Preprint
Article

Similar Formulas to Hilbert-Type Inequalities on Time Scales Delta Calculus

Altmetrics

Downloads

63

Views

15

Comments

0

A peer-reviewed article of this preprint also exists.

Submitted:

17 October 2023

Posted:

31 October 2023

You are already at the latest version

Alerts
Abstract
In this article, we establish some new generalized inequalities of Hilbert-type on time scales delta calculus which considered as similar formulas for inequalities of Hilbert type proved by Chang-Jian, Lian-Ying and Cheung [7]. These inequalities will proved by applying Hölder’s inequality, chain rule on time scales and the mean inequality. As special cases of our results (when T = N and T = R), we get the discrete and continuous inequalities. Also, we can obtain other inequalities in different time scale, like T = q^Z, q > 1.
Keywords: 
Subject: Computer Science and Mathematics  -   Applied Mathematics

MSC:  26D10; 26D15; 34N05; 47B38; 39A12

1. Introduction

During the early 1900s, Hilbert made the discovery of this inequality (refer to [10])
n = 1 s = 1 a s c n s + n π s = 1 a s 2 1 2 n = 1 c n 2 1 2 .
Here, { a s } s = 1 and { c n } n = 1 are real sequences satisfying 0 < s = 1 a s 2 < and 0 < n = 1 c n 2 < . This particular expression is known as Hilbert’s double series inequality.
In [17], Schur demonstrated that π in (1) is the most optimal constant achievable. Additionally, he unveiled the integral counterpart of (1), which later became recognized as the Hilbert integral inequality, taking the form
0 0 f ( η ) g ( τ ) η + τ d η d τ π 0 f 2 ( η ) d η 1 2 0 g 2 ( τ ) d τ 1 2 ,
where f , g are measurable functions satisfying 0 < 0 f 2 ( η ) d η < and 0 < 0 g 2 ( τ ) d τ < .
In [8], an extension of (1) is presented as follows: suppose l , r > 1 with 1 / l + 1 / r = 1 , { a s } s = 1 , { c n } n = 1 are real sequences satisfying 0 < s = 1 a s r < and 0 < n = 1 c n l < , then
n = 1 s = 1 a s c n s + n π sin π r s = 1 a s r 1 r n = 1 c n l 1 l .
Here, π / sin ( π / r ) is the optimal constant.
In [9], the authors derived the integral counterpart of (3) as
0 0 f ( η ) g ( τ ) η + τ d η d τ π sin π r 0 f r ( η ) d η 1 r 0 g l ( τ ) d τ 1 l .
Here, f , g 0 are measurable functions satisfying 0 < 0 f r ( η ) d η < and 0 < 0 g l ( τ ) d τ < .
In [14], new inequalities akin to the ones presented in (3) and (4) were established as follows: let l , r > 1 with 1 / l + 1 / r = 1 . Consider sequences a w : 0 , 1 , 2 , . . . , s N R and c ϑ : 0 , 1 , 2 , . . . , n N R where a ( 0 ) = c ( 0 ) = 0 . Then
w = 1 s ϑ = 1 n a w c ϑ l w r 1 + r ϑ l 1 D ( l , r , s , n ) w = 1 s ( s w + 1 ) a w r 1 r × ϑ = 1 n ( n ϑ + 1 ) c ϑ l 1 l .
Here, a w = a w a w 1 , c ϑ = c ϑ c ϑ 1 and
D ( l , r , s , n ) = 1 l r s r 1 r n l 1 l .
Moreover, if l , r > 1 with 1 / l + 1 / r = 1 , f ( w ) and g ( ϑ ) are real-valued continuous functions with f ( 0 ) = g ( 0 ) = 0 , then
0 η 0 τ f ( w ) g ( ϑ ) l w r 1 + r ϑ l 1 d w d ϑ M ( l , r , η , τ ) 0 η η w f ( w ) r d w 1 r × 0 τ τ ϑ g ( ϑ ) l d ϑ 1 l .
Here,
M ( l , r , η , τ ) = 1 l r η r 1 r τ l 1 l .
In [7], Chang-Jian et al. established a set of new inequalities that are similar to extensions of Hilbert’s double-series inequality and derived their integral analogues. These inequalities are outlined as follows: let r j > 1 such that 1 / l j + 1 / r j = 1 and a j ( w j ) are real sequences defined for w j = 0 , 1 , 2 , . . . , s j where s j N and a j 0 = 0 ; j = 1 , 2 , . . . , n . Define the operator ∇ as a j ( w j ) = a j ( w j ) a j ( w j 1 ) . Then
