Abstract
In this paper, we investigate some new generalizations and refinements for Hölder’s inequality and it’s reverse on time scales through the diamond- dynamic integral, which is defined as a linear combination of the delta and nabla integrals, which are used in various problems involving symmetry. We develop a number of those symmetric inequalities to a general time scale. Our results as special cases extend some integral dynamic inequalities and Qi’s inequalities achieved on time scales and also include some integral disparities as particular cases when .
MSC:
Primary 26D15; Secondary 39A13
1. Introduction
Hölder’s inequality is one of the greatest inequalities in pure and applied mathematics. As is well known, Hölder’s inequality plays a very important role in different branches of modern mathematics, such as linear algebra, classical real and complex analysis, probability and statistics, qualitative theory of differential equations and their applications. A large number of papers dealing with refinements, generalizations and applications of Hölder’s integral inequalities and their series symmetry in different areas of mathematics have appeared (see [1,2,3,4] and the references therein).
The classical Hölder’s inequality (see [5]) mentions that if and then
This inequality is reversed if (for we assume that , ).
The integral version of inequality (1) is given as if and with and then
This inequality is reversed if and if or .
As an application of Hölder’s inequality (2), Lazhar Bougoffa in [6] proved that if such that
then for and with we have
and then
Recently, a number of scientists ([7,8,9], p. 126, p. 3) have explored the reverse of Hölder’s inequality, the famous ones being: Let and if
then
See ( [1,10,11], p. 9, p. 206, p. 212).
Lately, Sulaiman [12] gave the reverse Hölder inequality as follows: Let , and be two positive functions satisfying
then
In [13], the authors established a new inequality with a weighted function that is improvement of the reverse Hölder’s inequality that, given in (7), is as follows: Let , , , and integrable functions on a weight function (measurable and positive) on . If
then
In [14], the authors proved the -integral version of Hölder’s inequalities (1) and (2) as follows:Let with and . Then
where and . This inequality is reversed if and if or .
In [15,16], the authors proved the -integral version of Hölder’s inequality (6) as follows: If with and , such that
then for and with , we have
As an application of (9), the authors in [16,17] proved that if with and such that
then for and with we have
and then
In [18], the researchers concluded some generalizations of the inequality (10) for time scale diamond- calculus. Specifically, they proved that, if with and are two positive functions satisfying
on the set . If with then
For the development of dynamic inequalities on a time scale calculus, we refer the reader to the articles in [19,20,21,22,23,24,25,26,27,28]. Although there are many results for time scale calculus in the sense of delta and nabla derivative, there is not much done for diamond- derivative. Therefore, the major contribution of this article is to extend the reverse of Hölder type inequalities for diamond- calculus and to unify them for the arbitrary time scale. The main theorems are inspired from the papers [12,13] which presents the time scale version of inequalities (7), (8) and (12) for diamond- calculus. By obtaining their diamond- versions, we can show the generalizations of these inequalities for different types of time scales , such as real numbers and integers.
2. Preliminaries
In this section, the fundamental theories of time scale delta and time scale nabla calculi will be presented. Time scale calculus whose detailed information can be found in [29,30] has been invented in order to unify continuous and discrete analysis.
A nonempty closed subset of is named a time scale which is signified by . For if and then the forward jump operator and the backward jump operator are defined as and , respectively. From the above two concepts, it can be mentioned that a point with is named right-scattered if right-dense if left-scattered if and left-dense if .
The -derivative of at , indicated by , is the number that enjoys the property that where there is a neighborhood U of , such that
The ∇-derivative of at indicated by is the number that enjoys the property that where there is a neighborhood V of , such that
A function is -continuous if it is continuous at each right-dense points in and exists as a finite number for all left-dense points in . The set represents the class of real, -continuous functions defined on . If , then there exists a function such that and the delta integral of is defined by
A function is -continuous if it is continuous at each left-dense points in and exists as a finite number for all right-dense points in . The set represents the class of real, -continuous functions defined on . If , then there exists a function such that and the nabla integral of is defined by
Now, we briefly introduce short introduction of diamond- derivative and integrals [17,31].
