Abstract
In this article, we prove some new fractional dynamic inequalities on time scales via conformable calculus. By using chain rule and Hölder’s inequality on timescales we establish the main results. When we obtain some well-known time-scale inequalities due to Hardy, Copson, Bennett and Leindler inequalities.
Keywords:
fractional hardy’s inequality; fractional bennett’s inequality; fractional copson’s inequality; fractional leindler’s inequality; timescales; conformable fractional calculus; fractional hölder inequality MSC:
26A15; 26D10; 26D15; 39A13; 34A40; 34N05
In 1920, Hardy [1] established the inequality
where is a positive sequence defined for all . After that, Hardy [2], by using the calculus of variations, proved the continuous inequality of (1) which has the form
for a given positive function g, which is integrable over and is convergent and integrable over and . In (1) and (2), is a sharp constant. As a generalization of (2), Hardy [3] showed that when , then
and
The constants and in (3) and (4) are the best possible. Copson [4] demonstrated that if , and is integrable on the interval , then
converges for and
where is the best possible constant. Some of the generalizations of the discrete Hardy inequality (1) and the discrete version of (5) and its extensions are due to Leindler, we refer to the papers the papers [5,6,7,8]. For example, Leindler in [5] proved that if , , then
and
The converses of (6) and (7) are proved by Leindler in [6]. He proved that if , then
and
For more generalization Copson in [9] showed that if , , , , , and , then
and if and , then
The integral versions of the inequalities (10) and (11) was proved by Copson in [10] (Theorems 1 and 3). In particular, he proved that if , , and , then
where , and if , , then
where Leindler in [5] and Bennett in [11] presented interesting different inequalities. Leindler established that if , , and , then
and Bennett in [11] showed that if , then
In last decades, studying the dynamic equations and inequalities on time scales become a main field in applied and pure mathematics, we refer to [12,13,14] and the references they are cited. In fact, the book [13] includes forms of the above inequalities on time-scale and their extensions. The timescales idea is returned to Stefan Hilger [15], who investigated the research of dynamic equations on timescales. The books by Bohner and Peterson in [16,17] summarized and organized most timescales calculus. The three most common timescales calculuses are difference, differential, and quantum calculus (see [18]), i.e., at , and where .
In recent years, a lot of work has been published for fractional inequalities and the subject becomes an active field of research and several authors were interested in proving inequalities of fractional type by using the Riemann-Liouville and Caputo derivative (see [19,20,21]).
On the other hand, the authors in [22,23] introduced a new fractional calculus called the conformable calculus and gave a new definition of the derivative with the base properties of the calculus based on the new definition of derivative and integrals. By using conformable calculus, some authors have studied classical inequalities like Chebyshev’s inequality [24], Hermite-Hadamard’s inequality [25,26,27], Opial’s inequality [28,29] and Steffensen’s inequality [30].
The main question that arises now is: Is it possible to prove new fractional inequalities on timescales and give a unified approach of such studies? This in fact needs a new fractional calculus on timescales. Very recently Torres and others, in [31,32], combined a time scale calculus and conformable calculus and obtained the new fractional calculus on timescales. So, it is natural to look on new fractional inequalities on timescales and give an affirmative answer to the above question.
In particular, in this paper, we will prove the fractional forms of the classical Hardy, Bennett, Copson and Leindler inequalities. The paper is divided into two sections. Section 2 is an introduction of basics of fractional calculus on timescales and Section 3 contains the main results.
1. Preliminaries and Basic Lemmas
We present the fundamental results about the fractional timescales calculus. The results are adapted from [16,17,31,32]. A time-scale is non-empty closed subset of ( is the real numbers). The operators of backward jump and forward jump express of the closest point on the right and left of t is defined by, respectively:
where and ( denotes the empty set), for any the notation refer to i.e., . The graininess function , , defined by .
Definition 1.
The number(provided it exists) of the function, forandis the number which has the property that for anythere exists a neighborhood U of t S. T.
is called the conformablefractional derivative of function f of order α at t, for conformable fractional derivative onat 0, we define it with
The conformable fractional derivative has the following properties.
