1. Introduction
The form of the established classical discrete Hardy–Hilbert double series inequality [
1] is given as follows: If
,
,
and
then we have
where
,
.
The continuous versions of inequality (
1) is given by:
unless
or
where
f and
g are measurable non-negative functions such that
and
. The constant
in (
1) and (
2), is the best possible.
In [
2], Pachpatte proved that if
with
and
q are two positive functions defined for
and
with
and
for
and
, where
y are positive real numbers. Let
and
be two real-valued non-negative, convex and sub-multiplicative functions defined on
Then,
where
In 2004, Yong [
3] studied the following integral inequality:
Theorem 1. Let and for , where ζ are positive real numbers and definefor and Then, for or unless or where In 2009, Yang [
4] studied the following integral inequality:
Theorem 2. Let and for , where ζ are positive real numbers and definefor and Then,unless or where In this paper, we prove some new dynamic inequalities of Hilbert type and their converses on time scales. From these inequalities, as special cases, we formulate some special integral and discrete inequalities. Symmetry plays an essential role in determining the correct methods to solve dynamic inequalities.
Now, we present some fundamental concepts and effects on time scales which are beneficial for deducing our main results. In 1988, S. Hilger [
5] presented time scale theory to unify continuous and discrete analysis. For some Hilbert-type integral, dynamic inequalities and other types of inequalities on time scales, see the papers [
2,
3,
6,
7,
8,
9,
10,
11,
12,
13,
14,
15,
16]. For more details on time scale calculus see [
17].
We need the following important relations between calculus on time scales and either continuous calculus on or discrete calculus on . Note that:
Next, we write Hölder’s inequality and Jensen’s inequality on time scales.
Lemma 1 (Dynamic Hölder’s Inequality [
18]).
Let and f, . If p, with , then This inequality is reversed if and if or Lemma 2 (Dynamic Jensen’s Inequality [
18]).
Let a, and c, . Assume that and are non-negative with . If is a convex function, then This inequality is reversed if is concave. Moreover, we use the following definition and lemma as we see in the proof of our results:
Definition 1. Λ
is called a supermultiplicative function on if Lemma 3 ([
19]).
Let be a time scale with such that If and then Now, we present the formula that reduces double integrals to single integrals, which is desired in [
9].
Lemma 4. Let and Then,assuming the integrals considered exist. The following section contains our main results:
2. Main Results
In the next theorems, we assume that and
Theorem 3. Let be time scale with and ζ Assume and are two non-negative and right-dense continuous functions on and , respectively, and definethen, for and we have thatwhere Proof. By using the inequality (
11), we obtain
Applying inverse Hölder’s inequality on the right hand side of (
14) with indices
p and
we have
Applying inverse Hölder’s inequality on the right hand side of (
15) with indices
and
we also have that
From (
16) and (
17), we obtain
Using the following inequality
where
and
Now, by setting
and
we obtain that
Substituting (
20) in (
18), yields
Dividing both side of (
21) by
, we obtain that
Integrating both sides of (
22) from
to
and from
to
, and applying inverse Hölder’s inequality with indices
and
we obtain
Applying Lemma 4 on the right hand side of (
23), we have
By using the facts
and
we obtain
This completes the proof. □
Theorem 4. Let and be defined as Theorem 3. Then, we have Proof. Put
in (
13). This completes the proof. □
As a special case of Theorem 3, when , we have , and we obtain the following result:
Corollary 1. Assume that and are non-negative functions and define and Then, As special case of Theorem 3, when , we have , and we obtain the following result:
Corollary 2. Assume that and are non-negative sequences and defineThen, Theorem 5. Let be a time scale with and be as defined in Theorem 3. Let and be two non-negative and right-dense continuous functions on and , respectively. Suppose that Λ and Υ are non-negative, concave and supermultiplicative functions defined on . Furthermore, assume thatthen, for and we have thatwhere Proof. Since
is a concave and supermultiplicative function, we obtain by applying inverse Jensen’s inequality that
Applying inverse Hölder’s inequality with indices
p and
on the right hand side of (
26), we see that
Moreover, since
is a concave and supermultiplicative function, we obtain by applying inverse Jensen’s inequality and inverse Hölder’s inequality with indices
and
that we have
From (
27) and (
28), we have
By using inequality (
19), we obtain that
From (
29) and (
30), we have that
Then,
Integrating both sides of (
32) from
to
and from
and
, we obtain
Applying inverse Hölder’s inequality with indices
and
on the right hand of side (
33), we have
Applying Lemma 4 on the right hand side of (
34), we obtain
By using the facts
and
we obtain
where
This completes the proof. □
As a special case of Theorem 5, when , we have , and we obtain the following result:
Corollary 3. Assume that and are non-negative functions and defineThen,where As a special case of Theorem 5, when , we have , and we obtain the following result.
