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Article

Gamma-Nabla Hardy–Hilbert-Type Inequalities on Time Scales

by
Barakah Almarri
1,* and
Ahmed A. El-Deeb
2,*
1
Department of Mathematical Sciences, College of Sciences, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
2
Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt
*
Authors to whom correspondence should be addressed.
Axioms 2023, 12(5), 449; https://doi.org/10.3390/axioms12050449
Submission received: 3 April 2023 / Revised: 21 April 2023 / Accepted: 26 April 2023 / Published: 1 May 2023
(This article belongs to the Special Issue 10th Anniversary of Axioms: Mathematical Analysis)

Abstract

:
We investigated several novel conformable fractional gamma-nabla dynamic Hardy–Hilbert inequalities on time scales in this study. Several continuous inequalities and their corresponding discrete analogues in the literature are combined and expanded by these inequalities. Hölder’s inequality on time scales and a few algebraic inequalities are used to demonstrate our findings.

1. Introduction

This is a statement of the well-known classical extension of Hilbert’s double-series theorem [1]:
Theorem 1.
If ν , ϖ > 1 are such that 1 ν + 1 ϖ 1 and 0 < λ = 2 1 ν 1 ϖ = 1 ν + 1 ϖ 1 , such that ν and ϖ present the exponents’ conjugate; then,
j = 1 i = 1 ϑ j π i ( j + i ) λ K j = 1 ϑ j ν 1 ν ( i = 1 π i ϖ ) 1 ϖ ,
where K = K ( ν , ϖ ) depends on ν and ϖ only.
Readers may find the integral analogue of Theorem 1 in [1].
Theorem 2.
Let ν , ϖ , ν , ϖ and λ be as in Theorem 1. If ϑ L ν ( 0 , ) and θ L ϖ ( 0 , ) , then
0 0 ϑ ( ι ) θ ( ς ) ( ι + ς ) λ d ι d ς K 0 ϑ ν ( ι ) d ι 1 ν 0 θ ϖ ( ς ) d ς 1 ϖ ,
where K = K ( ν , ϖ ) depends on ν and ϖ only.
In 2011, Zhao et al. [2] proposed a new inequality similar to Theorem 2.
Theorem 3.
Let h i 1 , ν i > 1 be constants and 1 ν i + 1 ϖ i = 1 . Let the differentiable fun. ϑ i ( i ) on [ 0 , ι i ) , where ι i ( 0 , ) , and we use ϑ i as a differentiation of ϑ i . Suppose ϑ i ( 0 ) = 0 for ( i = 1 , , n ) . Then,
0 ι 1 0 ι 2 0 ι n i = 1 n | ϑ i h i ( i ) | i = 1 n i ϖ i i = 1 n 1 ϖ i d n d n 1 d 1 K i = 1 n 0 ι i ( ι i i ) | ϑ i h i 1 ( i ) ϑ i ( i ) | ν i d i 1 ν i ,
where
K = n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n h i ι i 1 ϖ i .
Moreover, in 2012, Zhoa and Chung [3] proved the following theorem.
Theorem 4.
Let ν i > 1 , be constants and 1 ν i + 1 ϖ i = 1 . Let ϑ i ( τ 1 i , , τ n i ) be real-valued nth differentiable functions defined on [ 0 , ι 1 i ) × × [ 0 , ι n i ) , where 0 ι j i δ j i , δ j i ( 0 , ) and i , j = 1 , , n . Suppose
ϑ i ( ι 1 i , , ι n i ) = 0 ι 1 i 0 ι n i n τ 1 i τ n i ϑ i ( τ 1 i , , τ n i ) d τ n i d τ 1 i ,
then
0 δ 11 0 δ n 1 0 δ 12 0 δ n 2 0 δ 1 n 0 δ n n i = 1 n 0 ι 1 i 0 ι n i | n τ 1 i τ n i ϑ i ( τ 1 i , , τ n i ) | ν i d τ n i d τ 1 i 1 ν i i = 1 n ι 1 i ι n i ϖ i i = 1 n 1 ϖ i d ι 11 d ι n 1 d ι 12 d ι n 2 d ι 1 n d ι n n N i = 1 n 0 δ 1 i 0 δ n i j = 1 n ( δ j i ι j i ) | n ι 1 i ι n i ϑ i ( ι 1 i , , ι n i ) | ν i d ι n i d ι 1 i 1 ν i ,
where
N = n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n δ 1 i δ n i 1 ϖ i .