w 1 = 1 s 1 w 2 = 1 s 2 . . . w n = 1 s n j = 1 n a j ( w j ) j = 1 n w j l j j = 1 n 1 l j K j = 1 n w j = 1 s j s j w j + 1 Δ a j ( w j ) r j 1 r j .
Here,
K = n j = 1 n 1 r j j = 1 n 1 r j n j = 1 n s j 1 l j .
Also, they proved that if h j 1 , l j , r j > 1 are constants with 1 / r j + 1 / l j = 1 , f j ( w j ) are real valued differentiable functions defined on [ 0 , η j ) where η j 0 , and f j 0 = 0 ; j = 1 , 2 , . . . , n , then
0 η 1 . . . 0 η n j = 1 n f j h j ( w j ) j = 1 n w j l j j = 1 n 1 l j d w n . . . d w 1 L j = 1 n 0 η j η j w j f j h j 1 ( w j ) . f j ( w j ) r j d w j 1 r j ,
where
L = n j = 1 n 1 r j j = 1 n 1 r j n j = 1 n h j η j 1 l j .
Furthermore, they established that if l j , r j > 1 such that 1 / r j + 1 / l j = 1 , a j ( w j , z j ) be real sequences defined for w j , z j where w j = 0 , 1 , 2 , . . . , s j , z j = 0 , 1 , 2 , . . . , n j ; s j , n j N and a j ( 0 , z j ) = a j ( w j , 0 ) = 0 j = 1 , 2 , . . . , n . Define the operators 1 and 2 by
1 a j ( w j , z j ) = a j ( w j , z j ) a j ( w j 1 , z j ) ,
2 a j ( w j , z j ) = a j ( w j , z j ) a j ( w j , z j 1 ) .
Then
w 1 = 1 s 1 z 1 = 1 t 1 . . . w n = 1 s n z n = 1 t n j = 1 n a j ( w j , z j ) j = 1 n w j z j / l j j = 1 n 1 l j R j = 1 n w j = 1 s j z j = 1 t j s j w j + 1 t j z j + 1 2 1 a j ( w j , z j ) r j 1 r j .
Here,
R = n j = 1 n 1 r j j = 1 n 1 r j n . j = 1 n s j n j 1 l j .
In recent decades, a novel theory known as time scale theory has emerged, aimed at unifying continuous calculus and discrete calculus. The results presented in this paper encompass classical continuous and discrete inequalities as special cases when T = R and T = N , respectively. Moreover, these inequalities can be extended to analogous inequalities on various time scales, such as T = q Z for q > 1 . Many researchers have delved into dynamic inequalities on time scales, and for a more comprehensive understanding of these dynamic inequalities on time scales, readers are referred to the following papers: [3,4,12,15,16,19,20,21].
The primary objective of this paper is to establish analogous formulas for Hilbert-type inequalities (7), (9) and (8) within the framework of time scales in delta calculus. It’s important to note that these formulas are derived under specific conditions, which are a j ( s j ) = 0 and a j ( s j , z j ) = a j ( w j , n j ) = 0 j = 1 , 2 , . . . , n . These conditions differ from those utilized in a previous work [7]. The outcomes of our research provide novel insights and estimations for these specific categories of inequalities. In particular, we have introduced multivariate summation inequalities for extensions of the Hilbert inequality, which were previously unproven. Additionally, we have obtained their corresponding integral expressions. The proofs of these results are based on the application of Hölder’s inequality on time scales and the mean inequality.
The paper is structured as follows: After this introductory section, the subsequent section offers an overview of fundamental concepts in time scale calculus, which serve as the basis for our proofs. The final section is dedicated to presenting our main findings.

