1. Introduction
The convexity of a function has played a very important role as a tool in the development of inequalities. The relationship of this concept is always present in branches such as functional analysis [
1], harmonic analysis (specifically in interpolation theory) [
2] and control theory and optimization [
3]. This property is defined by Jensen in [
4,
5] as follows.
Definition 1. A function is said to be convex on if:holds for every and The famous Hermite–Hadamard inequality, which involves convex functions, appears in the literature regarding the study of inequalities. Its name was derived from the works of Hermite, Ch. [
6] and Hadamard J. [
7], and it was established as follows.
Theorem 1. Let be a convex function on I and with Then the following inequality holds: Inequality (1) is also known as trapezium inequality. The trapezium-type inequality has remained a subject of great interest due to its broad application in the field of mathematical analysis. For other recent results which generalize, improve and extend inequality (
1) through various classes of convex functions, interested readers may consult [
8,
9,
10,
11,
12,
13].
Quantum calculus, also known as calculus with no limits, was begun by Euler in the eighteenth century (1707–1783). In 1910, Jackson F.H. [
14] began a symmetric study of q-calculus and introduced q-definite integrals. He was also the first to develop q-calculus in a systematic fashion. Some branches of mathematics and physics, such as number theory, orthogonal polynomials, combinatorics, basic hypergeometric functions, quantum theory, mechanics and the theory of relativity, have been enriched by the research work of various authors such as Ernst T. [
15], Gauchman H. [
16] and Kac V. [
17].
Motivated by the growing body of work on the development of the concept of convexity, its relationships with integral inequalities and its connection with quantum analysis, as is addressed in the work mentioned above, in this work we seek to establish certain quantum estimates of trapezium-type inequalities for generalized -convex functions.
2. Preliminaries
Let K be a non-empty closed set in and a continuous function.
In [
10], Noor M.A. introduced a new class of non-convex functions, the so-called
-convex, as follows:
Definition 2. The function on the ϕ-convex set K is said to be ϕ-convex, if: The function f is said to be -concave if is -convex. Note that every convex function is -convex but in general the converse does not hold.
In [
18], Raina R.K. introduced a class of functions defined by:
where
and:
is a bounded sequence of positive real numbers. Note that, if we take in (
2)
and:
where
and
are parameters which can take arbitrary real or complex values (provided that
and the symbol
denotes the quantity:
and restrict its domain to
(with
), then we have the classical hypergeometric function, which is:
In addition, if
with
and restricting its domain to
in Equation (
2), then we have the classical Mittag-Leffler function:
Finally, let us recall the new class of set and new class of functions involving Raina’s function introduced by Vivas-Cortez et al. in [
13], the so-called generalized
-convex set as well as the generalized
-convex function.
Definition 3. Let and be a bounded sequence of positive real numbers. A non-empty set K is said to be a generalized ϕ-convex set, if:where is Raina’s function. Definition 4. Let and be a bounded sequence of positive real numbers. If a function satisfies the following inequality:for all and then f is called generalized ϕ-convex. Remark 1. Taking in Definition 4, we then obtain Definition 1. Moreover, under suitable choices of we get Definition 2.
Recently, several authors have utilized quantum calculus as a strong tool in establishing new extensions of trapezium-type and other inequalities, see [
17,
19,
20,
21,
22,
23,
24] and the references therein.
We now recall some concepts from quantum calculus. Let be an interval and be a constant.
Definition 5 ([
23]).
Let be a continuous function and Then q-derivative of f on I at x is defined as:We say that f is q-differentiable on I provided exists for all Note that if in Equation (5), then where is the well-known q-derivative of the function defined by: Definition 6 ([
23]).
Let be a continuous function. Then the second-order q-derivative of f on which is denoted as provided is q-differentiable on I with Definition 7 ([
23]).
Let be a continuous function. Then the q-integral on I is defined by: for Note that if then we have the classical q-integral, which is defined by: for Theorem 2 ([
23]).
Assume that are continuous functions, Then, for we have: Definition 8 ([
17]).
For any real number is called the q-analogue of . If we denote: Definition 9 ([
17]).
If the q-analogue of is the polynomial: Definition 10 ([
17]).
For any is called the q-Beta function. Note that: where is the q-analogue of Finally, from [
24], four simple lemmas will be used in this paper.
Lemma 1. Let then we have: Lemma 2. Let then we have: Lemma 3. Let where is a constant, then we have: Lemma 4. Let where is a constant, then we have: Liu et al. in [
20] established the following
q-integral identity.
Lemma 5. Let be a twice q-differentiable function on with being continuous and integrable on where Then the following identity holds: Motivated by the aforementioned literature, this paper is organized as follows: In
Section 3, a quantum trapezium-type inequality using a new class of functions, the so-called generalized
-convex, will be represented. A quantum trapezium-type inequality for the product of two generalized
-convex functions will also be provided. In
Section 4, an identity for a twice
q-differentiable functions involving Raina’s function will be established. Applying these identities, we develop some quantum estimate inequalities for the above class of functions. Various special cases will be obtained. In
Section 5, a brief conclusion is given.
3. Quantum Trapezium-Type Inequalities
Throughout this paper the following notations are used:
where
and
are bounded sequence of positive real numbers. Moreover, for convenience we denote
for
where
In this section, we first establish quantum estimates for trapezium-type inequalities via generalized -convexity.