Pachappte [4] proved the following one:
m = 1 k n = 1 r Φ ( a m ) Ψ ( b n ) m + n M ( k , r ) ( m = 1 k ( k m + 1 ) p m Φ a m p m 2 1 2 ) × ( n = 1 r ( r n + 1 ) q n Ψ b n q n 2 1 2 ) ,
where
M ( k , r ) = 1 2 m = 1 k Φ ( P m ) p m 2 1 2 n = 1 r Ψ ( Q n ) Q n 2 1 2
0 ϑ 0 ς Φ ( ϝ ( s ) ) Ψ ( g ( ) ) s + d s d t L ( ϑ , ς ) ( 0 ϑ ( ϑ s ) p ( s ) Φ ϝ ( s ) p ( s ) 2 d s 1 2 ) × ( 0 ς ( ς ) q ( ) Ψ g ( ) q ( ) 2 d t 1 2 )
where
L ( ϑ , ς ) = 1 2 0 ϑ Φ ( P ( s ) ) P ( s ) 2 d s 1 2 0 ς Ψ ( Q ( ) ) Q ( ) 2 d t 1 2 .
Handley et al. [5] extended (4) and (5) as follows:
m 1 = 1 k 1 m n = 1 k n = 1 n Φ ( a , m ) = 1 n γ m γ M ( k 1 , , k n ) = 1 n ( m = 1 k ( k m + 1 ) p , m Φ a , m p , m 1 γ γ
where
M ( k 1 , , k n ) = 1 ( γ ) γ = 1 n m = 1 k Φ ( P , m ) P , m 1 γ γ ,
and
0 ϑ 1 0 ϑ n = 1 n Φ ( ϝ ( s ) ) = 1 n γ s γ d s 1 d s n L ( ϑ 1 , , ϑ n ) = 1 n ( 0 ϑ ( ϑ s ) p ( s ) Φ ϝ ( s ) p ( s ) 1 γ d s γ ,
where
L ( ϑ 1 , , ϑ n ) = 1 ( γ ) γ = 1 n 0 ϑ Φ ( P ( s ) ) P ( s ) 1 γ d s γ .
In 2006, Zhao and Cheung [6] proved the following reverse inequality.
0 ϑ 1 0 ς 1 0 ϑ n 0 ς n = 1 n Φ ( ϝ ( s , ) ) 1 γ = 1 n γ ( s ) γ d s 1 d 1 d s n d n G ( ϑ 1 ς 1 , , ϑ n y n ) × = 1 n 0 ϑ 0 ς ( ϑ s ) ( ς ) p ( s ) q ( ) Φ D 2 D 1 ϝ ( s , ) p ( s ) q ( ) 1 γ d s d γ
where
G ( ϑ 1 ς 1 , , ϑ n y n ) = = 1 n 0 ϑ 0 ς Φ ( P ( s , ) ) P ( s , ) 1 γ d s d γ .
and
P ( s , ) = 0 0 s p ( ξ ) q ( τ ) d ξ d τ .
In [7], Pachpatte studied the Hilbert version inequalities.
0 ϑ 0 ς ϝ h ( s ) G l ( ) s + d s d 1 2 h l ( x y ) 1 2 0 ϑ ( ϑ s ) ϝ h 1 ( s ) ϝ ( s ) 2 d s 1 2 × 0 ς ( ς ) G l 1 g ( ) 2 d 1 2 ,
and
0 ϑ 0 ς Φ ( ϝ ( s ) ) Ψ ( G ( ) ) s + d s d L ( ϑ , ς ) 0 ϑ ( ϑ s ) p ( s ) Φ ϝ ( s ) p ( s ) 2 d s 1 2 × 0 ς ( ς ) q ( ) Ψ g ( ) q ( ) 2 d 1 2
where
L ( ϑ , ς ) = 1 2 0 ϑ Φ ( P ( s ) ) P ( s ) 2 d s 1 2 0 ς Ψ ( Q ( ) ) Q ( ) 2 d 1 2 ,
and
0 ϑ 0 ς P ( s ) Q ( ) Φ ( ϝ ( s ) ) Ψ ( G ( ) ) s + d s d 1 2 ( x y ) 1 2 0 ϑ ( ϑ s ) p ( s ) Φ ϝ ( s ) 2 d s 1 2 × 0 ς ( ς ) q ( ) Ψ g ( ) 2 d 1 2 .