2. Basic Principles

In what follows, the time scale T is a nonempty closed subset of R , and it could be an interval, a union of intervals, or even a set of isolated points. The real numbers (continuous case), integers (discrete case), and various amalgamations of the two constitute the most prevalent instances of time scales. Given ν T , we establish σ : T T and μ : T R as σ ( ν ) : = inf { α T : α > ν } and μ ( ν ) : = σ ( ν ) ν 0 . These components are referred to as the forward jump operator and the forward graininess function, correspondingly. Considering a function : T R , we introduce the notation:
σ ( ν ) = ( σ ( ν ) ) ν T .
Additionally, we establish the interval within the context of T as:
T : = T R .
Now, let’s examine a function : T R and we introduce the concept of the "delta derivative" or " Δ differentiable" of at a point v T as follows.
Definition 1 
([5]). We use the term "Δ differentiable" to describe a function ℑ being differentiable at v T , if ε > 0 there is a neighborhood W of v such that for some β the inequality
| ( σ ( v ) ) ( w ) β ( σ ( v ) w ) | ε | σ ( v ) w | , w W
is true and in this case we write Δ ( v ) = β .
Theorem 1 
(Properties of delta-derivatives [5]). Assume ℑ is a function and let v T k , then
1. 
If ℑ is differentiable at v, then ℑ is continuous at v.
2. 
If ℑ is continuous at v and v is right-scattered (i.e σ ( v ) > v ) , then ℑ is differentiable at v with
Δ ( v ) = ( σ ( v ) ) ( v ) μ ( v ) .
3. 
If v is right-dense (i.e σ ( v ) = v ) , then ℑ is differentiable iff the limit
lim w v ( v ) ( w ) v w ,
exists as a finite number. In this case
Δ ( v ) = lim w v ( v ) ( w ) v w .
Example 1. 
1. If T = R , then σ ( v ) = v , μ ( v ) = 0 and
Δ ( v ) = lim w v ( v ) ( w ) v w = ( v ) v T ,
where is the usual derivative.
2. If T = Z , then σ ( v ) = v + 1 , μ ( v ) = 1 and
Δ ( v ) = ( σ ( ) ) ( v ) μ ( v ) = ( v + 1 ) ( v ) = Δ ( v ) ,
where Δ is the usual forward difference operator.
3. If T = q Z : = { v : v = q k , k Z , q > 1 } { 0 } , then σ ( v ) = q v , μ ( v ) = ( q 1 ) v and
Δ ( v ) = Δ q ( v ) = ( q v ) ( v ) ( q 1 ) v v T { 0 } .
Theorem 2 
(Chain Rule [5]). Given that Υ : T R is a continuous and Δ differentiable and : R R is continuously differentiable, then
Υ Δ ( v ) = Υ ( τ ) Υ Δ ( v ) for τ [ v , σ ( v ) ] .
Definition 2 
([5]). A function ℑ is characterized as r d continuous when it exhibits continuity at every right-dense point within T and possesses finite left-sided limits at left-dense points in T . We use the symbol C r d ( T , R ) to represent the sets of all rd-continuous functions and the symbol C ( T , R ) to represent the set of all continuous functions.
Following is a description of the concept of an integral on time scales.
Definition 3 
([5]). ℜ is Δ antiderivative of ℑ if
Δ ( v ) = ( v ) holds v T k .
As a result, for a , c T , we deduce the integral of ℑ as
a c ( v ) Δ v = ( c ) ( a ) .
It’s widely acknowledged that any rd-continuous function possesses an antiderivative. As a result, we can deduce the following outcomes.
Theorem 3 
([5]). If v 0 , v T , then
v 0 v ( ϑ ) Δ ϑ Δ = ( v ) .
Theorem 4 
([5]). If a , c , τ T , α , β R and , Υ C r d ( [ a , c ] T , R ) , then
1. 
a c α ( δ ) + β Υ ( δ ) Δ δ = α a c ( δ ) Δ δ + β a c Υ ( δ ) Δ δ ;
2. 
a a ( δ ) Δ δ = 0 ;
3. 
a c ( δ ) Δ δ = a τ ( δ ) Δ δ + τ c ( δ ) Δ δ ;
4. 
If ( δ ) 0 ; δ [ a , c ] T , then a c ( δ ) Δ δ 0 .
5. 
a c ( δ ) Δ δ a c ( δ ) Δ δ .
Lemma 1 
(Integration by Parts [1]). If a , c T and ω , κ C r d ( [ a , c ] T , R ) , then
a c ω ( δ ) κ Δ ( δ ) Δ δ = ω ( δ ) κ ( δ ) a c a c ω Δ ( δ ) κ σ ( δ ) Δ δ .
Theorem 5 
([1]). Let a , c T and C r d ( T , R ) . Then
( j ) If T = R , then
a c ( δ ) Δ δ = a c ( δ ) d δ .
( j j ) If T = Z , then
a c ( δ ) Δ δ = δ = a c 1 ( δ ) .
( j j j ) If T = q Z , then
a c ( δ ) Δ δ = ( q 1 ) k = log q a log q c 1 q k ( q k ) .
Lemma 2 
(Hölder’s Inequality [1]). If a , c T and , Υ C r d ( [ a , c ] T , R + ) , then
a c ( δ ) Υ ( δ ) Δ δ a c ω ( δ ) η ( δ ) Δ δ 1 η a c ω ( δ ) Υ λ ( δ ) Δ δ 1 λ ,
where η > 1 and 1 / η + 1 / λ = 1 .
Next, we present the Hölder’s inequality in two dimensions on time scales.
Let T 1 , T 2 be time scales, C C r d denote the set of functions τ , ξ on T 1 × T 2 , where is r d continuous in τ , ξ and C C r d denote the set of all functions C C r d for which both the Δ 1 partial derivative with respect to τ and Δ 2 partial derivative with respect to ξ exist and are in C C r d .
Lemma 3 
([18], Theorem 3.3). Let η , λ T with η < λ , f , g C C r d ( η , λ T × η , λ T , R ) and γ , ν > 1 such that 1 / γ + 1 / ν = 1 . Then
η λ η λ | f ( τ , ξ ) g ( τ , ξ ) | Δ 1 τ Δ 2 ξ η λ η λ | f ( τ , ξ ) | γ Δ 1 τ Δ 2 ξ 1 γ η λ η λ | g ( τ , ξ ) | ν Δ 1 τ Δ 2 ξ 1 ν .
Lemma 4 
(Fubini’s theorem [6]). If η , λ , c , d T and C C r d η , λ T × c , d T , R is Δ integrable, then
η λ c d ( τ , ξ ) Δ 2 ξ Δ 1 τ = c d η λ ( τ , ξ ) Δ 1 τ Δ 2 ξ .
Lemma 5 
(Mean inequality [9]). If α j , β j > 0 for j = 1 , 2 , . . . , s , then
j = 1 s α j β j j = 1 s α j β j j = 1 s β j j = 1 s β j j = 1 s β j .