Theorem 1.
Letare conformable fractional derivative from order, then the following properties are hold:
- (i)
- Theis conformable fractional derivative and
- (ii)
- Fora all, thenisfractional differentiable and
- (iii)
- If v and u arefractional differentiable, we haveisfractional differentiable and
- (iv)
- If v isfractional differentiable, thenisfractional differentiable with
- (v)
- If v and u arefractional differentiable, then is fractional differentiable withvalid , where
Lemma 1.
Letis continuous andfractional differentiable atfor, andis continuous and differentiable. Then there exists dwith
Lemma 2.
Letis continuously differentiable,, andbefractional differentiable. Thenisfractional differentiable and we have
Definition 2.
Letthefractional integral of, is defined as
The conformable fractional integral satisfying the next properties.
Theorem 2.
Assume a, b,,. Let u,. Then
- (i)
- (ii)
- (iii)
- (iv)
- (v)
Lemma 3.
Assumebe a time-scale, a,where. Let u, v are conformable—fractional differentiable,. Then the formula of integration by parts is given by
Lemma 4.
Assumebe a time-scale, a,and,. Let u,. Then
whereand
2. Main Results
Throughout the paper, we will assume that the functions are nonnegative on and its integrals exist and are finite. We start with the fractional time-scale inequality of Copson’s type.
Theorem 3.
Assumek, define
If
then
Proof.
By employing the formula of integration by parts (20) on the term
with and , we have that
where
By using the chain rule (18), we obtain that
Then we have
and thus
This leads to
that is the desired inequality (22). The proof is complete. □
Corollary 1.
Atin Theorem 3, we obtain the inequality
that is the timescales version of inequality (2.8) in [33].
Corollary 2.
At, andin Theorem 3, we obtain the integral inequality
which is of Copson type.
Corollary 3.
Theorem 4.
Letand. Define
If
then
Proof.
By using chain rule (18), then for we get that
So
and then,
This leads to
that is the desired inequality (26). The proof is complete. □
Corollary 4.
Atin Theorem 4, then
which is the timescales version inequality (2.22) in [33].
Corollary 5.
At, and Tin Theorem 4, we obtain the next integral inequality
which considered an extension of Hardy’s inequality (4) as in the following corollary.
Corollary 6.
A generalization of Leindler’s inequality (14) on fractional time scales will be proved in the next theorem.
Theorem 5.
Assume, define
If
then
Proof.
By chain rule (18), we see for that
This leads to
that is the desired inequality (30). The proof is complete. □
Corollary 7.
Atin Theorem 5, we get
which inequality (2.36) in [33].
A generalization of Bennett’s inequality (15) on fractional timescales will be proved in the next theorem.
Theorem 6.
Assume,, and define
If
then
Proof.
This leads to
that is the desired inequality (34). The proof is complete. □
Corollary 8.
Atin Theorem 5, we have the inequality
which the inequality (2.49) in [33].
3. Conclusions
The new fractional calculus on timescales is presented with applications to some new fractional inequalities on timescales like Hardy, Bennett, Copson and Leindler types. Inequalities are considered in rather general forms and contain several special integral and discrete inequalities. The technique is based on the applications of well-known inequalities and new tools from fractional calculus.
Author Contributions
S.S. contributed in preparing the introduction, preliminaries and formulate theorem 3, its proof and its corollaries (cor.1, cor. 2 and cor.3). M.K. contributed in preparing the introduction, preliminaries and formulate theorem 4, its proof and its corollaries (cor.4, cor. 5 and cor.6). G.A. contributed in preparing the introduction, preliminaries and formulate theorem 5, its proof and its corollaries (cor.7). M.Z. contributed in preparing the introduction, preliminaries and formulate theorem 6, its proof and its corollaries (cor.8). All authors contributed equally to the writing of this manuscript. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Program.
Acknowledgments
This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Program. The authors thank the referees for helpful comments that lead to the improvement of the presentation of the results in this paper.
Conflicts of Interest
The authors declare no conflict of interest.
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