0 ϑ 1 0 ς 1 0 ϑ n 0 ς n = 1 n Φ ( ϝ ( s , ) ) γ = 1 n 1 γ ( s ) ( ) 1 γ d s 1 d 1 d s n d n L ( ϑ 1 ς 1 , , ϑ n y n ) × = 1 n 0 ϑ 0 ς ( ϑ s ) ( ς ) p ( s , ) Φ ϝ ( s , ) p ( s , ) β d s d 1 β .
where
L ( ϑ 1 ς 1 , , ϑ n y n ) = = 1 n 0 ϑ 0 ς Φ ( P ( s , ) ) P ( s , ) γ d s d 1 γ .
In [8,9,10], Yang et al. established some important extensions of a Hardy–Hilbert-type inequality by using the weight coefficient method and techniques of real analysis.
All of the aforementioned findings hold true for both continuous and discrete domains. The purpose of the current research is to provide new, more general conclusions to the time-scale-based disparities previously established. Supreme outcomes, from which many other previous and current results may be taken, would be produced in this way. See the following publications for various dynamic inequalities, integrals of Hilbert’s kind, and other categories of inequalities on time scales [11,12,13,14,15,16,17,18,19,20,21,22,23].
We hope that the reader has a sufficient background on the nabla conformable fractional on time scales. S. Hilger [24] introduced the time scale theory in 1988 as a way to combine continuous and discrete analysis. A time scale T is an arbitrary nonempty closed subset of the set of real numbers R . In the manuscript, we use the notation ( γ , a ) for the nabla conformable fractional derivative on time scales instead of a γ for simplification. For more details on nabla conformable fractionals, please see [25].
Definition 1 (Conformable nabla derivative).
Given a function f : T R and a T , f is ( γ , a ) -nabla differentiable at ξ > a , if it is nabla differentiable at ξ, and its ( γ , a ) -nabla derivative is defined by
a γ f ( ξ ) = G ^ 1 γ ( ξ , a ) f ( ξ ) ξ > a ,
Definition 2 (Conformable nabla integral).
Assume that 0 < γ 1 , a , ξ 1 , ξ 2 T , a ξ 1 ξ 2 and f C l d ( T ) , and the function f is called ( γ , a ) -nabla integrable on [ ξ 1 , ξ 2 ] if
a γ f ( ξ ) = ξ 1 ξ 2 f ( ξ ) a γ ξ = ξ 1 ξ 2 f ( ξ ) G ^ γ 1 ( σ γ 1 ( ξ ) , a ) ξ ,
exists and is finite.
Lemma 1
(Dynamic Hölder’s Inequality [14]). Let u , v T with u < v . If ϑ , θ C C r d 1 ( [ u , v ] T × [ u , v ] T , R ) be integrable functions and 1 ν + 1 ϖ = 1 with ν > 1 . Then,
u v u v | ϑ ( r , δ ) θ ( r , δ ) | ( γ , a ) r ( γ , a ) δ u v u v | ϑ ( r , δ ) | ν ( γ , a ) r ( γ , a ) δ 1 ν × u v u v | θ ( r , δ ) | ϖ ( γ , a ) r ( γ , a ) δ 1 ϖ .
This inequality is reversed if 0 < ν < 1 and if ν < 0 or ϖ < 0 .
In this study, we prove a few novel conformable fractional dynamic inequalities of the Hardy–Hilbert type on time scales, which are driven by Theorems 3 and 4 given above. We will also extract the discrete counterparts of the continuous Hilbert inequalities that are present in some special situations of our results. We are now prepared to state and support our key findings.

2. Main Results

Theorem 5.
Let T be a time scale with δ 0 , ι i , i , δ i T , ( i = 1 , , n ) . Let h i 1 , ν i , ϖ i > 1 be constants and 1 ν i + 1 ϖ i = 1 . Let ( γ , a ) - differentiable functions ϑ i ( i ) be decreasing on [ δ 0 , ι i ) T , where ι i ( 0 , ) . Suppose ϑ i ( δ 0 ) = 0 . Then,
δ 0 ι 1 δ 0 ι 2 δ 0 ι n i = 1 n | ϑ i h i ( i ) | i = 1 n ( i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) n ( γ , a ) n 1 ( γ , a ) 1 K i = 1 n δ 0 ι i ( ρ ( ι i ) ρ ( i ) ) | ϑ i h i 1 ( i ) ϑ i ( γ , a ) ( i ) | ν i ( γ , a ) i 1 ν i ,
where
K = K ( ι 1 , , ι n ) = n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n h i ( ι i δ 0 ) 1 ϖ i .