Theorem 3. Let be a generalized ϕ-convex function on (the interior of O) such that Then the following double inequality holds: Proof. Let
and
Then:
Since
f is a generalized
-convex function, we have:
and:
Taking the
q-integral of both sides in Equation (
7) with respect to ı on
we get:
Changing the variables of integration in Equation (
8), we obtain the left-side inequality of Equation (
6). To prove the right-side inequality of Equation (
6), from generalized
-convexity of
we have:
Changing the variables of integration, we obtain the right-side inequality of Equation (
6). The proof of Theorem 3 is completed. □
Corollary 1. In Theorem 3, taking we get the following new double inequality: Remark 2. In Corollary 1, taking we recapture Theorem 1.
We are now in a position to derive a new quantum trapezium-type inequality for the product of two generalized -convex functions.
Theorem 4. Let be two generalized ϕ-convex functions on (the interior of O) such that Then the following double inequality holds:where:and: Proof. Let
and
Then:
and:
Since
f and
g are generalized
-convex functions, we have:
and:
Multiplying the above inequalities, we have:
Taking the
q-integral of both sides in Equation (
12) with respect to ı on
and changing the variables of integration, we get:
By using Lemmas 1–4, the left-side inequality of Equation (11) is proved. To prove the right-side inequality of Equation (11), from the generalized
-convexity of
f and
we have:
The right-side inequality of Equation (11) is thus proved. The proof of Theorem 4 is completed. □
Corollary 2. In Theorem 4, taking we get the following new double inequality: Corollary 3. In Corollary 2, taking we get: Corollary 4. In Theorem 4, taking we get: 4. Other Quantum Inequalities
In this section, we first derive a new quantum integral identity for twice q-differentiable functions involving Raina’s function.
Lemma 6. Let be a twice q-differentiable function on with being continuous and integrable on Then the following identity holds:where: Proof. Using Definitions 5–7, we have:
Multiplying both sides of the above equality: by we get the desired result. The proof of Lemma 6 is completed. □
Remark 3. Taking in Lemma 6, we obtain the following new identity:where: Remark 4. Taking in Lemma 6, we get Lemma 5.
Now, applying Lemma 6, we establish some quantum estimate inequalities for the generalized -convex function.
Theorem 5. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on then the following inequality holds:where: Proof. Using Lemmas 1–4 and Lemma 6 and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 5 is completed. □
Corollary 5. Taking in Theorem 5, we get: Corollary 6. Taking in Theorem 5, we get: Theorem 6. Let be a twice q-differentiable function on with being continuous and integrable on If is a generalized ϕ-convex on for and then the following inequality holds:where: Proof. Using Lemmas 1–4 and Lemma 6, Hölder’s inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 6 is completed. □
Corollary 7. Taking in Theorem 6, we get: Corollary 8. Taking in Theorem 6, we get: Theorem 7. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on then for the following inequality holds:where is defined from Theorem 4 and is defined from Theorem 5. Proof. Using Lemmas 1–4 and Lemma 6, the well-known power mean inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 7 is completed. □
Corollary 9. Taking in Theorem 7, we get Theorem 5.
Corollary 10. Taking in Theorem 7, we get: Corollary 11. Taking in Theorem 7, we get: Theorem 8. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on for and then the following inequality holds:where:and is defined from Theorem 4. Proof. Using Lemmas 1–4 and Lemma 6, Hölder’s inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 8 is completed. □
Corollary 12. Taking in Theorem 8, we get: Corollary 13. Taking in Theorem 8, we get: Theorem 9. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on then for the following inequality holds:where:and is the q-analogue of Proof. Using Lemmas 1–4 and Lemma 6, the well-known power mean inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 9 is completed. □
Corollary 14. Taking in Theorem 9, we get:where: Corollary 15. Taking in Theorem 9, we get: Theorem 10. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on for and then the following inequality holds:where is defined from Theorem 4 and is a q-Beta function. Proof. Using Lemmas 1–4 and Lemma 6, Hölder’s inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 10 is completed. □
Corollary 16. Taking in Theorem 10, we get: Corollary 17. Taking in Theorem 10, we get: Theorem 11. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on then for the following inequality holds:where is defined from Theorem 8, for Proof. Using Lemmas 1–4 and Lemma 6, the well-known power mean inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 11 is completed. □
Corollary 18. Taking in Theorem 11, we get: Corollary 19. Taking in Theorem 11, we get: Theorem 12. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on for and then the following inequality holds:where is the q-analogue of and is defined from Theorem 8, for Proof. Using Lemmas 1–4 and Lemma 6, Hölder’s inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 12 is completed. □
Corollary 20. Taking in Theorem 12, we get: Corollary 21. Taking in Theorem 12, we get: Theorem 13. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on for and then the following inequality holds:where is the q-analogue of r and is defined from Theorem 12, for Proof. Using Lemmas 1–4 and Lemma 6, Hölder’s inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 13 is completed. □
Corollary 22. Taking in Theorem 13, we get: Corollary 23. Taking in Theorem 13, we get: Theorem 14. Let be a twice q-differentiable function on with being continuous and integrable on If is generalized ϕ-convex on then for the following inequality holds:where: Proof. Using Lemmas 1–4 and Lemma 6, the well-known power mean inequality and the fact that
is a generalized
-convex function, we have:
The proof of Theorem 14 is completed. □
Corollary 24. Taking in Theorem 14, we get: Remark 5. For different choices of where are bounded sequence of positive real numbers in Raina’s function, we can arrive at new fascinating inequalities. Moreover, our results can be applied to derive some inequalities using special means. For example, from Corollary 5 taking , and recalling the well known means:
- 1.
- 2.
Generalized Logarithmic:we have the following inequality:
The details are left to the interested reader.
5. Conclusions
Since quantum calculus is broadly applicable in many mathematical areas, this new class of functions, the so-called generalized -convex, can be applied to obtain various results in convex analyses, special functions, quantum mechanics, related optimization theories and mathematical inequalities and it may stimulate further research in different areas of pure and applied sciences.