Abstract
This work’s theorems and corollaries present new third-order fuzzy differential subordination and superordination results developed by using a novel convolution linear operator involving the Gaussian hypergeometric function and a previously studied operator. The paper reveals methods for finding the best dominant and best subordinant for the third-order fuzzy differential subordinations and superordinations, respectively. The investigation concludes with the assertion of sandwich-type theorems connecting the conclusions of the studies conducted using the particular methods of the theories of the third-order fuzzy differential subordination and superordination, respectively.
Keywords:
meromorphic p-valent function; Gaussian hypergeometric function; Hurwitz–Lerch Zeta function; convolution; linear operator; third-order fuzzy differential subordination; third-order fuzzy differential superordination MSC:
30C45; 30C80; 33C05
1. Introduction
The present work focuses on advancing the recently started study of the dual theories associated with the newly introduced generalizations of third-order fuzzy differential subordination and superordination. The motivation of the research is to use the recently developed techniques that are specific to the two dual fuzzy theories for obtaining new outcomes related to third-order fuzzy differential subordination and superordination and to further connect the dual results through sandwich-type results, as familiar when investigating dual theories in the field of geometric function theory.
In 2024, third-order fuzzy differential subordination and superordination were proposed [1,2] in an attempt to improve upon the second-order fuzzy differential subordination and superordination ideas that had already been well established. Many classical third-order differential subordination and superordination results are currently being obtained that could be enhanced to fit the new fuzzy differential subordination and superordination theories. For instance, third-order differential subordinations and superordinations are obtained through a fractional differential operator in [3], a seven-parameter Mittag–Leffler operator in [4], and a convolution operator in [5]. The motivation behind introducing the concepts of third-order fuzzy differential subordination and superordination, as explained in the articles first revealing them [1,2], was to develop the concepts of third-order fuzzy differential subordination and superordination by broadening current ideas related to second-order fuzzy differential subordination and superordination. Since different types of operators added into the studies on third-order differential subordination and superordination theories enhanced the relevance of the outcomes, the use of such operators is considered beneficial for developments concerning the particular forms of third-order differential subordination and superordination when they are fuzzy in nature. This is the motivation behind the study presented in this paper. Hence, to obtain the new results of the present investigation, in this work, a new convolution operator is introduced and applied in the particular fuzzy contexts of the two dual theories of third-order fuzzy differential subordination and superordination.
Similar to how the classical theory of third-order differential subordination [6] broadened the theory of second-order differential subordination [7,8], the concepts associated with third-order fuzzy differential subordination theory emerged recently in [1], carrying on the idea of improving the theory of second-order fuzzy differential subordination [2]. In their work [1], the authors presented the main ideas of the third-order fuzzy subordination extension as well as the key concepts to be used for studies related to this specific type of fuzzy differential subordination theory, such as the admissible functions class and some fundamental theorems. Motivated by the intention of moving forward with the advancement of the theory of second-order fuzzy differential superordination [9] using the fundamental pattern set for the fuzzy differential superordination theory [10], the dual concept associated with third-order fuzzy differential superordination theory also recently emerged [11]. In [11], the authors studied the dual problem of third-order fuzzy differential superordination by introducing the fundamental ideas that characterize this concept, the admissible functions class, and certain basic theorems that are to be used for further development on the topic.
The present investigation follows the pattern set for second-order fuzzy differential subordination and superordination. This new type of differential subordination and superordination originally emerged motivated by the idea seen in many fields of mathematics that have tried to incorporate the fuzzy set notion introduced by Lotfi A. Zadeh [12]. The use of different types of operators produced the first published studies on the development of fuzzy differential subordination and superordination theories [13,14,15]. The application of different operators in fuzzy differential subordination and superordination theories continues to generate multiple new results at this time, as evidenced in recently published articles such as [16,17,18]. The class of meromorphic functions has also been recently targeted by recent investigations on third-order differential subordinations as seen in [19] and on fuzzy differential subordination, as in [20].
The present investigation considers a new linear operator introduced by the convolution applied to the operator introduced by El-Ashwah and Bulboacă [21] by using Hurwitz–Lerch Zeta function and the Gaussian hypergeometric function. The use of the new operator is inspired by the research presented above showing how the use of different types of operators has enhanced our knowledge regarding second-order fuzzy differential subordination and superordination theories. It must also be considered that the line of research involving third-order fuzzy differential subordination and superordination is new and needs to be explored. Hence, the addition of operators to the investigations must prove beneficial for the development of new fuzzy dual theories. It is shown that the new operator generalizes previously investigated operators. The purpose of this endeavor is to establish third-order fuzzy differential subordination and superordination properties of meromorphic multivalent functions by applying this new operator.
