
itself. By the Schauder Theorem [10] , there exists a fixed point
of
the map
whose components satisfy inequalities
where
□
Theorem 7. Let the conditions of the Theorem 5 and the inequalities
hold. Then there exists an equilibrium price vector
for which the demand does not exceed the supply, i.e., the set of inequalities
(20)
hold. Every equilibrium price vector satisfies the set of Equation (18).
Proof. Consider the auxiliary set of equations
(21)
built after the set of Equation (18), where
Every component of a solution
for the set of Equation (21) is strictly positive by the Theorem 6. From the fact that the strictly positive vector
satisfies the set of Equation (21), the validity of the set of inequalities
(22)
follows. The sequence
for
is compact because it belongs to the
compact set
. Due to the continuity of
on the set
and the
inequality
one can go to the limit in the set of Inequalities (22), as
. Denote one of the possible limit points of the sequence
by
. Then
solves the set of inequalities
(23)
It is obvious that the vector
belongs to the set
.
□
5. Conclusion
Section 1 lists the main results. In Section 2, the theory of technological mappings from the CTM class is constructed, which contains the well-known technological mappings of Leontiev and Neumann. The main statement of this section is the Theorem of the existence of a continuous strategy of the firm behavior as arbitrarily close in terms of profit to the optimal one. Section 3 contains a number of Theorems, the main content of which is the statement about the existence of economic equilibrium under fairly general assumptions about the structure of supply and demand. Section 4 contains theorems on the existence of economic equilibrium under the condition of arbitrary assumptions about the structure of supply and demand and under the condition that each consumer has a positive income.
NOTES
1This work was partially supported by the program of fundamental research of the department of physics and astronomy of the national academy of sciences of Ukraine “construction and research of financial market models using the methods of non-equilibrium statistical physics and the physics of nonlinear phenomena” N 0123U100362.