3. Main Results

Throughout this paper, we will operate under the assumption that the functions are rd-continuous and we will also consider the existence of the integrals. To substantiate our results, it is necessary to prove the following lemma.
Lemma 6. 
Let l j , r j > 1 with 1 / l j + 1 / r j = 1 and w j > 0 , where j = 1 , 2 , . . . , n . Then
j = 1 n w j 1 l j j = 1 n w j l j j = 1 m 1 l j s j = 1 s 1 r j s j = 1 s 1 r j .
Proof. 
By utilizing Lemma 5 with α j = w j and β j = 1 / l j , we deduce that
j = 1 s w j 1 l j j = 1 s w j l j j = 1 s 1 l j j = 1 s 1 l j j = 1 s 1 l j .
Since j = 1 s ( 1 / l j ) = j = 1 s 1 ( 1 / r j ) = s j = 1 s ( 1 / r j ) , then (17) becomes
j = 1 s w j 1 l j j = 1 s w j l j j = 1 s 1 l j s j = 1 s 1 r j s j = 1 s 1 r j ,
which is (16). □
Theorem 6. 
Let a j , ε j T , l j , r j > 1 such that 1 / l j + 1 / r j = 1 and λ j C r d ( a j , ε j T , R ) with λ j ( ε j ) = 0 ; j = 1 , 2 , . . . , s . Then
a s ε s . . . a 1 ε 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j Δ ξ 1 . . . Δ ξ s A j = 1 s a j ε j σ ( ξ j ) a j λ j Δ ( ξ j ) r j Δ ξ j 1 r j ,
where
A = s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ε j a j 1 l j .
Proof. 
By utilizing the property (5) of Theorem 4 and using the assumption λ j ( ε j ) = 0 , we deduce that
ξ j ε j λ j Δ ( z j ) Δ z j ξ j ε j λ j Δ ( z j ) Δ z j = λ j ( ε j ) λ j ( ξ j ) = λ j ( ξ j )
and then
j = 1 s λ j ( ξ j ) j = 1 s ξ j ε j λ j Δ ( z j ) Δ z j .
Applying (13) on ξ j ε j λ j Δ ( z j ) Δ z j with l j , r j > 1 , ( z j ) = λ j Δ ( z j ) and Υ ( z j ) = 1 , we have
ξ j ε j λ j Δ ( z j ) Δ z j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j ξ j ε j Δ z j 1 l j = ε j ξ j 1 l j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j
and then
j = 1 s ξ j ε j λ j Δ ( z j ) Δ z j j = 1 s ε j ξ j 1 l j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j = j = 1 s ε j ξ j 1 l j j = 1 s ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j .
By substituting (21) into (20) and applying (16) on j = 1 s ε j ξ j ( 1 / l j ) with w j = ε j ξ j , we acquire
j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j 1 l j j = 1 s ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j j = 1 s ε j ξ j l j j = 1 s 1 l j s j = 1 s 1 r j s j = 1 s 1 r j j = 1 s ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j .
Dividing (22) on j = 1 s ε j ξ j l j j = 1 s 1 l j and integrating over ξ j from a j to ε j , j = 1 , 2 , . . . , s , we conclude that
a s ε s . . . a 1 ε 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j Δ ξ 1 . . . Δ ξ s s j = 1 s 1 r j j = 1 s 1 r j s a s ε s . . . a 1 ε 1 j = 1 s ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j Δ ξ 1 . . . Δ ξ s = s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j Δ ξ j .
Again, using (13) on a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j Δ ξ j with l j , r j > 1 , ξ j = ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j and Υ ξ j = 1 , we get
a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j Δ ξ j a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j 1 r j a j ε j Δ ξ j 1 l j = ε j a j 1 l j a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j 1 r j ,
and then
j = 1 s a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j 1 r j Δ ξ j j = 1 s ε j a j 1 l j a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j 1 r j = j = 1 s ε j a j 1 l j j = 1 s a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j 1 r j .
Substituting (24) into (23), we obtain
a s ε s . . . a 1 ε 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j Δ ξ 1 . . . Δ ξ s s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ε j a j 1 l j j = 1 s a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j 1 r j .
