Abstract
In this article, we prove several new fractional nabla Bennett–Leindler dynamic inequalities with the help of a simple consequence of Keller’s chain rule, integration by parts, mean inequalities and Hölder’s inequality for the nabla fractional derivative on time scales. As a result of this, some new classical inequalities are obtained as special cases, and we extended our inequalities to discrete and continuous calculus. In addition, when , we shall obtain some well-known dynamic inequalities as special instances from our results. Symmetrical properties are critical in determining the best ways to solve inequalities.
Keywords:
nabla derivative; Hardy’s inequality; Hölder’s inequality; time scales; conformable fractional calculus MSC:
26A15; 26D10; 26D15
1. Introduction
In [1], Hardy presented the discrete version
where is a nonnegative real sequence.
In [2], Hardy gave the continuous form of (1) in the following
where is continuous over , and in (1) and (2) is optimal.
In [3], Copson replaced the arithmetic mean of a sequence with a weighted arithmetic mean to create a new version of (1) as follows: Let and for all j. Then,
where , and if , then
In [4], Copson gave the continuous versions of (3) and (4), respectively, in the following: Let and g be nonnegative functions and Then,
and if then
where
In [5], Leindler demonstrated that if and then
In [6], Bennett explicated that if and then
In [7,8], Bennett and Leindler established the reverse versions of (3) and (4), respectively. In particular, they exemplified that if for all j and then
where and if then
Moreover, in [4], Copson established the continuous versions of (9) and (10), respectively, as follows: Let and g be nonnegative functions, and Then
where and if then
Newly, time scale delta calculus was introduced for the first time in 1988 by Hilger [9] to unify the theory of difference equations and the theory of differential equations. Since the appearance of this calculus, many mathematicians have used it to unify the discrete and continuous forms of numerous inequalities.
For example, in [10], the author proved the time scale versions of (1) and (2) in the following: Let and be a right-dense continuous function such that the delta integral exists as a finite number as follows
The authors of [11] constructed the following time scale versions of (5) and (6), respectively: Let Then,
and if then
where
Additionally, in [11], the authors constructed a time scale version of Leindler’s inequality (7) as follows: Let and Then,
where
In 2001, the time scale nabla calculus (or simply nabla calculus) was introduced by Atici and Guseinov. Any field that requires the study of both continuous and discrete data can benefit from nabla calculus. Recently, a lot of authors have contributed to the development of many inequalities on time scales. For example, in [12], Kayar et al. showed that if is nonnegative, ld-continuous and ▽-differentiable and if the ▽-integrable functions on where and , then
If and then
where
Furthermore, they proved that if and , then
If and , such that
then
Fractional calculus is a useful tool for both explaining physical phenomena and solving practical issues. A novel idea in both applied sciences and mathematics is the notion of fractional order derivatives and integrals, which will clarify some aspects of differential equations that are still unknown as well as some solutions to fractional order differential equations that have proven useless for solving other problems. In addition to fractional order derivatives and integrals, new derivatives and integrals aid in the solution of differential equations that are presented and resolved in classical analysis. Its applications in fields including engineering, biostatistics, and mathematical biology have also enhanced its contribution to the literature. Not only do fractional derivative and integral operators differ from one another in terms of singularity, locality, and kernels, but they also introduced new concepts to fractional analysis in terms of the utilizations regions and spaces they could cover. Fractional calculus and the theory of inequality have become the cornerstone of the literature today. Fractional calculus was the answer to the question of whether fractional derivatives and fractional integrals can be taken. Therefore, it has offered solutions to many problems in many disciplines. The most famous of the fractional approaches that are developing day by day are the Riemann–Liouville, Caputo, and Conformable fractional approaches. The theory of inequalities is one of the most important topics of recent research. In particular, its use in analysis, applied mathematics, and pure mathematics is very wide. One of the most studied of these inequalities is the Bennett–Leindler type inequality. The topic of fractional inequalities has received a great deal of attention in recent years, and many writers are now interested in proving the inequalities of this sort using a new fractional calculus called the conformable calculus. For example, in [13], Zakarya et al. proved an -conformable version of Hardy-type inequalities. One of those results is
wherer are rd-continuous and the -fractional differentiable functions on where and .
The symmetry properties of functions used to define an equation or inequality can be studied in order to determine solutions with particular properties. As far as inequalities are concerned, the study of special functions such as hypergeometric functions and special polynomials considering their symmetry properties may provide some interesting outcomes. Studies on symmetry properties for different types of operators and inequalities associated with the concept of time scales calculus may also be investigated. These properties and results are symmetrical to the properties of the differential superobligation that form the inequalities theorems. For generalizations and implementations of dynamic inequalities, we refer to the papers [14,15,16,17,18,19,20,21,22,23].
In this study, we generalized a number of Bennett and Leindler Hardy-type inequalities to a general time scale with the use of a straightforward Keller’s chain rule and Hölder’s inequality result for the -nabla-fractional derivative on time scales. We also extended our inequalities to discrete and continuous calculus in order to derive some more inequalities as specific cases. A variety of time scales, including and , were used to show the theorems for each kind of inequality.