Since only papers introducing the concepts [1,2] have been published so far on third-order fuzzy differential subordination and superordination dual concepts, the present paper is essential for the development of these newly emerging topics. The previously established results used for this investigation are recalled in the next section, and the new third-order fuzzy differential subordination and superordination findings are revealed in the section that follows.
2. Materials and Methods
Denote by the class of analytic functions in with being the unit disk of the complex plane with and The known subclasses of are of utmost importance for this study:
where
where with and and
is the class of normalized convex functions.
Furthermore,
With is subordinate to or is superordinate to , written or if there exists a Schwarz function satisfying and such that If , then and
Meromorphic multivalent functions are gathered under the symbol defined as follows:
with the punctured unit disc
Having two functions written as
we define the convolution of and as
The investigation presented in this paper is initiated with the use of the operator [21] defined by using Hurwitz–Lerch Zeta function as follows:
It was proved in [21] that for all and the following relations are true:
⋮
⋮
In order to introduce the new operator, another intermediate tool is needed. The following function is developed:
where is the Pochhammer symbol defined as follows:
It can be seen that
where
is the Gaussian hypergeometric function.
Using the definition for the convolution of meromorphic multivalent functions and the definition of the operator given in (2), by letting
we have
As an application of the operator , a new operator is introduced by
The operator satisfies
and
We note that
- (i)
- (see Miller and Mocanu [22], p. 389);
- (ii)
- , (see Aqlan et al. [23]);
- (iii)
- (see El-Ashwah and Aouf [24]);
- (iv)
- (see El-Ashwah [25]).
The following notion is well known in third-order differential subordination theory.
Definition 1
([6], p. 441, Definition 2). Denote by the set of all functions that are analytic and injective on where
and that are such that for . is called the exception set, and the subclass of when is denoted by .
Intended to generalize the classical concept of subordination, fuzzy subordination was initiated using the following definitions in [2]:
Definition 2
([2]). A fuzzy subset of X is a pair , where is known as the membership function of the fuzzy set and is called the support of the fuzzy subset .
Let
and
Definition 3
([2]). Let and , is fuzzy subordinate to and written as if
Next, the class of admissible functions is defined as follows:
Definition 4
([6]). Let be a function, and . Functions are called admissible functions and belong to the so-called class of admissible functions denoted by if the admissibility condition
is satisfied when
where , and
Further, the notions of fuzzy best dominant and subordinant are recalled, introduced as extensions of the well-known notions of best dominant and best subordinant from the classical theories of classical differential subordination and superordination, respectively.
Definition 5
([11], Definition 5). Let Ω be a set in , Denote by the set of functions satisfying the condition
where
where , and . Condition (10) is called the admissibility condition.
Definition 6
([1], Definition 3.2). Consider , and let A function is called a solution for a third-order fuzzy differential subordination if it satisfies
i.e.,
A function is said to be a dominant of the solutions of a third-order fuzzy differential subordination if it satisfies the fuzzy subordination for all solutions of the third-order fuzzy differential subordination (11). The fuzzy best dominant is a dominant that satisfies the fuzzy subordination for all dominants of (11).
Definition 7
([11], Definition 6). Consider , and let A function satisfying
i.e.,
is called the solution of fuzzy differential superordination (12).
The following established results will be used in the proof of the original results contained in the following two sections.
Lemma 1
([1], Theorem 3.4). Let with . Consider and a function for which
where , and . If Ω is a set in , satisfying
then
Lemma 2
([11], Theorem 1). Let , a function given by , and satisfying
where , , and ; if and are univalent in , then
or equivalently,
implying that
With this research context established, the following two sections describe the new third-order fuzzy differential subordination and superordination results, respectively.
3. Results
3.1. Third-Order Fuzzy Differential Subordination Advancements
Throughout the study, unless otherwise indicated, we will assume that , and .
This section presents new results on third-order fuzzy differential subordination. The following definition of the class of admissible functions is used for this purpose:
Definition 8.
Let and . The functions belong to the class of admissible functions if the admissibility condition
is satisfied whenever
where , , and .
