Abstract
To study an uncertain case of a control problem, we consider the symmetric F-n-NLS which is induced by a dynamic norm inspired by a random norm, distribution functions, and fuzzy sets. In this space, we consider a random multi-valued equation containing a parameter and investigate existence, and unbounded continuity of the solution set of it. As an application of our results, we consider a control problem with multi-point boundary conditions and a second order derivative operator.
MSC:
47C10
1. Introduction
Consider the random operator . A natural generalization of parametric random equations of the form , in which is a element of a probability measure space, is the multi-valued form [1],
In regards to solutions, there are many approaches available in the literature, for example the principal eigenvalue-eigenvector method, the monotone minorant method [2,3] and topological degree. The idea in this paper is to use the topological degree for random multi-valued mappings and the method of evaluating solutions. The main idea is presenting an uncertain case of a control problem. To achieve this aim, we use a special space, i.e., symmetric F-n-NLS, that has a dynamic situation and a parameter , which can be time, which enable us to consider different cases. We note this kind of space induced by a dynamic norm which is inspired by random norms, probabilistic distances and fuzzy norms was studied; see [4] for details and applications. Our results can be applied in uncertainty problems, risk measures and super-hedging in finance [5].
For the random multi-valued operator , the following sets
or
are solutions of (1). In this paper, we consider a control problem with multi-point boundary conditions and a second order derivative operator as
where , and . In Section 2, we introduce our special space, i.e., symmetric F-n-NLS and present some basic results which we need in the main section. In Section 3, we prove some properties of random multi-valued operator. In Section 4, we present an application of our results for a fuzzy control problem.
2. Preliminaries
Here, we let , , and .
A mapping , whose -level set is denoted by
is said to be a fuzzy real number if it satisfies the following:
- (i)
- is normal, i.e., there exists such that ;
- (ii)
- is upper semicontinuous;
- (iii)
- is fuzzy convex, i.e., , for each such that and ;
- (iv)
- For each , , where and is compact.
Let the set contain all upper semicontinuous normal convex fuzzy real numbers. contains all non-negative fuzzy real numbers of . For each , we can define
so and can be embedded in .
A partial order ⪯ in is defined as follows: iff for each , and where and . The strict inequality in is defined by iff for each , and (see [6,7,8]).
The arithmetic operations ⊕, ⊖, ⊙ and ⊘ on are defined by
Definition 1.
Let ℧ be a real linear space over with dim . Suppose is a mapping and are symmetric, nondecreasing mapping satisfying
Write
for , and suppose that for every linearly independent vectors , there exists independent of such that for each , one has
The quadruple is said to be a symmetric fuzzy n-normed linear space (F-n-NLS) in the sense of Felbin [8] and is a fuzzy n-norm if
- (N1)
- iff are linearly dependent;
- (N2)
- is invariant under any permutation of ;
- (N3)
- for any ;
- (N4)
- ;
- (i)
- whenever , and ,
- (ii)
- whenever , and ,
Now, we consider a symmetric F-n-NLS in the sense of Narayanan-Vijayabalaji [9] and next we show a relationship between them.
Definition 2
([9]). Assume that ℧ is a linear space and ∗ is a continuous t-norm. Let the fuzzy subset η of with dim satisfy
- (FN1)
- For all with , ;
- (FN2)
- For all with , for iff are linearly dependent;
- (FN3)
- is invariant under any permutation of ;
- (FN4)
- For all with ,
- (FN5)
- For all with ,
- (FN6)
- is left continuous;
- (FN7)
- .
Thus, the triple is a symmetric F-n-NLS (see [10,11,12]).
A complete symmetric F-n-NLS is called symmetric F-n-BS.
Theorem 1
([9,13,14,15]). Let be a symmetric F-n-NLS in which and
- (FN8)
- for all implies are linearly dependent.
Define
Then is an ascending family of fuzzy n-norms on ℧.
These fuzzy n-norms will be called the ϵ-n-norms on ℧ corresponding to the fuzzy n-norm on ℧.
We note that some applications can be found on [16,17].
Remark 1
([18]). Let be a Euclidean fuzzy norm (Euclidean fuzzy normed spaces were introduced by the authors in [18]). Then are linearly independent iff , for any .
By the above remark, we have that, are linearly independent iff
Consider the probability measure space and let and be Borel measurable spaces, where U and S are symmetric F-n-BS. If for every in U and , we say is a random operator. Let be the family of all subsets of S. The mapping is said to be random multi-valued operator. A random operator is said to be linear if almost everywhere for each in U and are scalers, and bounded if there exists a nonnegative real-valued random variable such that
almost everywhere for each in U, and .
