Abstract
In this article, we will prove some new diamond alpha Hilbert-type dynamic inequalities on time scales which are defined as a linear combination of the nabla and delta integrals. These inequalities extend some known dynamic inequalities on time scales, and unify and extend some continuous inequalities and their corresponding discrete analogues. Our results will be proven by using some algebraic inequalities, diamond alpha Hölder inequality, and diamond alpha Jensen’s inequality on time scales.
1. Introduction
Over the past decade, a great number of dynamic Hilbert-type inequalities on time scales has been established by many researchers who were motivated by various applications; see the papers [,,,].
For example, Pachpatte [] proved that if are two non-negative sequences of real numbers defined for and with and are two positive sequences of real numbers defined for and where r are natural numbers. Further and and and are two real-valued non-negative, convex, and submultiplicative functions defined on then
where
Additionally, in the same paper [], Pachpatte proved that if with and are two positive functions defined for and and for and where are positive real numbers; thus
where
Under the same conditions as seen above, with few modifications, Handley et al. [] extended (1) and (2) as follows:
and
where and
In [], Pachpatte established the following Hilbert-type integral inequalities under the following conditions: If and for and where and are positive real numbers and define and for and then
and
where
and
where
A time scale is an arbitrary, non-empty, closed subset of the set of real numbers . Throughout the article, we assume that has the topology that it inherits from the standard topology on . We define the forward jump operator for any by
and the backward jump operator for any by
In the preceding two definitions, we set (i.e., if is the maximum of , then ) and (i.e., if is the minimum of , then ), where ∅ denotes the empty set.
A point with is said to be right-scattered if , right-dense if , left-scattered if , and left-dense if . Points that are simultaneously right-dense and left-dense are said to be dense points, whereas points that are simultaneously right-scattered and left-scattered are said to be isolated points.
The forward graininess function is defined for any by .
If is a function, then the function is defined by , that is . Similarly, the function is defined by ; that is, .
The sets , and are introduced as follows: if has a left-scattered maximum , then , otherwise . If has a right-scattered minimum , then , otherwise . Finally, we have .
The interval in is defined by
We define the open intervals and half-closed intervals similarly.
Assume is a function and . Then is said to be the delta derivative of at if for any there exists a neighborhood U of such that, for every , we have
Moreover, is said to be delta differentiable on if it is delta differentiable at every .
Similarly, we say that is the nabla derivative of at if, for any , there is a neighborhood V of , such that for all
Furthermore, is said to be nabla differentiable on if it is nabla differentiable at each .
A function is said to be right-dense continuous (rd-continuous) if is continuous at all right-dense points in and its left-sided limits exist at all left-dense points in .
In a similar manner, a function is said to be left-dense continuous (ld-continuous) if is continuous at all left-dense points in and its right-sided limits exist at all right-dense points in .
The delta integration by parts on time scales is given by the following formula
whereas the nabla integration by parts on time scales is given by
The following relations will be used.
- (i)
- If , then
- (ii)
- If , thenwhere and ∇ are the forward and backward difference operators, respectively.
Now we will introduce the diamond- calculus on time scales, and we refer the interested reader to [,] for further details on the definitions of nabla and delta integrals and derivatives.
If is a time scale, and is a function that is delta and nabla differentiable on ,then, for any , the diamond- dynamic derivative of at , denoted by , is defined by
We conclude from the last relation that a function is diamond- differentiable if and only if it is both delta and nabla differentiable. For , the diamond- derivative boils down to a delta derivative, and for it boils down to a nabla derivative.
Assume , are diamond- differentiable functions at , and let . Then
- (i)
- ;
- (ii)
- ;
- (iii)
- .
Let be a continuous function. Then the definite diamond- integral of is defined by
Let a, b, , . Then,
- (i)
- ;
- (ii)
- ;
- (iii)
- ;
- (iv)
- ;
- (v)
- ;
- (vi)
- if on , then ;
- (vii)
- if on , then ;
- (viii)
- .
Let be a differentiable function on . Then is increasing if , non-decreasing if , decreasing if , and non-increasing if on .
Next, we write Hölder’s inequality and Jensen’s inequality on time scales.
Lemma 1
(Dynamic Hölder’s Inequality []). Suppose with Assume be integrable functions and with then
This inequality is reversed if and if or
Lemma 2
(Dynamic Jensen’s inequality []). Let , and If and is convex then
This inequality is reversed if is concave.
Definition 1.
Φ is called a supermultiplicative function on if
In this paper, we extend some generalizations of the integral Hardy–Hilbert inequality to a general time scale using diamond alpha calculus. As special cases of our results, we will recover some dynamic integral and discrete inequalities known in the literature.
Now we are ready to state and prove our main results.
2. Main Results
First, we enlist the following assumptions for the proof of our main results:
- (S1)
- be time scales with
- (S2)
- are non-negative, diamond-Alpha integrable functions defined on
- (S3)
- have partial -derivatives and with respect and , respectively.
- (S4)
- All functions used in this section are integrable according to sense.
- (S5)
- (S6)
- are n positive diamond-Alpha integrable functions defined for
- (S7)
- and are positive diamond-Alpha integrable functions defined for
- (S8)
- are n real-valued non-negative concave and supermultiplicative functions defined on
- (S9)
- and are positive real numbers.