Proof. 
From Hölder inequality (16), one can see that
i = 1 n | ϑ i h i ( i ) | i = 1 n h i δ 0 i | ϑ i h i 1 ( τ i ) ϑ i ( γ , a ) ( τ i ) | ( γ , a ) τ i i = 1 n h i ( i δ 0 ) 1 ϖ i δ 0 i | ϑ i h i 1 ( τ i ) ϑ i ( γ , a ) ( τ i ) | ν i ( γ , a ) τ i 1 ν i .
Using the inequality for the means [26]
i = 1 n λ i 1 ϖ i 1 i = 1 n 1 ϖ i 1 i = 1 n 1 ϖ i i = 1 n λ i ϖ i , λ i > 0 ( i = 1 , , n ) ,
we have
i = 1 n | ϑ i h i ( i ) | i = 1 n ( i δ 0 ) ϖ i i = 1 n 1 ϖ i n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n h i δ 0 i | ϑ i h i 1 ( τ i ) ϑ i ( γ , a ) ( τ i ) | ν i ( γ , a ) τ i 1 ν i .
Using the integration of (20) on i from δ 0 to ι i ( i = 1 , , n ) , employing the inequality of Hölder’s yields
δ 0 ι 1 δ 0 ι 2 δ 0 ι n i = 1 n | ϑ i h i ( i ) | i = 1 n ( i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) n ( γ , a ) n 1 ( γ , a ) 1 n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n h i δ 0 ι i δ 0 i | ϑ i h i 1 ( τ i ) ϑ i ( γ , a ) ( τ i ) | ν i ( γ , a ) τ i 1 ν i K i = 1 n δ 0 ι i δ 0 i | ϑ i h i 1 ( τ i ) ϑ i ( γ , a ) ( τ i ) | ν i ( γ , a ) τ i ( γ , a ) i 1 ν i = K i = 1 n δ 0 ι i ( ι i i ) | ϑ i h i 1 ( i ) ϑ i ( γ , a ) ( i ) | ν i ( γ , a ) i 1 ν i .
By exploiting the fact that ι i ρ ( ι i ) , we find that
δ 0 ι 1 δ 0 ι 2 δ 0 ι n i = 1 n | ϑ i h i ( i ) | i = 1 n ( i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) n ( γ , a ) n 1 ( γ , a ) 1 K i = 1 n δ 0 ι i ( ρ ( ι i ) ρ ( i ) ) | ϑ i h i 1 ( i ) ϑ i ( γ , a ) ( i ) | ν i ( γ , a ) i 1 ν i .
This concludes the evidence. □
Remark 1.
In Theorem 5, taking T = Z , γ = 1 , h i = 1 , we obtain the results thanks to the authors of ([2], Theorem 1.1).
Remark 2.
In Theorem 5, taking T = R , γ = 1 , we obtain the results thanks to the authors of ([2], Theorem 1.3).
Corollary 1.
In Theorem 5, taking n = 2 , and h 1 = h 2 = 1 , if ν 1 , ν 2 > 1 are such that 1 ν 1 + 1 ν 2 1 and 0 < λ = 2 1 ν 1 1 ν 2 = 1 ϖ 1 + 1 ϖ 2 1 , inequality (17) reduces to
δ 0 ι 1 δ 0 ι 2 | ϑ 1 ( 1 ) | | ϑ 2 ( 2 ) | ϖ 2 ( 1 δ 0 ) + ϖ 1 ( 2 δ 0 ) λ ( γ , a ) 2 ( γ , a ) 1 1 ( λ ϖ 1 ϖ 2 ) λ ( ι 1 δ 0 ) 1 ϖ 1 ( ι 2 δ 0 ) 1 ϖ 2 × δ 0 ι 1 ( ρ ( ι 1 ) ρ ( 1 ) ) | ϑ 1 ( γ , a ) ( 1 ) | ν 1 ( γ , a ) 1 1 ν 1 δ 0 ι 2 ( ρ ( ι 2 ) ρ ( 2 ) ) | ϑ 2 ( γ , a ) ( 2 ) | ν 2 ( γ , a ) 2 1 ν 2 .
Remark 3.
