Abstract
In this research, we study suitable classes of admissible functions and establish the properties of third-order differential subordination by making use a certain differential operator of analytic functions in and have the normalized Taylor–Maclaurin series of the form: . Some new results on differential subordination with some corollaries are obtained. These properties and results are symmetry to the properties of the differential superordination to form the sandwich theorems.
1. Introduction
Let be the class of functions which are analytic in the open unit disk Also let be the subclass of in which the functions satisfy the following form:
Let be a subclass of which are analytic in and have the normalized Taylor-Maclaurin series of the form:
Suppose that are analytic functions in We say that is subordinate to , written as follows:
if there exists a Schwarz function which is analytic in with such that
Furthermore, if is univalent in we have [1]:
For a function given by (1) and defined by:
the Hadamard product (or convolution) of denoted by is defined by
We’ll go over some additional terms and concepts from the differential subordination theory here.
Definition 1.
[2] Let and suppose that the function is univalent in If the function is analytic in and satisfies the following third-order differential subordination:
then is called a solution of the differential subordination . Furthermore, a given univalent function is called a dominant of the solutions of or more simply, a dominant if for all satisfying (4). A dominant that satisfies for all dominants of (4) is said to be the best dominant.
Definition 2.
[2] Let be the set of all functions that are analytic and univalent on where
and . Further, let the subclass of for which be denoted by with
The subordination methodology is applied to appropriate classes of admissible functions.
The following class of admissible functions was given by Antonino and Miller [2].
Definition 3.
[2] Let be a set in . Also and . The class of admissible functions consists of those functions which satisfy the following admissibility conditions:
whenever
and
where
Lemma 1.
[2]: Let satisfying the following conditions:
where If is a set in and
then
The geometric function theory relies heavily on the study of operators. Convolution of certain analytic functions may be used to express several differential and integral operators. This formalism, it is noticed, facilitates further mathematical research and also aids in a better understanding of the geometric aspects of such operators. The importance of convolution in the theory of operators may be understood by the following set of examples given by Barnard and Kellogg [3] and Carlson–Shaffer [4], etc.
Now, we introduce new operator by using the convolution in our this study.
Definition 4.
Letwe define the operator:
by
where
Let Then
In general
By simple calculation, we obtain
The notion of the third-order differential subordination can be found in the work of Ponnusamy and Juneja [5]. The recent work by several authors (see for example, [6,7]; see also [8,9]) on the differential subordination attracted many researchers in this field. For example, see [8,10,11,12,13,14,15,16,17,18,19,20].
In this research, we investigate suitable classes of admissible functions associated with the new differential operator and establish the properties of third-order differential subordination by making use a certain new differential operator of analytic functions in and have the normalized Taylor–Maclaurin series of the form: . Some new results on differential subordinations with some corollaries are obtained. Here, we obtain the symmetry of the differential superordination results.
2. Results Related to the Third-Order Differential Subordination
We start with a given set and a function in this section, and we establish a set of acceptable functions so that (4) holds true. We construct the following new class of admissible functions for this purpose, which will be needed to establish the key third-order differential subordination theorems for the operator described by (7).
Definition 5.
Letbe a set inThe classof admissible functions consists of those functionsthat satisfy the following admissibility conditions:
whenever
and
where
Theorem 1.
Let. If the functions, satisfy the following conditions:
and
then
Proof.
Define the analytic function by
Form Equations (8)–(11), we have
By a similar argument, we get
and
Define the transformation from by
Let
Using the Equations (11)–(14), and from the Equation (17), we have
Hence, clearly (10) becomes
we note that
and
Thus clearly, the admissibility condition for in Definition 4, is equivalent to admissibility condition as given in Definition 3 with
Therefore, by using (9) and Lemma 1, we have
This completes the proof. □
Our next result is consequence of Theorem 1, when the behavior of on is not known.
Corollary 1.
Letand let the functionbe univalent inLetwhereIf the functionandsatisfies the following conditions:
and
then
Proof.
By applying Theorem 1, we get
The result asserted by Corollary 1 is now deduced from following subordination property
This completes the proof of Corollary 1. □
If is a simply connected domain, the on to In this case the class is written as . This leads to the following immediate consequence of Theorem 1.
Theorem 2.
LetIf the functionsatisfy the following conditions:
and
then
The next result is an immediate consequence of Corollary 1.
Corollary 2.