The first new finding is stated and proved as Theorem 1 below. The third-order fuzzy dominant of certain third-order fuzzy differential subordinations involving the operator presented in Relation (5) applied to meromorphic multivalent functions can be obtained using the following theorem.
Theorem 1.
Let . If and satisfy
then
which implies
or
Proof.
Consider as follows:
By differentiating (20) and using the property of the operator given in (6), we obtain
Similarly, by differentiating (21) and using the property seen in (6) alongside Relation (20), we write
Further, by differentiating (22) and using the property seen in (6) together with the previously obtained Relations (21) and (22), we obtain
Next, the transformation from to is expressed as
and
Let
Using Lemma 1 and (20)–(27), we have
Hence, (18) leads to
Additionally, applying (24)–(26), we obtain
and
Thus, for , the admissibility condition given by Definition 8 is equivalent to the one given for in Definition 4. Consequently, by utilizing (17) and Lemma 1, we deduce or, equivalently,
i.e.,
Hence, the proof is completed. □
Example 1.
By taking and in Theorem 1, we obtain that
is analytic in and
so
or
When the behavior of on is unknown, Theorem 1 immediately leads to the following result.
Corollary 1.
Let and let with . Let for certain when . If and satisfy
then
implies
Proof.
Following Theorem 1, we obtain
Now, the following fuzzy subordination property can be used in order to conclude the proof of Corollary 1:
This completes the proof of Corollary 1. □
When is a simply connected domain, with for a certain conformal mapping of onto , the notation designates the class . The following two results are direct outcomes of Theorem 1 and Corollary 1.
Theorem 2.
Let . If and satisfy
then
implies
In other words,
Corollary 2.
Let and let with . Let for certain when . If and satisfy
then
implies
The fuzzy best dominant of the fuzzy differential subordination (18) or (34) is provided by our next proved result.
Theorem 3.
Proof.
A new admissible functions class is introduced for developing the new results proved in the following theorem:
Definition 9.
Let and . The functions belong to class of admissible functions if the admissibility condition
is satisfied whenever
where , , and .
Theorem 4.
Let . If and satisfy
then
implies
Proof.
Let
By differentiating (39) and using the property of the operator given in (7), we write
Further, by differentiating this last equation and using again the property seen in (7), we obtain
By differentiating now this last relation and using again the property given by (7), we have
Further, the transformation from to is expressed as
and
Let
Using Lemma 1, (39)–(42), we have
Hence, (43) leads to
Using (41) and (42), we obtain
and
Thus, for , the admissibility condition given by Definition 9 is equivalent to the one given in Definition 4 for . Consequently, by utilizing (37) and Lemma 1, we obtain or, equivalently, —i.e.,
This completes the proof of Theorem 4. □
Example 2.
By taking , and in Theorem 4, we obtain that
is analytic in and
so
or
When the behavior of on is unknown, Theorem 4 immediately leads to the following result.
Corollary 3.
Let and let with . Let for certain when . If and satisfy
then
implies
Proof.
Following Theorem 4, we obtain
Now, the following fuzzy subordination property can be used in order to conclude the proof of Corollary 3:
The proof is now complete. □
When is a simply connected domain, with for a certain conformal mapping of onto , the notation designates the class . In this case, Theorem 4 and Corollary 3 provide the following immediate consequences.
Theorem 5.
Let . If and satisfy
then
implies
Corollary 4.
Let and let with . Let for certain when . If and satisfy
then
implies
The fuzzy best dominant of the fuzzy differential subordination given in (38) or (46) is provided by our next proved result.
Theorem 6.
3.2. Third-Order Fuzzy Differential Superordination Advancements
This section presents new results regarding third-order fuzzy differential superordination. The following definition of the class of admissible functions is used for this purpose:
Definition 10.
Let , , and . The functions belong to the class of admissible functions if the admissibility condition
is satisfied whenever
where , , and .
Theorem 7.
Let . If and satisfies
and
is univalent in , then
implies
Proof.
Let be given by (20) and be given by (27). Since (28) and (53) yield
For , we conclude from (27) that the admissible condition seen in Definition 10 is equivalent to the one expressed in Definition 8 for . Thus, by utilizing Lemma 2 and the conditions in (52), we establish that
or, equivalently,
Hence, the proof is completed. □
Example 3.
By taking , and in Theorem 7, we obtain
If
is analytic in and
then
or
When is a simply connected domain with for a certain conformal mapping of onto , the notation designates the class . Using the same techniques as in the previous section, Theorem 7 yields the following result.