- (S10)
- and
- (S11)
- (S12)
- (S13)
- (S14)
- (S15)
- (S16)
- (S17)
- and
- (S18)
- (S19)
- (S20)
- (S21)
- (S22)
- (S23)
- is positive real number.
- (S24)
- (S25)
- (S26)
- are n positive functions.
- (S27)
- (S28)
- (S29)
Now, we are ready to state and prove the main results that extend several results in the literature.
Theorem 1.
Let , , and be satisfied. Then for and we find that
where
Proof.
From the hypotheses of Theorem 1, and it is easy to observe that
By using inverse Jensen dynamic inequality, we obtain that
Applying inverse Hölder’s inequality on the right hand side of (21) with indices and it is easy to observe that
By using the following inequality on the term
we get that
Integrating both sides of (24) over from to we obtain that
Applying inverse Hölder’s inequality on the right hand side of (25) with indices and it is easy to observe that
Using Fubini’s theorem, we observe that
By using the fact and we get that
This completes the proof. □
Remark 1.
In Theorem 1, if , we get the result due to Zhao et al. ([], Theorem 2).
As a special case of Theorem 1, when , we have we get the following result.
Corollary 1.
Let and be n sequences of non-negative numbers defined for and and define
Then
where
Remark 2.
Let and change to and respectively; with suitable changes, we have the following new corollary:
Corollary 2.
Let and be satisfied. Then for and we have that
where
Corollary 3.
Remark 3.
This is an inverse of the inequality (6) which was proved by Pachpatte [].
Corollary 4.
Theorem 2.
Let , and be satisfied. Then for and we have that
Proof.
From the hypotheses of Theorem 2, and by using inverse Jensen dynamic inequality, we have
Applying inverse Hölder’s inequality on the right hand side of (32) with indices and it is easy to observe that
By using the inequality (23), on the term we get that
Integrating both sides of (33) over from to we get that
Applying inverse Hölder’s inequality on the right hand side of (25) with indices and it is easy to observe that
By using Fubini’s theorem, we observe that
By using the fact and we get that
This completes the proof. □
Remark 4.
In Theorem 2, if , we get the result due to Zhao et al. ([], Theorem 3).
As a special case of Theorem 2, when , we have we get the following result.
Corollary 5.
Let and be n sequences of non-negative numbers defined for and and define
Then
Remark 5.
Let and
changes to and
respectively, and with suitable changes, we have the following new corollary:
Corollary 6.
Let and be satisfied. Then, for and , we have that
Corollary 7.
In Corollary 6, if we take then the inequality (28) changes to
Remark 6.
In Corollary 7, if we take then the inequality (37) changes to
This is an inverse of the inequality (7), which was proven by Pachpatte [].
Corollary 8.
In Corollary 7, let then Therefore, inequality (37) changes to
Remark 7.
In Corollary 8, if we take then inequality (39) changes to
This is an inverse inequality of the following inequality which was proven by Pachpatte [].
Corollary 9.
In Corollary 6, if we take the inequality (30)
Theorem 3.
Let , and be satisfied. Then, for we have that
where
Proof.
From the hypotheses of Theorem 3, we obtain
From (41) and , it is easy to observe that
By using inverse Jensen’s dynamic inequality, we get that
Applying inverse Hölder’s inequality on the right hand side of (43) with indices and we obtain
Using the following inequality on the term where and
We obtain that
From (46), we have that
Integrating both sides of (47) over from to we get that
Applying inverse Hölder’s inequality on the right hand side of (48) with indices and we obtain
By using Fubini’s theorem, we observe that
By using the fact and we get that
This completes the proof. □
Remark 8.
In Theorem 3, if , we get the result due to Zhao et al. ([], Theorem 1.5).
Remark 9.
In Theorem 3, if we take , we get the result due to Zhao et al. ([], Theorem 1.6).
Remark 10.
Let and be satisfied and let and be as Theorem 3. Similar to proof of Theorem 3, we have
where
This is an inverse form of the inequality (40).
Corollary 10.
Let and be satisfied. Then we have that
where
Remark 11.
In Corollary 10, if we take we get an inverse form of inequality (3), which was given by Handley et al.
Remark 12.
In Corollary 10, if we take we get an inverse form of inequality (4), which was given by Handley et al.
Remark 13.
Remark 14.
3. Conclusions
In this work, by applying calculus, defined as a linear combination of the nabla and delta integrals, we introduced some novel results of Hardy–Hilbert-type inequalities on a general time-scale. Furthermore, we gave the multidimensional generalization for these inequalities to time scales. We also applied our inequalities to discrete and continuous calculus to obtain some new inequalities as special cases.
Author Contributions
Conceptualization, A.A.E.-D., D.B., C.C. and A.A.; formal analysis, A.A.E.-D., D.B., C.C., S.S.A. and A.A.; investigation, A.A.E.-D., D.B., C.C. and A.A.; writing—original draft preparation, A.A.E.-D., D.B., C.C. and A.A.; writing—review and editing, A.A.E.-D., D.B., C.C., S.S.A. and A.A. 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 that they have no competing interest.
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