Letand let the functionbe univalent inAlso letwhereIf the functionandsatisfies the following conditions:
and
then
The following result yield the best dominant of differential subordination (20).
Theorem 3.
Let the functionbe univalent inAlso letandgiven by (17). Suppose that following differential equation
then
andis the best dominant.
Proof from Theorem 1.
We see that is a dominant of (19) since satisfies (20), it is also a solution of (19). Therefore, will be dominated by all dominants. Hence, is the best dominant. This completes the proof of Theorem 3. □
In view of Definition 5, and in special case when the class of admissible functions, denoted by is expressed follows.
Definition 6.
Letbe set inandThe classof admissible functions consists of those functionssuch that
where
and
Corollary 3.
LetIf the functionsatisfies the following conditions
and
then
In special case, when the class is simple denoted by Corollary 3 can now be rewritten in the following from.
Corollary 4.
LetIf the functionsatisfies the following conditions
and
then
Corollary 5.
LetIf the functionsatisfies the following conditions:
and
then
Proof.
Let where
use Corollary 3, we need to show that that is the admissibility condition (22), is satisfied. This follows readily, since it is seen that
where The required result now follows from Corollary 3. This completes the proof. □
Definition 7.
Letbe a set inthe classof admissible functions consists of those functionssatisfy the following admissibility conditions
whenever
and
where
Theorem 4.
LetIf the functionsatisfy the following conditions:
and
then
Proof.
Define by
from Equations (8) and (11), we have
By a similar argument, we get
and
Define the transformation from by
and
Let
The proof will make use of lemma 1. Using the Equations (25)–(27) and from the Equation (31), we have
Hence, clearly (24) becomes
We note that
and
Thus, clearly, the admissibility condition for in definition 7 is equivalent to admissibility condition for as given in Definition 3 with
Therefore, by using (23) and Lemma 1, we have
□
If is a simply connected domain, the on to In this case the class is written as . This leads to the following immediate consequence of Theorem 4 is stated below.
Theorem 5.
LetIfsatisfy the following conditions:
and
then
In view of Definition 7, and in special case when the class of admissible functions, denoted by is expressed follows.
Definition 8.
Letbe set inThe classof admissible functions consists of those functionsuch that
whenever,
and
Corollary 6.
LetIf the functionsatisfies the following conditions
and
then
When the class is simple denoted by Corollary 6 can now be rewritten in the following from.
Corollary 7.
LetIf the functionsatisfies the following conditions
and
then
Definition 9.
Letbe a set inthe classof admissible functions consists of those functionssatisfy the following admissibility conditions
whenever
and
where
Theorem 6.
LetIf the functionsatisfy the following conditions:
and
then
Proof.
Define the analytic function by
From Equations (8) and (38), we have
By a similar argument, we get
and
where
and
We now define the transformation from
and
where
and
Let
The proof will make use of lemma 1. Using the Equations (38)–(41), and from the Equation (44), we have
Hence, clearly (37) becomes
We note that
and
Thus clearly, the admissibility condition for in Definition 9 is equivalent to admissibility condition for , as given in Definition 3 with
Therefore, by using (36) and Lemma 1, we have
This completes the Proof of Theorem 6. □
If is simply-connected domain, then on to In this case, the class is written as . An immediate consequence of Theorem (4) is now stated below without proof.
Theorem 7.
LetIfsatisfy the following conditions (37) and
then
3. Discussion
We study classes of admissible functions and establish the properties of third-order differential subordination using certain differential operator of analytic functions in and have the normalized Taylor–Maclaurin series of the form: . Some new results on differential subordination with some corollaries are obtained. These properties and results are symmetry to the properties of the differential superordination to form the sandwich theorems. Our results are different from the previous results for the other authors. We opened some windows for authors to generalize our new subclasses to obtain some new results in univalent and multivalent function theory using the results in the paper.
Author Contributions
Conceptualization, methodology, software by A.A.L., validation, formal analysis, investigation, resources, by A.H.B., data curation, writing—original draft preparation, writing—review and editing, visualization by W.G.A., supervision, project administration, funding acquisition, by A.M.D. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
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.