Now, using (12) on a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j with ω ( ξ j ) = ξ j ε j λ j Δ ( z j ) r j Δ z j and κ Δ ( ξ j ) = 1 , we find that
a j ε j ξ j ε j λ j Δ ( z j ) r j Δ z j Δ ξ j = ξ j ε j λ j Δ ( z j ) r j Δ z j κ ( ξ j ) a j ε j + a j ε j λ j Δ ( ξ j ) r j κ σ ( ξ j ) Δ ξ j = a j ε j λ j Δ ( ξ j ) r j σ ( ξ j ) a j Δ ξ j ,
where κ ( ξ j ) = ξ j a j . Combining (26) with (25), we get
a s ε s . . . a 1 ε 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j Δ ξ 1 . . . Δ ξ s s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ε j a j 1 l j × j = 1 s a j ε j λ j Δ ( ξ j ) r j σ ( ξ j ) a j Δ ξ j 1 r j = A j = 1 s a j ε j λ j Δ ( ξ j ) r j σ ( ξ j ) a j Δ ξ j 1 r j .
Hence, (22) is proved. □
Corollary 1. 
Let T = Z in Theorem 6, a j , ε j N , l j , r j > 1 such that 1 / r j + 1 / l j = 1 and λ j be real sequences with λ j ( ε j ) = 0 ; j = 1 , 2 , . . . , s . Then σ ( ξ j ) = ξ j + 1 and
ξ 1 = a 1 ε 1 1 ξ 2 = a 2 ε 2 1 . . . ξ s = a s ε s 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j A j = 1 s ξ j = a j ε j 1 ξ j a j + 1 Δ λ j ( ξ j ) r j 1 r j .
Here, Δ is the forward difference operator and A is specified as in (19).
Corollary 2. 
Let T = R in Theorem 6, a j , ε j R , l j , r j > 1 such that 1 / r j + 1 / l j = 1 and λ j C ( a j , ε j , R ) with λ j ( ε j ) = 0 ; j = 1 , 2 , . . . , s . Then σ ( ξ j ) = ξ j and
a s ε s . . . a 1 ε 1 j = 1 s λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j d ξ 1 . . . d ξ s A j = 1 s a j ε j λ j ( ξ j ) r j ξ j a j d ξ j 1 r j ,
where A is given by (19).
Corollary 3. 
Let T = q Z for q > 1 , l j , r j > 1 such that 1 / r j + 1 / l j = 1 and λ j be real sequences with λ j ( ε j ) = 0 ; j = 1 , 2 , . . . , s . Then σ ( ξ j ) = q ξ j and
ξ s = log q a s log q ε s 1 . . . ξ 1 = log q a 1 log q ε 1 1 ( q 1 ) n j = 1 s ξ j λ j ( ξ j ) j = 1 s ε j ξ j l j j = 1 s 1 l j A j = 1 s ξ j = log q a j log q ε j 1 ( q 1 ) q ξ j a j ξ j Δ q λ j ( ξ j ) r j 1 r j ,
where A is given by (19) and
Δ q λ j ( ξ j ) = λ j ( q ξ j ) λ j ξ j q 1 ξ j ξ j T { 0 } .
In the following, we generalize the last theorem for two variables.
Theorem 7. 
Let a j , ε j , ϵ j T , l j , r j > 1 such that 1 / l j + 1 / r j = 1 , λ j C C r d ( a j , ε j T × a j , ϵ j T , R ) with λ j ( τ j , ε j ) = λ j ( ϵ j , ξ j ) = 0 for ξ j a j , ε j T and τ j a j , ϵ j T ; j = 1 , 2 , . . . , s . Then
a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j Δ 2 ξ 1 . . . Δ 2 ξ s Δ 1 τ 1 . . . Δ 1 τ s B j = 1 s a j ϵ j a j ε j σ τ j a j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j Δ 1 τ j 1 r j ,
where
B = s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ϵ j a j 1 l j ε j a j 1 l j .
Here, the Δ 1 derivative of λ ( τ , ξ ) is the Δ derivative with respect to the first variable τ and the Δ 2 derivative of λ ( τ , ξ ) is the Δ derivative with respect to the second variable ξ .
Proof. 
Applying the property (5) of Theorem 4, Fubini’s theorem and using the hypothesis λ j ( τ j , ε j ) = λ j ( ϵ j , ξ j ) = 0 , we get
τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( t j , ϑ j ) Δ 2 ϑ j Δ 1 z j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) Δ 2 ϑ j Δ 1 z j = τ j ϵ j ξ j ε j λ j Δ 2 ( z j , ϑ j ) Δ 1 Δ 2 ϑ j Δ 1 z j = ξ j ε j τ j ϵ j λ j Δ 2 ( z j , ϑ j ) Δ 1 Δ 1 z j Δ 2 ϑ j = ξ j ε j λ j Δ 2 ( ϵ j , ϑ j ) λ j Δ 2 ( τ j , ϑ j ) Δ 2 ϑ j = λ j ( ϵ j , ε j ) λ j ( ϵ j , ξ j ) + λ j ( τ j , ξ j ) λ j ( τ j , ε j ) = λ j ( τ j , ξ j ) ,
and then
j = 1 s λ j ( τ j , ξ j ) j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) Δ 2 ϑ j Δ 1 z j .
