Abstract
The aim of the present paper is to introduce and study some new subclasses of p-valent functions by making use of a linear q-differential Borel operator.We also deduce some properties, such as inclusion relationships of the newly introduced classes and the integral operator .
Keywords:
p-valent; analytic function; starlike functions; convex functions; close-to-convex functions; fractional derivative; linear q-differential Borel operator MSC:
05A30; 30C45; 11B65; 47B38
1. Introduction
Let denote the class of functions of the form:
which are analytic in the open unit disc
Let be the class of functions analytic in satisfying the properties and
where and This class was introduced by (Aouf [] with ).
We note that
- (i)
- (see Padmanabhan and Parvatham []);
- (ii)
- (see Pinchuk [] and Robertson []);
- (iii)
- where is the class of functions with a positive real part greater than (see []);
- (iv)
- where is the class of functions with a positive real part (see []).
From (2), we have if and only if there exists such that
Define here a Borel distribution with parameter , which is a discrete random variable denoted by . This variable takes the values with the probabilities , respectively.
Wanas and Khuttar [] recently introduced the Borel distribution (BD) whose probability mass function is (see [,])
Wanas and Khuttar studied a series whose coefficients are probabilities of the Borel distribution (BD)
where
We propose a linear operator as follows
In a recent paper, Srivastava [] studied various types of operators regarding q-calculus. We recall further some important definitions and notations. The q-shifted factorial is defined for and as follows
By using the q-gamma function we get
where (see [])
Furthermore, we note that
and, the q-gamma function is known
where denotes the basic q-number defined as follows
Using the definition from (7), we have the next two products:
- (i)
- For a non negative integer j, the q-shifted factorial is defined by
- (ii)
- For a positive number r, the q-generalized Pochhammer symbol is given by
In terms of the classical (Euler’s) gamma function , we have
Furthermore, we notice that
2. Preliminaries
In order to establish our new results, we have to recall the construct of a q-derivative operator. Considering , the q-derivative operator [] (see also other specific and generalized results [,,,,]) for is defined by
where is defined in (7)
For and , we obtain the linear operator by
where the function is given by
A simple computation shows that
where
For with the aid of the operator one can defined the linear q-differential Borel operator as follows:
Remark 1.
By particularizing the parameters and we derive the following operators based on Borel distribution:
- (1)
- Letting we obtain that , where the operator is defined as follows:
- (2)
- Letting and we deduce that , where the operator , introduced by El-Deeb and Murugusundaramoorthy [];
- (3)
- Letting and , we deduce that where the operator is defined as follows
- (4)
- Putting and , we obtain that where the operator , studied byEl-Deeb and Murugusundaramoorthy [].
Now we introduce the following classes and of the class for and as follows:
and
Obviously, we know that
Remark 2.
By particularizing the parameter we obtain the following classes:
- (i)
- where is the well-known class of valently starlike functions of order α and was studied by Patil and Thakare [];
- (ii)
- where is the well-known class of valently convex functions of order α and was studied by Owa [];
- (iii)
- where is the class of all valently close-to-convex functions of order β and type and was introduced by Aouf [].
Next, by making use of the operator defined by (10), we obtain the following subclasses , and of the class as follows:
and
We can easily see that
In order to establish our main results, we will require the following lemmas.
Lemma 1
([,]). Let be complex valued function, is the complex plane) and let Suppose that satisfies the following conditions:
- (i)
- is continuous in a domain
- (ii)
- and
- (iii)
- for all and such that
Let be regular in Δ such that for all If
then
Lemma 2
([]). Let Φ be convex and be starlike in Δ. Then, for Υ analytic in Δ with , is contained in the convex hull of .
3. Inclusion Properties Involving the Operator
Further, we assume throughout this paper that and the power are the principal values.
Theorem 1.
For and then
where ζ is given by
Proof.
By computing the logarithmical derivative of (21) with respect to , we have
We form the function by choosing and Thus
Then, we have
- (i)
- is continuous function in
- (ii)
- and
- (iii)
for all such that
where
We note that , if and only if and From , we obtain as given by (18), and from we have By applying Lemma 1, and consequently for This completes the proof of Theorem 1. □
Theorem 2.
Proof.
Let
This completes the proof of Theorem 2. □
Theorem 3.
For and then
Proof.
Let Then, there exists such that
Then
Furthermore, and by using Theorem 1, with we have Therefore, we can write
where is analytic and in . By differentiating (24) with respect to , we have
then
Let
and
We intend to show that or for Then, we can say that From (24) and (28), we have
and this implies that
We form the function by choosing and Thus,
Then
- (i)
- is continuous in
- (ii)
- and
- (iii)
for all such that
Byapplying Lemma 1, we have for and consequently for This completes the proof of Theorem 3. □
4. Inclusion Properties Involving the Integral Operator
The generalized Bernardi operator is defined by (see [])
which satisfies the following relationship:
Theorem 4.
If and then
Proof.
By computing the logarithmical derivative of (34) with respect to and multiplying by , we have
We form the function by choosing and Thus
Clearly, conditions (i), (ii) and (iii) of Lemma 1 are satisfied. Byapplying Lemma 1, we have for and consequently for This completes the proof of Theorem 1. □
Theorem 5.
If and then
Proof.
Let
By applying Theorem 4, we have
which evidently proves Theorem 5. □
5. Inclusion Properties by Convolution
Theorem 6.
Let Φ be a convex function and then where and
Proof.
To show that it sufficient to show that contained in the convex hull of Now
where is analytic in and From Lemma 2, we can see that is contained in the convex hull of since is analytic in and
then lies in this implies that . □
Theorem 7.
Let Φ be a convex function and then where and
Proof.
Now applying (13) again, we obtain , which evidently proves Theorem 7. □
Remark 3.
Particularizing the parameters and in the results of this paper, we derive various results for different operators.
6. Conclusions
In the present survey, we propose new subclasses of p-valent functions by making use of the linear q-differential Borel operator. The applications of this interesting operator are discussed. Inclusion properties and certain integral preserving relations were aimed to be our main concern.
Author Contributions
Conceptualization, A.C. and S.M.E.-D.; methodology, S.M.E.-D.; validation, A.C., E.-R.B. and S.M.E.-D.; formal analysis, E.-R.B.; investigation, A.C., E.-R.B. and S.M.E.-D.; writing—original draft, S.M.E.-D.; writing—review & editing, A.C. and S.M.E.-D.; visualization, E.-R.B.; supervision, S.M.E.-D.; project administration, S.M.E.-D. All authors have read and agreed to the published version of the manuscript.
Funding
The research was funded by the University of Oradea, Romania.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
No data were used to support this study.
Conflicts of Interest
The authors declare no conflict of interest.
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