Corollary 4. Assume that and are non-negative sequences and defineThen,where Theorem 6. Let be a time scale with Let f and g be two non-negative and right-dense continuous functions on and , respectively. Suppose that Λ and Υ are non-negative, concave and supermultiplicative functions defined on and definethen, for and we have thatwhere Proof. By assumption and by using the inverse Jensen inequality, we see that
By applying inverse Hölder’s inequality on (
37) with indices,
we have
This implies that
Analogously,
From (
39) and (
40), we obtain
By using inequality (
19), we obtain that
Then,
From (
43), we have
Taking delta integrating on both sides of (
44), first over
ℑ from
to
and then over
from
to
we find that
By applying inverse Hölder’sinequality on (
45) with indices
and
we get
Applying Lemma 4 on (
46), we fined that
By using the facts
and
we obtain
where
This completes the proof. □
As a special case of Theorem 6, when we obtain the following conclusion.
Corollary 5. Assume that f and g are non-negative functions and definethen, for and we have thatwhere As a special case of Theorem 6, when we obtain the following conclusion.
Corollary 6. Assume that and are two non-negative sequences of real numbers and definethen,where Theorem 7. Let be a time scale with Let and be two non-negative and right-dense continuous functions on and , respectively. Let Λ and Υ be as assumed in Theorem 5. Furthermore, assume thatthen, for and we have thatwhere Proof. From (
47), we see that
Applying inverse Hölder’s inequality with indices
p and
on the right hand side of (
48), we obtain
From (
49), we obtain that
Similarly, we obtain
From (
50) and (
51), we observe that
Applying the inequality (
19) on the term
we obtain the following inequality
Dividing both sides of (
53) by
we obtain that
Integrating both sides of (
54) from
to
and
to
we obtain
Applying inverse Hölder’s inequality again with indices
and
on the right hand side of (
55), we have
Applying Lemma 4 on the right hand side of (
56), we obtain that
By using the facts
and
we obtain
This completes the proof. □
As a special case of Theorem 7, when , we have , and we obtain the following result:
Corollary 7. Assume that and are non-negative functions and defineThen,where As a special case of Theorem 7, when , we have , and we obtain the following result:
Corollary 8. Assume that and are non-negative sequences and defineThenwhere 3. Conclusions and Discussion
In this article, with the help of the inverse Hölder’s inequality and inverse Jensen’s inequality on time scales, we discussed and proved several new generalizations of the integral retarded inequalities given in [
3]. Moreover, we generalized a number of other inequalities to a general time scale. Finally, as a special case, we studied the discrete and continuous inequalities. As a future work, we intend to generalize these inequalities by using alpha-conformable fractional derivatives on time scales. Furthermore, we will extend these results to diamond alpha calculus.
Author Contributions
Conceptualization, A.A.E.-D., S.D.M. and B.A.; formal analysis, A.A.E.-D., S.D.M. and B.A.; investigation, A.A.E.-D., S.D.M. and B.A.; writing–original draft preparation, A.A.E.-D., S.D.M. and B.A.; writing–review and editing, A.A.E.-D., S.D.M. and B.A. All authors have read and agreed to the published version of the manuscript.
Funding
Princess Nourah bint Abdulrahman University Researchers Supporting Project number PNURSP2022R216, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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