Applying (14) on τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) Δ 2 ϑ j Δ 1 z j with l j , r j > 1 , f ( z j , ϑ j ) = 1 and g ( z j , ϑ j ) = λ j Δ 2 Δ 1 ( z j , ϑ j ) , we see that
τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) Δ 2 ϑ j Δ 1 z j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j τ j ϵ j ξ j ε j Δ 2 ϑ j Δ 1 z j 1 l j = ϵ j τ j 1 l j ε j ξ j 1 l j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j ,
and then
j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) Δ 2 ϑ j Δ 1 z j j = 1 s ϵ j τ j 1 l j ε j ξ j 1 l j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j = j = 1 s ϵ j τ j 1 l j ε j ξ j 1 l j j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j .
Substituting (30) into (29) and applying (16) on w j = ϵ j τ j ε j ξ j , we obtain
j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j 1 l j ε j ξ j 1 l j j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j s j = 1 s 1 r j s j = 1 s 1 r j j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j .
Dividing (31) on j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j , integrating over ξ j from a j to ε j and over τ j from a j to ϵ j for j = 1 , 2 , . . . , s , we conclude that
a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j Δ 2 ξ 1 . . . Δ 2 ξ s Δ 1 τ 1 . . . Δ 1 τ s s j = 1 s 1 r j j = 1 s 1 r j s × a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j Δ 2 ξ 1 . . . Δ 2 ξ s Δ 1 τ 1 . . . Δ 1 τ s = s j = 1 s 1 r j j = 1 s 1 r j s × j = 1 s a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j Δ 2 ξ j Δ 1 τ j .
Again, using (14) on a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j Δ 2 ξ j Δ 1 τ j with exponents r j , l j > 1 and f ( ξ j , τ j ) = 1 ,
g ( ξ j , τ j ) = τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j ,
we observe that
a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j Δ 2 ξ j Δ 1 τ j a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 2 ξ j Δ 1 τ j 1 r j a j ϵ j a j ε j Δ 2 ξ j Δ 1 τ j 1 l j = ϵ j a j 1 l j ε j a j 1 l j a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 2 ξ j Δ 1 τ j 1 r j ,
and then
j = 1 s a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j 1 r j Δ 2 ξ j Δ 1 τ j j = 1 s ϵ j a j 1 l j ε j a j 1 l j a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 2 ξ j Δ 1 τ j 1 r j = j = 1 s ϵ j a j 1 l j ε j a j 1 l j × j = 1 s a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 2 ξ j Δ 1 τ j 1 r j .
Substituting (33) into (32) and applying the Fubini theorem, we see that
a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j Δ 2 ξ 1 . . . Δ 2 ξ s Δ 1 τ 1 . . . Δ 1 τ s s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ϵ j a j 1 l j ε j a j 1 l j × j = 1 s a j ϵ j a j ε j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 2 ξ j Δ 1 τ j 1 r j = s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ϵ j a j 1 l j ε j a j 1 l j × j = 1 s a j ε j a j ϵ j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 1 τ j Δ 2 ξ j 1 r j .
Now, by applying (12) on a j ϵ j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 1 τ j with
ω ( τ j ) = τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j and κ Δ ( τ j ) = 1 ,
we find that
a j ϵ j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 1 τ j = κ ( τ j ) τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j a j ϵ j + a j ϵ j κ σ ( τ j ) ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 1 τ j = a j ϵ j σ τ j a j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 1 τ j .
where κ ( τ j ) = τ j a j . By integrating (34) over ξ j from a j to ε j and using the Fubini theorem, we have