For , we define the diamond- dynamic derivative by
Thus, is diamond- differentiable if and only if is and ∇ differentiable. The diamond- derivative reduces to the standard -derivative for , or the standard ∇-derivative for . Moreover, the diamond- derivatives offer a centralized derivative formula on any uniformly discrete time scale when .
On the other hand, let and . Then the diamond- integral of w is defined by
We may note that the -integral is an integral combination of and ∇. Generally speaking, we have no
It is clear that the diamond- integral of w exists when w is a continuous function.
Within the following, we display some basic properties for diamond- calculus that play a key role in inaugurating the major findings of this paper.
Theorem 1
([17] [Theorem 1.3.5]). Let , , , and , v be continuous functions on . Then the following properties hold:
- (i)
- ;
- (ii)
- ;
- (iii)
- ;
- (iv)
- If then ;
- (v)
- If then
Theorem 2
([17] [Theorem 2.3.11, Theorem 2.3.12]). Assume with If with then
This inequality is reversed if or .
3. Main Results
In this section, we prove new diamond- inequalities. As particular cases we get -inequalities on time scales for and ∇-inequalities on time scales when . In the sequel, we will suppose that the functions (without mentioning) are non-negative continuous functions and the left hand side of the inequalities exists if the right hand side exists. In what follows, we will present the diamond -version of Hölder’s inequality (12) with a weight function by applying the diamond -Hölder inequality (14).
Theorem 3.
Let with and w a weight function (measurable and positive) on , such that
Then for with we have
and hence, we get
Proof.
Since and then from the above inequality it follows that
and so,
Hence, the inequality (16) is proven.
As a specific case of Theorem 3, when and we get the following findings.
Corollary 1.
Let with and w a weight function (measurable and positive) on , such that
Corollary 2.
Remark 1.
Remark 2.
As an application of (17) in Theorem 3, we get the next theorem.
Theorem 4.
Let such that and . If
with then for a given positive integer we have
Proof.
As a specific case of Theorem 4 when and we get the following findings.
Corollary 3.
Let n such that and . If
with then for a given positive integer we have
which is the delta version of (24), see [16] [Lemma 2.10].
Corollary 4.
Let n such that and . If
Remark 3.
In Theorem 4, if we make the substitution and with then the equality in (24) holds.
Remark 4.
For the particular case inequality (24) in Theorem 4 reduces to
which is Qi’s inequality (10) [32] [Proposition 2].
The following theorems include the reverse Hölder form on time-scales.
Theorem 5.
Let with and w a weight function (measurable and positive) on . If
then
Proof.
From the assumption (28), we have
By multiplying the right hand side of (31) by and integrating on and using properties (ii) and (v) in Theorem 1, we can write that
Similarly, from assumption (28), we get
Multiplying by and using the fact that we obtain
and then
Finally, we deduce that
As a specific case of Theorem 5 when and we get the following findings.
Corollary 5.
Let with and , w a weight function (measurable and positive) on . If
then
which is the delta version of (29).
Corollary 6.
Let with and , w a weight function (measurable and positive) on . If
which is the nabla version of (29).
Remark 5.
Remark 6.
In Corollary 5, if and we get the reverse Hölder type inequality
which is [16] [Corollary 2.2].
Remark 8.
As a particular state of Theorem 5, if then
Remark 9.
In Remark 8, if we replace and by u and v, we obtain the reverse Hölder type inequality
As an application of Hölder’s inequalities (38) and (39) in Remarks 8 and 9, we have the following theorems.
Theorem 6.
Let and with and . If
then
where
Corollary 7.
Let and with If
and on then
As a specific case of Theorem 6 and Corollary 7 when and we get the following findings.
Corollary 8.
Corollary 9.
Remark 10.
Theorem 7.
Let and with and . If
then
Proof.
Putting into Remark 8 yields
and so,
Therefore, we get
On the other hand, substituting in Remark 9 leads to
Further, taking the -th power on both sides of the above inequality yields
Hence,
This proves (52). □
Corollary 10.
In Theorem 7, if on and for then
As a specific case of Theorem 7 and Corollary 10 when and we get the following findings.
Corollary 11.
Corollary 12.
Remark 11.
Corollary 13.
Let and . If
then
and hence, we get
Remark 12.