Corollary 5.
For a correctly chosen , it is established by the following theorem that the best subordinant for (58) exists.
Theorem 8.
Proof.
The proof of Theorem 3, which is similar to the proof of Theorem 8, is not given in detail. □
A new class of admissible functions, , is introduced for obtaining new fuzzy superordination results.
Definition 11.
Let , with and . Functions belong to the class of admissible functions if the admissibility condition
is satisfied, whenever
where , , and .
Theorem 9.
Let . If and satisfy
and
is univalent in , then
implies
Proof.
Let be given by (39) and be given by (42). Since (43) and (62) yield
For , we conclude from (42) that the admissible condition seen in Definition 2 is equivalent to the one expressed in Definition 8 for . Thus, utilizing Lemma 2 and the conditions in (61), we establish that
or, equivalently,
Hence, the proof is concluded. □
When is a simply connected domain with for a certain conformal mapping of onto , the notation designates the class . Using the same techniques as in the previous section, Theorem 9 yields the following result
Corollary 6.
For a suitable choice of , it is established by the following theorem that the fuzzy best subordinant for (63) exists.
Proposition 2.
Proof.
As it is similar to the proof of Theorem 6, the proof of Theorem 2 is not given in detail. □
Example 4.
By taking , and in Theorem 8, we obtain
If
is analytic in and
then
or
3.3. Sandwich-Type Advancements
Combining Theorems 2 and 5, we write
Proposition 3.
The following sandwich-type result can also be obtained by combining Theorems 5 and 6:
4. Discussion
The results of the present investigation enhance the recently started research on third-order differential subordination and superordination theories. The emergence of fresh insights for these relatively new lines of study is what makes this work innovative. The first part of the investigation provides means to determine the third-order fuzzy dominant of several third-order fuzzy differential subordinations involving the operator given in relation (5) applied to meromorphic multivalent functions. Then, when the third-order fuzzy differential subordination admits of the third-order fuzzy best dominant, it is made clear how to find it. In the following part of the investigation, using the operator given in relation (5) applied to meromorphic multivalent functions, dual results are obtained regarding means for obtaining the third-order fuzzy subordinant of certain third-order fuzzy differential superordinations and the third-order fuzzy best subordinant, respectively. The investigation is concluded by stating sandwich-type results that connect the outcomes of the two dual theories. The approach concerns the key notion of the class of admissible functions of those theories. Research context is presented in Section 1, while the basic notions and previously established results necessary for the development of the new outcomes are contained in Section 2. Section 3 reveals the original results gathered in three subsections—third-order fuzzy differential subordination results, third-order fuzzy differential superordination results, and sandwich-type theorems connecting those results, respectively. The third-order fuzzy differential subordination outputs of this study consist of taking into consideration two classes of admissible functions, each used for proving theorems and associated corollaries that enrich the knowledge of this recently identified field of research. The fuzzy best dominant is also established for the investigated third-order fuzzy differential subordinations. The dual third-order fuzzy differential superordination outputs follow a similar pattern by taking into consideration two classes of admissible functions and using them for the establishment of theorems and associated corollaries. The fuzzy best subordinant is also established for the investigated third-order fuzzy differential superordinations. The study is concluded by stating two sandwich-type theorems that connect the outcomes of the two dual theories.
5. Conclusions
The results could inspire the use of the new operator given by Relation (5) for introducing new fuzzy classes of analytic functions as seen in the recent publications [26,27]. Also, the pattern applied here for this operator is likely to be followed using other operators for which second-order fuzzy differential subordinations and superordinations have been previously obtained, and it could be extended to fit the new context of higher-order fuzzy differential subordinations and superordinations. Such results can be cited as [28,29,30].
Author Contributions
Conceptualization, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Methodology, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Software, E.E.A. and G.I.O.; Validation, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Formal analysis, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Investigation, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Resources, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Data curation, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Writing—original draft, E.E.A. and G.I.O.; Writing—review & editing, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Visualization, E.E.A., G.I.O., R.M.E.-A. and A.M.A.; Supervision, G.I.O.; Project administration, E.E.A.; Funding acquisition, G.I.O. All authors have read and agreed to the published version of the manuscript.
Funding
The publication of this paper was funded by the University of Oradea, Romania.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.
Conflicts of Interest
The authors declare no conflicts of interest.
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