References
- Miller, S.S.; Mocanu, P.T. Differential Subordinations: Theory and Applications. In Series on Monographs and Textbooks in Pure and Applied Mathematics; No 225, Marcel Dekker Incorporated: Abington, UK, 2000. [Google Scholar]
- Antonino, J.A.; Miller, S.S. Third-order differential inequalities and subordinations in the complex plane. Complex Var. Elliptic Equ. 2011, 56, 439–454. [Google Scholar] [CrossRef]
- Barnard, R.W.; Kellogg, C. Applications of convolution operators to problems in univalent function theory. Mich. Math. J. 1980, 27, 81–94. [Google Scholar] [CrossRef]
- Carlson, B.C.; Shaffer, D.B. Starlike and Prestarlike Hypergeometric Functions. SIAM J. Math. Anal. 1984, 15, 737–745. [Google Scholar] [CrossRef]
- Ponnusamy, S.; Juneja, O.P. Third-Order Differential Inqualities in the Complex Plane. In Current Topics in Analytic Function Theory; World Scientific Publishing Company: Singapore, 1992. [Google Scholar]
- Farzana, H.A.; Stephen, B.A.; Jeyaraman, M.P. Third Order Differential Subordination of Analytic Function Defined by Fractional Derivative Operator. Ann. Alexandru Ioan Cuza Univ.-Math. 2014, I, 105–120. [Google Scholar] [CrossRef] [Green Version]
- Atshan, W.G.; Battor, A.H.; Abaas, A.F. On Third-Order Differential Subordination Results for Univalent Analytic Functions Involving an Operator. J. Phys. Conf. Ser. 2020, 1664, 1–19. [Google Scholar] [CrossRef]
- Tang, H.; Deniz, E. Third-order differential subordination results for analytic functions involving the generalized Bessel functions. Acta Math. Sci. 2014, 34, 1707–1719. [Google Scholar] [CrossRef]
- Tang, H.; Srivastava, H.M.; Li, S.-H.; Ma, L. Third-Order Differential Subordination and Superordination Results for Meromorphically Multivalent Functions Associated with the Liu-Srivastava Operator. Abstr. Appl. Anal. 2014, 2014, 1–11. [Google Scholar] [CrossRef]
- Al-Ameedee, S.A.; Atshan, W.G.; Al-Maamori, F.A. On sandwich results of univalent functions defined by a linear operator. J. Interdiscip. Math. 2020, 23, 803–809. [Google Scholar] [CrossRef]
- Cotirlă, L. A differential sandwich theorem for analytic functions defined by the integral operator. Studia Univ. Babes-Bolyai Math. 2009, 54, 13–21. [Google Scholar]
- Atshan, W.G.; Ali, A.A.R. On Sandwich Theorems Results for Certain Univalent Functions Defined by Generalized Operators. Iraqi J. Sci. 2021, 62, 2376–2383. [Google Scholar] [CrossRef]
- Atshan, W.G.; Battor, A.H.; Abaas, A.F. Some sandwich theorems for meromorphic univalent functions defined by new integral operator. J. Interdiscip. Math. 2021, 24, 579–591. [Google Scholar] [CrossRef]
- Atshan, W.G.; Hadi, R.A. Some Differential Subordination and Superordination Results of p-valent Functions Defined by Differential Operator. J. Phys. Conf. Ser. 2020, 1664, 1–15. [Google Scholar] [CrossRef]
- Gochhayat, P.; Prajapati, A. Applications of third order diferential subordination and superordination involving generalized Struve function. arXiv 2019, arXiv:1809.06512. [Google Scholar]
- Cho, N.E.; Bulboacă, T.; Srivastava, H.M. A General family of integral operators and associated subordination and superordination properties of some special analytic function classes. Appl. Math. Comput. 2012, 219, 2278–2288. [Google Scholar] [CrossRef]
- Jeyaraman, M.P.; Suresh, T.K. Third-order differential subordination of analytic function. Acta Univ. Apulensis 2013, 35, 187–202. [Google Scholar]
- Murugusundaramoorthy, G.; Magesh, N. An application of second order differential inequalities based on linear and integral operators. Int. J. Math. Sci. Eng. Appl. 2008, 2, 105–114. [Google Scholar]
- Răducanu, D. Third-Order Differential Subordinations for Analytic Functions Associated with Generalized Mittag-Leffler Functions. Mediterr. J. Math. 2017, 14, 167. [Google Scholar] [CrossRef]
- Tang, H.; Srivastava, H.M.; Deniz, E.; Li, S.-H. Third-Order Differential Superordination Involving the Generalized Bessel Functions. Bull. Malays. Math. Sci. Soc. 2014, 38, 1669–1688. [Google Scholar] [CrossRef]
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