Let be a symmetric F-n-BS over with dim and ordering by the cone , i.e., is a closed convex subset of such that for , , and iff for with and . For nonempty subsets of we write (or, ) iff for every , we can find a which (or, ) for . We say is a normal cone if we can find a constant where for implies . We note in this paper, we consider as a normal cone with . Furthermore,
Consider the open convex subset of , and let , and , where is boundary of in . The mapping is said to be compact if is relatively compact for any bounded subset of , where , for any . We say a random multi-valued operator has the upper semi-continuity property (in short, u.s.c.rmvo) if
where and . Further, if for all and , the random fixed point index of in with respect to is defined which is an integer denoted by .
Lemma 1.
[2] Let be a compact u.s.c.rmvo. Then
- 1.
- if there exists such that for all , and .
- 2.
- if for all and .
The following results are needed later to obtain a generalization of [19].
Lemma 2.
[20] Assume that is a u.s.c.rmvo, with and . Thus, .
Lemma 3.
[19] Let be a compact u.s.c.rmvo with for all and . Then, .
3. Random Multi-Valued Operator
Lemma 4.
Let be a compact u.s.c.rmvo and be open with . Additionally,
- 1.
- , for any , for some implies ,
- 2.
- if γ is sufficiently large and .
Then .
Proof.
From the second condition in Lemma 4 we can find such that for all and . Define
We first observe that . Furthermore,
for any . Since is compact, without loss of generality we may assume that when and . From (5) by Lemma 2 it follows that
This contradicts the first condition in Lemma 4. Thus, there exist such that for all and , where
Using Lemma 3 we have
Using Lemma 1 implies that . Thus, , and we deduce , for each .
Next, for every and , there exists with . Consider the random multi-valued operator defined by
Now, we prove
Assume the contrary, that
Then, the random fixed point index of is well defined, for each . If
then, by Lemma 3 we obtain
for each , a contradiction. Then, we can find a satisfying
for each . Similarly, there is a with , which shows (6) is not true, and completes the proof. □
Let be asymmetric F-n-BS over with dim ordered by the normal cone . Suppose that , the embedding is continuous, and is a compact u.s.c.rmvo. Assume is a compact random linear operator satisfying such that , for each .
Theorem 2.
Let
- 1.
- , for any , for some implies ;
- 2.
- we can find positive numbers and a random linear operator with , for any , for some such that
- (a)
- andfor all and ,
- (b)
- for all , , and
- (c)
- we can find an increasing map ( on the second part) such thatsuch that withimplies
Then
is an unbounded continuous branch emanating from 0, for each .
Proof.
Suppose is open and bounded where . We use Lemma 4 with to show , for any . Clearly, condition 1 of Lemma 4 holds. Assume that satisfies (11), so , hence, , for any , for some . By 2(a) and 2(b) we have
and
for each . For sufficiently large , (13) and (14) we conclude that
which combining with (12) gives
for each . If , for some . From (15), (11) it follows that for all and , where . Applying Lemma 1 we obtain , here , and therefore , so condition 2 of Lemma 4 holds. The proof is complete. □
4. Applications
In this section, we study an uncertain case of a control problem. For it, we consider the compact u.s.c. rmvo and the continuous map . We consider the following control problem which contains a parameter:
where , and .
Denote for every , and let
Let , resp., , be the symmetric F-n-BS of all continuous, resp., continuously differentiable, functions on . Denote
and
Let be a random linear operator () defined by
for each and . We solve
where the random multi-valued operator is defined by
for each and , since it is equivalent (17).
Theorem 3.
Let . Suppose we can find , and such that
- 1.
- ,
- 2.
- ,
- 3.
- .
Thus, the positive fuzzy solution set for (18) is unbounded continuous in , originating from 0.
Proof.
Use Theorem 2 and cones
and
Then, and , resp., are symmetric F-n-BSs with the norms
and
Suppose , and satisfies , so we can find such that
for each and . Then . By [21], we can conclude that the compact random linear operator have an eigen-value and a positive eigen-map . Define the random linear operator on , by . From condition 2. we have
for each ; here . When in which and , then we can find a number such that on . For , is a concave function with and , and we have , for each . From Fubini’s Theorem it follows that
for each . Consequently, there is constant satisfying
for each . Now, assume with
This implies
for each . Now, and n are constant, not depending on and . Using Theorem 2 implies that
Therefore we can choose such that
Furthermore, for , we have
Since we have condition (2c) of Theorem 2 satisfied with the function . □
5. Conclusions
In this paper, using a generalized norm which has a dynamic case and is inspired by a random norm and fuzzy sets, we introduced a symmetric F-n-NLS to study the existence, and unbounded continuity of the solution set of random multi-valued equation containing a parameter. These results allow us to consider an uncertain control problem. The applied procedure can hopefully be useful in the future to consider other types of fuzzy control problems.
Author Contributions
R.S., methodology and project administration. T.A., writing—original draft preparation. D.O., methodology, writing—original draft preparation and project administration. F.S.A., writing—original draft preparation and project administration. All authors have read and agreed to the published version of the manuscript.
Funding
The authors extend their appreciation to the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University (IMSIU) for funding and supporting this work through Research Partnership Program no RP-21-09-08.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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