a j ε j a j ϵ j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 1 τ j Δ 2 ξ j = a j ε j a j ϵ j σ τ j a j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 1 τ j Δ 2 ξ j = a j ϵ j a j ε j σ τ j a j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 2 ξ j Δ 1 τ j = a j ϵ j σ τ j a j a j ε j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 2 ξ j Δ 1 τ j .
Again, using (12) on the term a j ε j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 2 ξ j with
ω ( τ j ) = ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j and κ Δ ξ j = 1 ,
we see that
a j ε j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j Δ 2 ξ j = κ ξ j ξ j ε j λ j Δ 2 Δ 1 ( τ j , ϑ j ) r j Δ 2 ϑ j a j ε j + a j ε j κ σ ξ j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j = a j ε j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j .
where κ ξ j = ξ j a j . Substituting (37) into (36) and applying Fubini’s theorem, we obtain
a j ε j a j ϵ j τ j ϵ j ξ j ε j λ j Δ 2 Δ 1 ( z j , ϑ j ) r j Δ 2 ϑ j Δ 1 z j Δ 1 τ j Δ 2 ξ j = a j ϵ j σ τ j a j a j ε j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j Δ 1 τ j = a j ϵ j a j ε j σ τ j a j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j Δ 1 τ j = a j ε j a j ϵ j σ τ j a j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 1 τ j Δ 2 ξ j .
Substituting (38) into (34), we get
a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j Δ 2 ξ 1 . . . Δ 2 ξ s Δ 1 τ 1 . . . Δ 1 τ s s j = 1 s 1 r j j = 1 s 1 r j s j = 1 s ϵ j a j 1 l j ε j a j 1 l j × j = 1 s a j ε j a j ϵ j σ τ j a j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j Δ 1 τ j 1 r j = B j = 1 s a j ε j a j ϵ j σ τ j a j σ ξ j a j λ j Δ 2 Δ 1 ( τ j , ξ j ) r j Δ 2 ξ j Δ 1 τ j 1 r j .
Hence, (27) is proved. □
Corollary 4. 
Let T = Z in Theorem 7, a j , ε j , ϵ j Z , r j , l j > 1 such that 1 / r j + 1 / l j = 1 and λ j be real sequenceswith λ j ( τ j , ε j ) = λ j ( ϵ j , ξ j ) = 0 for ξ j a j , ε j and τ j a j , ϵ j , where j = 1 , 2 , . . . , s . Then σ τ j = τ j + 1 , σ ξ j = ξ j + 1 and
τ s = a s ϵ s 1 τ 1 = a 1 ϵ 1 1 . . . ξ s = a s ε s 1 ξ 1 = a 1 ε 1 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j B j = 1 s ξ j = a j ε j 1 τ j = a j ϵ j 1 τ j a j + 1 ξ j a j + 1 Δ 2 Δ 1 λ j ( τ j , ξ j ) r j 1 r j ,
where B is given by (28).
Corollary 5. 
Let T = R in Theorem 7, a j , ε j , ϵ j R , r j , l j > 1 such that 1 / r j + 1 / l j = 1 and λ j C C ( a j , ε j × a j , ϵ j , R ) with λ j ( τ j , ε j ) = λ j ( ϵ j , ξ j ) = 0 for ξ j a j , ε j T and τ j a j , ϵ j T , where j = 1 , 2 , . . . , s . Then σ τ j = τ j , σ ξ j = ξ j and
a s ϵ s a 1 ϵ 1 . . . a s ε s a 1 ε 1 j = 1 s λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j d ξ 1 . . . d ξ s d τ 1 . . . d τ s B j = 1 s a j ε j a j ϵ j τ j a j ξ j a j 2 λ j ( τ j , ξ j ) ξ j τ j r j d ξ j d τ j 1 r j ,
where B is given by (28).
Corollary 6. 
Let T = q Z for q > 1 , a j , ε j , ϵ j T , r j , l j > 1 such that 1 / r j + 1 / l j = 1 and λ j are real sequences with λ j ( τ j , ε j ) = λ j ( ϵ j , ξ j ) = 0 for ξ j a j , ε j and τ j a j , ϵ j , where j = 1 , 2 , . . . , s . Then σ τ j = q τ j , σ ξ j = q ξ j and
τ s = log q a s log q ϵ s 1 τ 1 = log q a 1 log q ϵ 1 1 . . . ξ s = log q a s log q ε s 1 ξ 1 = log q a 1 log q ε 1 1 ( q 1 ) 2 n j = 1 s τ j ξ j λ j ( τ j , ξ j ) j = 1 s ϵ j τ j ( ε j ξ j ) l j j = 1 s 1 l j B j = 1 s τ j = log q a j log q ϵ j 1 ξ j = log q a j log q ε j 1 q τ j a j q ξ j a j ( q 1 ) 2 τ j ξ j Δ q 2 Δ q 1 λ j ( τ j , ξ j ) r j 1 r j .
Here B is given by (28) and the Δ q 1 derivative of λ ( τ , ξ ) is the Δ q derivative with respect to the first variable τ and the Δ q 2 derivative of λ ( τ , ξ ) is the Δ q derivative with respect to the second variable ξ .