In a special case, taking T = R , γ = 1 , in (22), we have that
0 ι 1 0 ι 2 | ϑ 1 ( 1 ) | | ϑ 2 ( 2 ) | ϖ 2 1 + ϖ 1 2 λ d 2 d 1 1 ( λ ϖ 1 ϖ 2 ) λ ( ι 1 ) 1 ϖ 1 ( ι 2 ) 1 ϖ 2 × 0 ι 1 ( ι 1 1 ) | ϑ 1 ( 1 ) | ν 1 d 1 1 ν 1 0 ι 2 ( ι 2 2 ) | ϑ 2 ( 2 ) | ν 2 d 2 1 ν 2 ,
which is an interesting variation of the inequality (2).
Remark 4.
In a special case, taking T = Z , γ = 1 , in (22), we have that
1 = 1 m 1 2 = 1 m 2 | a 1 ( 1 ) | | a 2 ( 2 ) | ϖ 2 1 + ϖ 1 2 λ 1 ( λ ϖ 1 ϖ 2 ) λ ( m 1 ) 1 ϖ 1 ( m 2 ) 1 ϖ 2 × 1 = 1 m 1 ( m 1 1 + 1 ) | ( γ , a ) a 1 ( 1 ) | ν 1 1 ν 1 2 = 1 m 2 ( m 2 2 + 1 ) | ( γ , a ) a 2 ( 2 ) | ν 2 1 ν 2 ,
which is an interesting variation of the inequality (1).
Corollary 2.
In Corollary 1, if λ = 1 , then 1 ν 1 + 1 ν 2 = 1 ϖ 1 + 1 ϖ 2 = 1 and we take ν 1 = ϖ 2 , ν 2 = ϖ 1 . In this case, inequality (22) reduces to
δ 0 ι 1 δ 0 ι 2 | ϑ 1 ( 1 ) | | ϑ 2 ( 2 ) | ϖ 2 ( 1 δ 0 ) + ϖ 1 ( 2 δ 0 ) ( γ , a ) 2 ( γ , a ) 1 1 ν 1 ϖ 1 ( ι 1 δ 0 ) ν 1 1 ν 1 ( ι 2 δ 0 ) ϖ 1 1 ϖ 1 × δ 0 ι 1 ( ρ ( ι 1 ) ρ ( 1 ) ) | ϑ 1 ( γ , a ) ( 1 ) | ν 1 ( γ , a ) 1 1 ν 1 δ 0 ι 2 ( ρ ( ι 2 ) ρ ( 2 ) ) | ϑ 2 ( γ , a ) ( 2 ) | ϖ 1 ( γ , a ) 2 1 ϖ 1 .
Remark 5.
In Corollary 2, if T = R , γ = 1 , we obtain an equivalent formulation of the inequality that Pachpatte presented in ([27], Theorem 2).
Remark 6.
In Corollary 2, if T = Z , γ = 1 , we obtain an equivalent formulation of the inequality that Pachpatte presented in ([27], Theorem 1).
Theorem 6.
Let T be a time scale with δ 0 , ι i , ς i , i , δ i T , ( i = 1 , , n ) . Let h i 1 , ν i , ϖ i > 1 be constants and 1 ν i + 1 ϖ i = 1 . Let the ( γ , a ) -differentiable fun. ϑ i ( i , δ i ) be decreasing funs. on [ δ 0 , ι i ) T × [ δ 0 , ς i ) T and ϑ i ( δ 0 , δ i ) = ϑ i ( i , δ 0 ) = 0 , for ( i = 1 , , n ) . Partial derivatives of ϑ i are indicated by ϑ i 1 ( γ , a ) , ϑ i 2 ( γ , a ) , ϑ i 12 ( γ , a ) = ϑ i 21 ( γ , a ) . Let
ϑ i h i ( i , δ i ) 1 ( γ , a ) 2 ( γ , a ) h i ϑ i h i 1 ( i , δ i ) . ϑ i 1 ( γ , a ) ( i , δ i ) 2 ( γ , a ) = ϑ i 12 ( γ , a ) ( i , δ i ) .
Then,
δ 0 ι 1 δ 0 ς 1 δ 0 ι n δ 0 ς n i = 1 n | ϑ i h i ( i , δ i ) | i = 1 n ( i δ 0 ) ( δ i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) δ n ( γ , a ) n ( γ , a ) δ 1 ( γ , a ) 1 C i = 1 n δ 0 ι i δ 0 ς i ( ρ ( ι i ) ρ ( i ) ) ( ρ ( ς i ) ρ ( δ i ) ) | ϑ i 12 ( γ , a ) ( i , δ i ) | ν i ( γ , a ) δ i ( γ , a ) i 1 ν i ,
where
C = C ( ι 1 ς 1 , , ι n ς n ) = n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n ( ι i δ 0 ) ( ς i δ 0 ) 1 ϖ i .