2. Fundamental Concepts
In this section, we will cover the fundamentals of conformable fractional integrals and derivatives of order on the time scales that will be used in this paper (see [24,25]). A time scale is defined as any arbitrary non-empty closed subset of . A backward jump operator on time scales is defined by: For any function , the notation denotes Additionally, we define the function by
Definition 1
(Conformable-fractional derivative [26]).Suppose that is a function and Then, for , we define as the number that has the property that for each ∃ a neighborhood U of η s.t. we have
We say that is the conformable nabla fractional derivative of ψ of order α at Moreover, we say ψ is a conformable nabla fractional differentiable of order α on provided that is
Theorem 1
such that
([26]).Let be the nabla conformable -fractional differentiable and Then,
- (i)
- is a nabla conformable -fractional differentiable, and
- (ii)
- is a nabla conformable -fractional differentiable, and
- (iii)
- is a nabla conformable -fractional differentiable, and
Lemma 1
([26]).Assume is a continuous and nabla conformable -fractional differentiable at for and is continuously differentiable. Then, is a nabla conformable -fractional differentiable and
Definition 2
(Conformable-fractional integral [26]).For the nabla conformable -fractional integral of is
Theorem 2
([26]).Let and . If are ld-continuous functions, then
(i)
(ii)
(iii)
(iv)
(v)
Lemma 2
([26]).Assume that and are nabla conformable -fractional differentiables and . Then,
Lemma 3
(Hölder’s inequality [26]).Let such that If and , then
where and
3. Main Results and Some Corollaries
In this section, we will demonstrate the key findings of this article. Throughout this article, we will consider the integrals given to exist (i.e., to be convergent).
Theorem 3.
Suppose that is a time scale with and Furthermore, let χ and η be nonnegative ld-continuous and α-nabla fractional differentiable functions on . Define
If and then
Proof.
By applying the formula (23) to
with and we have
where
Since and in (27), then we see that
By (22) and , we obtain
Again using (22) and , we have
This leads to
and then we obtain
Substituting (29) and (30) into (28) yields
Raising (31) to the factor p, we have
By applying (25) to
with indices (note that where ) and
we see that
This implies that
By substituting (33) into (32), we obtain
This means that
which is (26). □
Remark 1.
Corollary 1.
If in Theorem 3, then
where
This is a new result for a conformable continuous calculus.
Remark 2.
Clearly, for and Corollary 1 corresponds to [12, Remark 3.2].
Corollary 2.
Remark 3.
Theorem 4.
Suppose that is a time scale with and Furthermore, let χ and η be nonnegative ld-continuous and α-nabla fractional differentiable functions on Assume is defined as in Theorem 3 such that
and define If and then
Proof.
By applying (24) to
with and we have
where This with and imply that
By utilizing (22) and , we obtain
By substituting (41) into (40) and using , we obtain
Again using (22) and , we have
This implies that
By substituting (43) into (42), we obtain
Raising (44) to the factor we obtain
The remainder of the proof is analogous to the proof of Theorem 3 and is thus omitted. □
Remark 4.
Corollary 3.
If in Theorem 4, then
where and
This is a new result for a conformable continuous calculus.
Remark 5.
Corollary 4.
Remark 6.
If in Corollary 4, then we obtain Remark 3.6 in [12].
Theorem 5.
Suppose that is a time scale with and In addition, let χ and η be nonnegative ld-continuous and α-nabla fractional differentiable functions on Assume that and . If and then
Proof.
Using (24) on
with and we obtain
where . This with and imply that
By utilizing (22) and , we obtain
By substituting (51) into (50) and using , we have
Additionally, according to (22) and we have
This implies that
By substituting (53) into (52), we obtain
Raising (54) to the factor we obtain
The remainder of the proof is analogous to the proof of Theorem 3 and is thus omitted. □
Remark 7.
Corollary 5.
Remark 8.
Corollary 6.
Remark 9.
For in (59), then we have ([12] Remark 3.9).
Theorem 6.
Suppose that is a time scale with and In addition, let χ and η be nonnegative ld-continuous and α-nabla fractional differentiable functions on Define and such that
If and then
Proof.
Remark 10.
Corollary 7.
If in Theorem 6, then
where and such that
This is a new result for a conformable continuous calculus.
Remark 11.
Corollary 8.
Remark 12.
For in (70), then we have [12] (Remark 3.12).
4. Conclusions
In this work, with the help of a simple consequence of Keller’s chain rule and Hölder inequality for the -conformable nabla calculus on time scales, we generalized several of Bennett and Leindler-type inequalities. We also expand our inequalities to a discrete and continuous calculus in order to derive some more inequalities as specific cases. By utilising Specht’s ratio and Kantorovich’s ratio in subsequent work, we will proceed to generalise more fractional dynamic inequalities. Additionally, utilising the findings from this study, researchers may be able to derive other generalisations for the dynamic Hardy inequality and its related inequalities.
Author Contributions
Software and writing—original draft, G.A. and H.M.R.; writing—review and editing, R.B. and M.Z. All authors have read and agreed to the published version of the manuscript.
Funding
Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2022R45), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.
Conflicts of Interest
The authors declare no conflict of interest.
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