4. Conclusions

In this study, a generalization of the Hilbert-type inequalities within the framework of time scales in delta calculus. We should note that we used different conditions from some previous results, thus, various refinements of the classic Hilbert-type inequalities are obtained. Throughout the work, it is shown that some known results from the literature are obtained as particular cases of ours. For future work, we will be able to present such inequalities by employing nabla calculus and diamond- α calculus for α ( 0 , 1 ) . Additionally, it will be very fascinating to present similar inequalities on time scales using Riemann–Liouville type fractional integrals.

Author Contributions

Investigation, Software and Writing—original draft H.M.R. and A.I.S.; Supervision, Writing—review editing and Funding, J.E.N.V., M.A. and M.Z. All authors have read and agreed to the published version of the manuscript.

Acknowledgments

The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project under grant number RGP 2/414/44.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. R. P. Agarwal, D. O’Regan and S. H. Saker, Dynamic Inequalities on Time Scales, Springer Cham Heidlelberg New York Dordrechet London 2014.
  2. G. AlNemer, A. I. Saied, M. Zakarya, H. A. Abd El-Hamid, O. Bazighifan and H. M. Rezk, Some New Reverse Hilbert’s Inequalities on Time Scales. Symmetry, 13(12), 2431, (2021). [CrossRef]
  3. R. Bibi, M. Bohner, J. Pečarić and S. Varošanec, Minkowski and Beckenbach-Dresher inequalities and functionals on time scales, J. Math. Inequal 7(3) (2013), 299-312.
  4. M. Bohner and S. G. Georgiev, Multiple integration on time scales. Multivariable dynamic calculus on time scales. Springer, Cham (2016), 449-515.
  5. M. Bohner and A. Peterson, Dynamic Equations on Time Scales: An introduction with applications. Birkhäuser, Boston, Mass, the USA, 2001.
  6. M. Bohner and G. S. Guseinov, Multiple integration on time scales. Dyn.Syst. Appl. 14, (2005), 579-606.
  7. Z. Chang-Jian, C. Lian-Ying and W. S. Cheung, On some new Hilbert-type inequalities. Mathematica Slovaca, 61(1), (2011), 15-28. [CrossRef]
  8. G. H. Hardy, Note on a theorem of Hilbert concerning series of positive term, Proc. London Math. Soc. 23, (1925), 45-46. [CrossRef]
  9. G. H. Hardy, J. E. Littlewood and G. Pólya, Inequalities. Cambridge university press, (1952).
  10. D. Hilbert, Grundzüge einer allgemeinen theorie der linearen intergraleichungen, Göttingen Nachr. (1906), 157-227.
  11. Y. H. Kim and B. I. Kim, An Analogue of Hilberts inequality and its extensions. Bull. Korean Math. Soc. (2002), 39, 377–388.
  12. J. A. Oguntuase and L. E. Persson, Time scales Hardy-type inequalities via superquadracity. Annals of Functional Analysis, 5(2) (2014), 61-73. [CrossRef]
  13. B. G. Pachpatte, A note on Hilbert type inequality. Tamkang J. Math. (1998), 29, 293–298.
  14. B. G. Pachpatte, Inequalities Similar to Certain Extensions of Hilbert’s Inequality. J. Math. Anal. Appl. (2000), 243, 217–227. [CrossRef]
  15. P. Řehak, Hardy inequality on time scales and its application to half-linear dynamic equations. Journal of Inequalities and Applications, 2005(5) (2005), 495-507. [CrossRef]
  16. H. M. Rezk, G. AlNemer, A. I. Saied, O. Bazighifan and M. Zakarya, Some New Generalizations of Reverse Hilbert-Type Inequalities on Time Scales. Symmetry, 14(4), 750, (2022).
  17. I. Schur, Bernerkungen sur theorie der beschrankten Bilinearformen mit unendlich vielen veranderlichen, Journal of Mathematics 140, (1911), 1-28. [CrossRef]
  18. A. Tuna and S. Kutukcu, Some integral inequalities on time scales. Applied Mathematics and Mechanics, 29(1), (2008), 23-29. [CrossRef]
  19. M. Zakarya, G. AlNemer, A. I. Saied, R. Butush, O. Bazighifan and H. M. Rezk, Generalized Inequalities of Hilbert-Type on Time Scales Nabla Calculus. Symmetry, 14(8), 1512, (2022). [CrossRef]
  20. M. Zakarya, A. I. Saied, G. ALNemer, H. A. Abd El-Hamid and H. M. Rezk, A study on some new generalizations of reversed dynamic inequalities of Hilbert-type via supermultiplicative functions. Journal of function spaces, 2022, (2022). [CrossRef]
  21. M. Zakarya, A. I. Saied, G. AlNemer and H. M. Rezk, A study on some new reverse Hilbert-type inequalities and its generalizations on time scales. Journal of mathematics, 2022, (2022). [CrossRef]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.
Copyright: This open access article is published under a Creative Commons CC BY 4.0 license, which permit the free download, distribution, and reuse, provided that the author and preprint are cited in any reuse.
Prerpints.org logo

Preprints.org is a free preprint server supported by MDPI in Basel, Switzerland.

Subscribe

© 2024 MDPI (Basel, Switzerland) unless otherwise stated