Proof. 
We can write
ϑ i h i ( i , δ i ) = ϑ i h i ( i , δ i ) ϑ i h i ( δ 0 , δ i ) ϑ i h i ( i , δ 0 ) + ϑ i h i ( δ 0 , δ 0 ) = δ 0 i ϑ i h i ( ξ i , δ i ) 1 ( γ , a ) 1 ( γ , a ) ξ i δ 0 i ϑ i h i ( ξ i , δ 0 ) 1 ( γ , a ) ( γ , a ) ξ i = δ 0 i ϑ i h i ( ξ i , δ i ) 1 ( γ , a ) ϑ i h i ( ξ i , δ 0 ) 1 ( γ , a ) ( γ , a ) ξ i δ 0 i δ 0 δ i h i ϑ i h i 1 ( ξ i , η i ) . ϑ i 1 ( γ , a ) ( ξ i , η i ) 2 ( γ , a ) ( γ , a ) η i ( γ , a ) ξ i = δ 0 i δ 0 δ i ϑ i 12 ( γ , a ) ( ξ i , η i ) ( γ , a ) η i ( γ , a ) ξ i .
By (27) applying (16) and (28), we obtain
i = 1 n | ϑ i h i ( i , δ i ) | i = 1 n δ 0 i δ 0 δ i | ϑ i 12 ( γ , a ) ( ξ i , η i ) | 1 ( γ , a ) η i 2 ( γ , a ) ξ i i = 1 n ( i δ 0 ) ( δ i δ 0 ) 1 ϖ i δ 0 i δ 0 δ i | ϑ i 12 ( γ , a ) ( ξ i , η i ) | ν i ( γ , a ) η i ( γ , a ) ξ i 1 ν i .
Using inequality (19), we find that
i = 1 n | ϑ i h i ( i , δ i ) | i = 1 n ( i δ 0 ) ( δ i δ 0 ) ϖ i i = 1 n 1 ϖ i n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n δ 0 i δ 0 δ i | ϑ i 12 ( γ , a ) ( ξ i , η i ) | ν i ( γ , a ) η i ( γ , a ) ξ i 1 ν i .
Integrating (29) with i and δ i , and applying (16) and Fubini’s theorem, yields
δ 0 ι 1 δ 0 ς 1 δ 0 ι n δ 0 ς n i = 1 n | ϑ i h i ( i , δ i ) | i = 1 n ( i δ 0 ) ( δ i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) δ n ( γ , a ) n ( γ , a ) δ 1 ( γ , a ) 1 n i = 1 n 1 ν i i = 1 n 1 ν i n × i = 1 n δ 0 ι i δ 0 ς i δ 0 i δ 0 δ i | ϑ i 12 ( γ , a ) ( ξ i , η i ) | ν i ( γ , a ) η i ( γ , a ) ξ i 1 ν i ( γ , a ) δ i ( γ , a ) i n i = 1 n 1 ν i i = 1 n 1 ν i n × i = 1 n ( ι i δ 0 ) ( ς i δ 0 ) 1 ϖ i δ 0 ι i δ 0 ς i δ 0 i δ 0 δ i | ϑ i 12 ( γ , a ) ( ξ i , η i ) | ν i ( γ , a ) η i ( γ , a ) ξ i ( γ , a ) δ i ( γ , a ) i 1 ν i = C i = 1 n δ 0 ι i δ 0 ς i ( ι i i ) ( ς i δ i ) | ϑ i 12 ( γ , a ) ( i , δ i ) | ν i ( γ , a ) δ i ( γ , a ) i 1 ν i .
By exploiting the fact that ι i ρ ( ι i ) , we obtain
δ 0 ι 1 δ 0 ς 1 δ 0 ι n δ 0 ς n i = 1 n | ϑ i h i ( i , δ i ) | i = 1 n ( i δ 0 ) ( δ i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) δ n ( γ , a ) n ( γ , a ) δ 1 ( γ , a ) 1 C i = 1 n δ 0 ι i δ 0 ς i ( ρ ( ι i ) ρ ( i ) ) ( ρ ( ς i ) ρ ( δ i ) ) | ϑ i 12 ( γ , a ) ( i , δ i ) | ν i ( γ , a ) δ i ( γ , a ) i 1 ν i .
