Some Midpoint Inequalities for η-Convex Function via Weighted Fractional Integrals
Abstract
In this research, by using a weighted fractional integral, we establish a midpoint version of Hermite-Hadamrad Fejér type inequality for η-convex function on a specific interval. To confirm the validity, we considered some special cases of our results and relate them with already existing results. It can be observed that several existing results are special cases of our presented results.
1. Introduction
In the last few decades, the classical convexity has a rapid development in fractional calculus [1]. We can say that convexity plays a vital role in fractional integral inequalities because of its geometric features [2–4].
∀m, n ∈ I, and t ∈ [0, 1].
In the literature, we can notice that Hermite-Hadamarad inequality (2) has been applied to distinct convexities like exponential convexity [6, 7], s-convexity [8], quasiconvexity [9, 10], GA-convexity [11], (α, m)-convexity [12], MT-convexity [13], and also, other types of convexity (see [14, 15]). Different forms of fractional integrals like Riemann-Liouville (RL), Caputo Fabrizio, Hadamrad, Riesz, Prabhakar, Ψ-RL, and weighted integrals [16–20] have been established. A lot of integer-order integral inequalities like Simpson [21], Ostrowski [22], Rozanova [23], Gagliardo-Nirenberg [24], Olsen [25], Hardy [26], Opial [27, 28], and Akdemir et al. [29, 30] have been developed and generalized from fractional point of view.
Definition 1. Let I ⊂ ℝ be an interval and f : I⟶ℝ be a continuous function. Then, the function f is called η-convex if
Definition 2. [18] Let f is positive convex function, continuous on closed interval [m, n] and x ∈ [m, n] when f(x) ∈ L1[m, n] with m < n, where left- and right-side RL fractional integrals are defined by
Definition 3 (see [19].)Let [m, n]⊆ℝ, f : [m, n]⟶ℝ and ϕ : (m, n]⟶ℝ be monotonically increasing positive function with a continuous derivative ϕ′(x) on (m, n). Then, the left-sided and the right-sided weighted fractional integrals of f according to ϕ on [m, n] are defined by:
In this research, we denote [g(x)]−1 = 1/g(x) and the inverse of function ϕ(x) by ϕ−1(x).
Remark 4. From Definition 3, we can see some special cases:
Lemma 5. [31] Assume that g : [m, n]⟶(0, ∞) is integrable function and symmetric with respect to (m + n)/2, m < n. Then,
- (i)
For each t ∈ [0, 1], we have
(7) - (ii)
For v > 0, we have
(8)
2. Main Results
Theorem 6. Let 0 ≤ m < n and f : [m, n]⟶ℝ be an L1η-convex function and g : [m, n]⟶ℝ be an integrable, positive and weighted symmetric function with respect to (m + n)/2. If, in addition, ϕ is an increasing and positive function from [m, n] onto itself such that its derivative ϕ′(x) is continues on (m, n), then for v > 0, the following inequalities are valid:
Proof. The η-convexity of f on [m, n], for all x, y∈[m, n] gives
Multiplying both sides of inequality (11) by tv−1g((t/2)m + ((2 − t)/2)n) and integrating over [0, 1], we get
From the left side of inequality (12), we use
By evaluating the weighted fractional operators, we see that
Setting u1 = 2(n − ϕ(x))/(n − m) and u2 = 2(ϕ(x) − m)/(n − m), one can deduce that
By using (14) and (18) in (12), we get
The left side of Theorem 6 is completed.
Now, we will prove right side of inequality (9) by using η-convexity.
Multiply Equation (20) by tv−1g((t/2)m + ((2 − t)/2)n) and integrate over [0, 1] leads us to
By using (7) and (14) in (21), we get
This completes our proof.
Remark 7. From Theorem 6, we can get following special case:
If ϕ(x) = x, then inequality (9) becomes
Lemma 8. [31] Let 0 ≤ m < n and f : [m, n]⟶ℝ be a continuous with a derivative f′∈L1[m, n] such that and let g : [m, n]⟶ℝ be an integrable, positive, and weighted symmetric function with respect to (m + n)/2. If ϕ is a continuous increasing mapping form the interval [m, n] onto itself with a derivative ϕ′(x) which is continuous on (m, n), then for v > 0, the following equality is valid:
Remark 9. From Lemma 8, we obtain the following special case:
If ϕ(x) = x, then equality (24) becomes
Theorem 10. Let 0 ≤ m < n and f : [m, n]⊆[0, ∞)⟶ℝ be a differentiable function on the interval [m, n] such that and let g : [m, n]⟶ℝ be an integrable, positive, and weighted symmetric function with respect to (m + n)/2. If, in addition, |f′| is convex on [m, n], and ϕ is an increasing and positive function from [m, n) onto itself such that its derivative ϕ′(x) is continuous on (m, n), then for v > 0, the following inequalities hold:
Proof. By using Lemma 8 and properties of modulus, we get
Since |f′| is η-convex on [m, n] for t ∈ [ϕ−1(m), ϕ−1(n)], so
So, using (28), we obtain
This completes our proof.
Remark 11. From Theorem 10, we can get following inequalities:
Theorem 12. Let 0 ≤ m ≤ n and f : [m, n]⊆[0, ∞)⟶ℝ be a continuously differentiable function on the interval [m, n] such that , and let g : [m, m]⟶ℝ be integrable, positive, and weighted symmetric function with respect to (m + n)/2. If, in addition, is convex on [m, n], q ≤ 1, and ϕ is increasing and positive function from [m, n] onto itself such that its derivative ϕ′(x) is continuous on [m, m], then for v > 0, we have:
Proof. Since is η-convex on [m, n] for t ∈ [ϕ−1(m), ϕ−1(n)], so
By using power mean integral, Lemma 8, and η-convexity of , we have
Remark 13. From Theorem 12, we can get following special cases:
Theorem 14. Let 0 ≤ m ≤ n and f : [m, n]⊆[0, ∞)⟶ℝ be a continuously differentiable function on the interval [m, n] such that , and let g : [m, m]⟶ℝ be integrable, positive and weighted symmetric function with respect to (m + n)/2. If, in addition, is convex on [m, n], q ≤ 1, and ϕ is increasing and positive function from [m, n] onto itself such that its derivative ϕ′(x) is continuous on [m, m], then for v > 0, we have
Proof. Since is η-convex on [m, n], for t ∈ [ϕ−1(m), ϕ−1(n)], we get
By using Hölder’s inequality, Lemma 8, η-convexity of , and properties of modulus, we get
This completes the proof.
3. Conclusion
In this paper, we established Hermite-Hadamarad Fejér type inequalities for η-convex function by using weighted fractional integrals. Our results are extensions and generalizations of many existing results in the literature.
Conflicts of Interest
The authors of this paper declare that they have no competing interests.
Authors’ Contributions
Lei Chen analyzed the results, Waqas Nazeer proposed the problem, Farman Ali wrote the final version of the paper, Thongchai Botmart verified the results and arranged funding for this paper, and Sarah Mehfooz wrote the first version of the paper. Lei Chen and Farman Ali contributed equally to this work and are first co-authors.
Open Research
Data Availability
All data required for this research is included within the paper.