For the particular case Corollary 13 coincides with Corollary 2.4 in [13].
Corollary 14.
Let and . If
then
and hence, we get
Remark 13.
For the particular case Corollary 14 coincides with Corollary 2.5 in [13].
Now, we present a refinement of inequality (7) on time scales.
Theorem 8.
Let with and . If
then
Proof.
As a specific case of Theorem 8 when we get the following findings.
Corollary 15.
As a specific case of Theorem 8 and Corollary 10 when and we get the following findings.
Corollary 16.
Corollary 17.
Remark 14.
4. Conclusions and Future Work
The study of dynamic inequalities depends on the diamond- integral on time scales. Hence, in the context of this article, we presented generalizations of symmetrical form for Hölder’s inequality and it is reverse by means of the diamond- integral, which is deflated as a linear combination of the delta and nabla integrals. Within this paper, we generalize certain delta and nabla-integrals inequalities on time scales to diamond- integrals. 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 time scale calculus. For future work, we can present such diamond- integrals inequalities by using Riemann–Liouville type fractional integrals and fractional derivatives on time scales. It will also be very interesting to present such diamond- integrals inequalities on quantum calculus.
Author Contributions
All authors contributed equally to the writing of this manuscript and 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.
Conflicts of Interest
The authors declare that they have no conflict of interest.
References
- Pecaric, J.; Pearce, C.E.M. On an inverse to the Hölder inequality. Int. J. Math. Math. Sci. 1997, 20, 205–207. [Google Scholar] [CrossRef]
- Qiang, H.; Hu, Z. Generalizations of Hölder’s and some related inequalities. Compt. Math. Appl. 2011, 61, 392–396. [Google Scholar] [CrossRef]
- Wu, S. A new sharpened and generalized version of Hölder’s inequality and its applications. Appl. Math. Comput. 2008, 197, 708–714. [Google Scholar] [CrossRef]
- Yang, X. A generalization of Hölder inequality. J. Math. Anal. Appl. 2000, 247, 328–330. [Google Scholar] [CrossRef]
- Hölder, O. Uber einen Mittelwerthssatz. Nachr. Ges-Wiss. Gott. 1889, 1889, 38–47. [Google Scholar]
- Bougoffa, L. An integral inequality similar to Qi’s inequality. J. Inequal. Pure Appl. Math. 2005, 1, 1–3. [Google Scholar]
- Mitrinovic, D.S.; Pecaric, J.; Fink, A.M. Classical and New Inequalities Inanalysis; Springer Science and Business Media: New York, NY, USA, 2013; Volume 61, pp. 126–127. [Google Scholar]
- Saitoh, S.; Tuan, V.K.; Yamamoto, M. Reverse convolution inequalities and applications to inverse heat source problems. J. Inequal. Pure Appl. Math. 2002, 3, 80. [Google Scholar]
- Xiao-Hua, L. On the inverse of Hölder inequality. Math. Pract. Theory 1990, 1, 84–88. [Google Scholar]
- Halim, B.; Senouci, A. Some generalizations involving open problems of F. Qi. Int. J. Open Probl. Compt. Math. 2019, 12, 10–21. [Google Scholar]
- Zhao, C.J.; Cheung, W.S. Hölder’s reverse inequality and its applications. Publ. Inst. Math. 2016, 99, 211–216. [Google Scholar] [CrossRef]
- Sulaiman, W.T. Reverses of Minkowski’s, Hölder’s, and Hardy’s integral inequalities. Int. J. Mod. Math. Sci. 2012, 1, 14–24. [Google Scholar]
- Benaissa, B.; Budak, H. More on reverse of Hölder’s integral inequality. Korean J. Math. 2020, 28, 9–15. [Google Scholar]
