Abstract
Integral operators with the Mittag–Leffler function in kernels play a very vital role in generalizing classical integral inequalities. This paper aims to derive Ostrowski-type inequalities for k-fractional integrals containing Mittag–Leffler functions. Several new inequalities can be deduced for various fractional integrals in particular cases. Applications of these inequalities are also given.
MSC:
26A51; 26A33; 33E12
1. Introduction
In [1], Ostrowski proved the following inequality, which is well known as the Ostrowski inequality.
Theorem 1.
Let be a differentiable mapping in , the interior of I, and , . If for all , then for , the following inequality holds:
The inequality (1) provides the boundedness of the difference between the value of at an arbitrary point of and its integral mean, , provided that the derivative is bounded. From the point of view of applications, this inequality gives the error bounds of the midpoint and trapezoidal numerical quadrature rules, and its applications to special means can be found; see [2,3].
In the last few years, several authors have studied classical inequalities for various types of fractional integrals by using different kinds of convex functions. For example, Set [4] and Liu [5] proved the Ostrowski-type inequalities for Riemann–Liouville fractional integrals via s-convex and h-convex functions. Kermausuor [6] and Lakhal [7] gave the Ostrowski-type inequalities for Riemann–Liouville k-fractional integrals via strongly -convex functions and -convex functions. In [8], Set et al. proved the Ostrowski-type inequalities for conformable fractional integrals via convex and AG-convex functions. In [9], Gürbüz et al. gave the Ostrowski-type inequalities for Katugampola fractional integrals via p-convex functions. In [10], Basci and Baleanu derived the Ostrowski-type inequalities for -Hilfer fractional integrals. In [11], Faisal et al. established the Hermite–Hadamard–Jensen–Mercer fractional inequalities for convex functions, and similar inequalities for -type real-valued convex functions were also given in [12]. In [13], Farid et al. derived the Ostrowski-type inequalities for fractional integrals containing an extended generalized Mittag–Leffler function.
Inspired by the above research, our aim in this paper is to derive the Ostrowski-type inequalities for the generalized k-fractional integrals given in Definition 3 that contain the Mittag–Leffler function (8). One can deduce several new and existing Ostrowski-type inequalities. Some applications of the established inequalities are discussed in the penultimate section of this paper.
The Mittag–Leffler function plays an important role in solving fractional differential equations. It is also used in the generalization of fractional integrals. In the literature, several inequalities have been established for various fractional integrals containing the Mittag–Leffler function. The Mittag–Leffler function has been generalized by many authors: For example, Wiman [14], Prabhakar [15], Shukla and Prajapati [16], Salim and Faraj [17], and Rahman et al. [18] have contributed significantly to its generalizations and extensions. Recently, Andrić et al. [19] defined the extended generalized Mittag–Leffler function as follows.
Definition 1.
Let , , with , , and . Then,
where is the generalized beta function and is the Pochhammer symbol .
One can see that and that is symmetric with respect to its arguments. Symmetry is an important property; things that have this property look more beautiful and fascinating. Likewise, symmetric functions play a very vital role in the theory of mathematical inequalities. Many classical inequalities for symmetric functions have been studied. For example, real functions that are defined on and are symmetric about satisfy the following generalization of the Hadamard inequality.
Theorem 2.
Let be a convex function defined on an interval and , where . If is a symmetric function about , then the following inequality holds:
A version of the Hadamard inequality for convex and symmetric functions about via Riemann–Liouville fractional integrals was given in [20]. Next, we define generalized fractional integrals as follows.
Definition 2 ([19]).
Let , , be an integrable function. In addition, let , , and with , , and . Then, for , the generalized fractional integrals are defined by:
Zhang et al. [21] introduced the generalized k-fractional integrals involving the Mittag–Leffler function as follows:
Definition 3.
where is the modified Mittag–Leffler function defined by:
Let , , be two functions, such that is positive and , and is differentiable and strictly increasing. In addition, let , , with , , , and . Then, for , the generalized k-fractional integrals are defined by:
Remark 1.