- Agarwal, R.; Bohner, M.; Peterson, A. Inequalities on time scales: A survey. Mathl. Inequal. Appl. 2001, 7, 535–557. [Google Scholar] [CrossRef]
- Tuna, A.; Kutukcu, S. Some integral inequalities on S. time scales. Appl. Math. Mech. 2008, 29, 23–29. [Google Scholar] [CrossRef]
- Sarikaya, M.Z.; Ozkan, U.M.; Ylldirim, H. Time scale integral inequalities similar to Qi’s inequality. J. Inequal. Pure Appl. Math. 2006, 7, 1–7. [Google Scholar]
- Agarwal, R.; O’Regan, D.; Saker, S.H. Dynamic Inequalities on Time Scales; Springer International Publishing: Cham, Switzerland, 2014. [Google Scholar]
- Ammi, M.R.S.; Torres, D.F.M. Hölder’s and Hardy’s two dimensional diamond-alpha inequalities on time scales. Ann. Univ. Craiova Math. Comp. Sci. Ser. 2010, 37, 1–11. [Google Scholar]
- Ahmed, A.M.; AlNemer, G.; Zakarya, M.; Rezk, H.M. Some dynamic inequalities of hilbert’s type. J. Fun. Spaces 2020, 1–13. [Google Scholar] [CrossRef]
- Abd El-Hamid, H.A.; Rezk, H.M.; Ahmed, A.M.; AlNemer, G.; Zakarya, M.; El Saify, H.A. Dynamic Inequalities in Quotients with General Kernels and Measures. J. Fun. Spaces 2020, 1–12. [Google Scholar] [CrossRef]
- Saker, S.H.; Kenawy, M.R.; AlNemer, G.; Zakarya, M. Hardys Type Via Conformable Calculus. J. Math. 2020, 434, 1–15. [Google Scholar]
- AlNemer, G.; Zakarya, M.; Abd El-Hamid, H.A.; Agarwal, P.; Rezk, H.M. Some Dynamic Hilbert-Type Inequalities on Time Scales. Symmetry 2020, 12, 1410. [Google Scholar] [CrossRef]
- AlNemer, G.; Zakarya, M.; Abd El-Hamid, H.A.; Kenawy, M.R.; Rezk, H.M. Dynamic Hardy-type inequalities with non-conjugate parameters. Alex. Eng. J. 2020, 1–10. [Google Scholar] [CrossRef]
- Agarwal, P.; Hyder, A.; Zakarya, M.; AlNemer, G.; Cesarano, C.; Assante, D. Exact Solutions for a Class of Wick-Type Stochastic (3+1)-Dimensional Modified Benjamin-Bona-Mahony Equations. Axioms 2019, 8, 134. [Google Scholar] [CrossRef]
- O’Regan, D.; Rezk, H.M.; Saker, S.H. Some dynamic inequalities involving hilbert and hardy-hilbert operators with kernels. Res. Math. 2018, 73, 1–22. [Google Scholar] [CrossRef]
- Saker, S.H.; Rezk, H.M.; O’Regan, D.; Agarwal, R.P. A variety of inverse hilbert type inequality on time scales. Dyn. Contin. Discret. Impuls. Syst. Ser. A Math. Anal. 2017, 24, 347–373. [Google Scholar]
- Saker, S.H.; Rezk, H.M.; Krnić, M. More accurate dynamic hardy-type inequalities obtained via superquadraticity. Rev. Real Acad. Cienc. Exactas Fís. Nat. Ser. A Mat. 2019, 113, 2691–2713. [Google Scholar] [CrossRef]
- Saker, S.H.; Rezk, H.M.; Abohela, I.; Baleanu, D. Refinement multidimensional dynamic inequalities with general kernels and measures. J. Inequal. Appl. 2019, 306, 1–16. [Google Scholar] [CrossRef]
- Bohner, M.; Peterson, A. Dynamic Equations on Time Scales: An Introduction with Applications; Birkhäuser: Boston, MA, USA, 2001. [Google Scholar]
- Bohner, M.; Peterson, A. (Eds.) Advances in Dynamic Equations on Time Scales; Birkhäuser: Boston, MA, USA, 2003. [Google Scholar]
- Sheng, Q.; Fadag, M.; Henderson, J.; Davis, J.M. An exploration of combined dynamic derivatives on time scales and their applications. Nonlinear Anal. Real World Appl. 2006, 7, 395–413. [Google Scholar] [CrossRef]
- Qi, F. Several integral inequalities. J. Inequal. Pure Appl. Math. 2000, 1, 1–7. [Google Scholar]
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