For a constant function, Zhang et al. [21] proved the following:
and
We have organized this paper as follows: In the upcoming section, we first establish an identity in order to derive Ostrowski-type inequalities. Then, by applying this identity and k-fractional integrals (6) and (7), Ostrowski-type inequalities are established. It is mentioned that several new Ostrowski-type inequalities can be deduced for the well-known fractional integrals compiled in [21] (Remarks 1 and 2). In the last section, some applications of the presented results are given.
2. Main Results
First, we establish the following lemma for the modified Mittag–Leffler function.
Lemma 1.
If , , with , , , and , then
Proof.
We have
After simple computation, the identity (11) is achieved. □
Next, we give the generalized k-fractional Ostrowski-type inequality containing the modified Mittag–Leffler function.
Theorem 3.
Proof.
Let and . Then, for the monotonically increasing function and the Mittag–Leffler function (8), we can write:
First, we consider the inequality (15) as follows:
Similarly, by using the same technique, from (16), one can achieve the following inequality:
Now, on the other hand, let and . Then, for the monotonically increasing function and the Mittag–Leffler function (8), we can write:
Corollary 1.
For in (13), the following inequality holds:
Remark 2.
In Theorem 3, for , we attain Theorem 2 from [22]. For , we attain Theorem 7 from [23]. For and , we attain Theorem 2.1 from [13]. For and , we attain Theorem 1.2 from [24].
The next result is a general form of a generalized k-fractional Ostrowski inequality containing the modified Mittag–Leffler function (8).
Theorem 4.
Let be a differentiable mapping in , the interior of I, and , . In addition, let be an increasing and differentiable function with . If is integrable and for all , then for , the following inequalities for fractional integrals (6) and (7) hold:
and
Proof.
From inequalities (28) and (29), after simple computation, one can achieve the following inequalities:
and
Now, on the other hand, from the boundedness condition of and (21), we have the following inequalities:
and
Theorem 5.
Under the assumptions of Theorem 4, the following inequalities hold:
and
Proof.
Theorem 6.
Under the assumptions of Theorem 3, the following inequality holds:
Proof.
Let and . Then, for the monotonically increasing function and the Mittag–Leffler function (8), we can write:
First, we consider the inequality (40) as follows:
The inequality (42) takes the following form after integrating by parts and using Lemma 1:
Similarly, by using the same technique as that from (41), one can achieve
Now, on the other hand, let and . Then, for the monotonically increasing function and the Mittag–Leffler function (8), we can write:
Some direct consequences are given below.
Corollary 2.
For in (38), the following inequality holds:
Remark 3.
In Theorem 6, for , we attain Theorem 4 from [22]. For , we attain Theorem 9 from [23]. For and , we attain Theorem 2.6 from [13]. For and , we attain Theorem 1.4 from [24].
3. Applications
In this section, we give applications of Theorem 6. By applying Theorem 6 at the endpoints of the interval and adding the resulting inequalities, one can achieve the following results.
Theorem 7.
Under the assumptions of Theorem 6, the following inequality holds:
Corollary 3.
For in (51), the following error bounds of the Hadamard-type inequality hold:
By applying Theorem 6 at the midpoint of the interval , one can achieve the following result.
Theorem 8.
Under the assumptions of Theorem 6, the following inequality holds:
Example 1.
Let , , and , . Then, we have , , and , where and are k-analogs of the left and right Riemann–Liouville fractional integrals. Hence, the inequality (52) takes the following form:
4. Conclusions
Ostrowski-type inequalities for generalized k-fractional integrals containing the modified Mittag–Leffler function (8) were established. The outcomes of this paper include many new and existing Ostrowski-type inequalities for various types of fractional integrals. Some results are mentioned in the form of corollaries and remarks. An example is also provided.
Author Contributions
Conceptualization, D.C., S.M., G.F. and K.N.; investigation, S.M. and G.F.; methodology, D.C., G.F. and K.N.; writing—original draft, S.M. and G.F.; writing—review and editing, D.C., S.M., G.F. and K.N. 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.
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