This concludes the evidence. □
Remark 7.
In Theorem 6, if we take T = Z , γ = 1 , h i = 1 , we obtain the results thanks to the authors of ([2], Theorem 1.2).
Remark 8.
In Theorem 6, supposing that T = R , γ = 1 , we obtain the results thanks to the authors of ([2], Theorem 1.4).
Corollary 3.
Taking n = 2 and h 1 = h 2 = 1 in Theorem 6, we have
ϑ 1 12 ( γ , a ) ( 1 , δ 1 ) = ϑ 2 ( γ , a ) 1 ( γ , a ) ( 1 , δ 1 ) , ϑ 2 12 ( γ , a ) ( 1 , δ 1 ) = ϑ 2 ( γ , a ) 1 ( γ , a ) ( 2 , δ 2 ) .
Moreover, if ν 1 , ν 2 > 1 satisfy 1 ν 1 + 1 ν 2 1 and 0 < λ = 2 1 ν 1 1 ν 2 = 1 ϖ 1 + 1 ϖ 2 1 , inequality (26) reduces to
δ 0 ι 1 δ 0 ς 1 δ 0 ι 2 δ 0 ς 2 | ϑ 1 ( 1 , δ 1 ) | | ϑ 2 ( 2 , δ 2 ) | ν 1 ( 1 δ 0 ) ( δ 1 δ 0 ) + ϖ 1 ( 2 δ 0 ) ( δ 2 δ 0 ) λ ( γ , a ) 2 ( γ , a ) δ 2 ( γ , a ) 1 ( γ , a ) δ 1 1 λ ϖ 1 ϖ 2 λ ( ι 1 δ 0 ) ( ς 1 δ 0 ) 1 ϖ 1 ( ι 2 δ 0 ) ( ς 2 δ 0 ) ϖ 1 1 ϖ 1 × δ 0 ι 1 δ 0 ς 1 ( ρ ( ι 1 ) ρ ( 1 ) ) ( ρ ( ς 1 ) ρ ( δ 1 ) ) | ϑ 2 ( γ , a ) 1 ( γ , a ) ( 1 , δ 1 ) | ν 1 ( γ , a ) 1 ( γ , a ) δ 1 1 ν 1 δ 0 ι 2 δ 0 ς 2 ( ρ ( ι 2 ) δ 0 ) ( ρ ( ς 2 ) δ 0 ) | ϑ 2 ( γ , a ) 1 ( γ , a ) ( 2 , δ 2 ) | ν 2 ( γ , a ) 2 ( γ , a ) δ 2 1 ν 2 .
Remark 9.
In a unique scenario, if we take T = R in Corollary 3, the inequality (31) reduces to
0 ι 1 0 ς 1 0 ι 2 0 ς 2 | ϑ 1 ( 1 , δ 1 ) | | ϑ 2 ( 2 , δ 2 ) | ν 1 1 δ 1 + ϖ 1 2 δ 2 λ d 2 d δ 2 d 1 d δ 1 1 λ ϖ 1 ϖ 2 λ ι 1 ς 1 1 ϖ 1 ι 2 ς 2 ϖ 1 1 ϖ 1 × 0 ι 1 0 ς 1 ( ι 1 1 ) ( ς 1 δ 1 ) | D 1 D 2 ϑ 1 ( 1 , δ 1 ) | ν 1 d 1 d δ 1 1 ν 1 × 0 ι 2 0 ς 2 ( ι 2 2 ) ( ς 2 δ 2 ) | D 1 D 2 ϑ 2 ( 2 , δ 2 ) | ν 2 d 2 d δ 2 1 ν 2 ,
Remark 10.
In a unique scenario, if we take T = Z in Corollary 3, the inequality (31) reduces to
1 = 1 m 1 δ 1 = 1 n 1 2 = 1 m 2 δ 2 = 1 n 2 | a 1 ( 1 , δ 1 ) | | a 2 ( 2 , δ 2 ) | ν 1 1 δ 1 + ϖ 1 2 δ 2 λ 1 λ ϖ 1 ϖ 2 λ m 1 n 1 1 ϖ 1 m 2 n 2 ϖ 1 1 ϖ 1 × 1 = 1 m 1 δ 1 = 1 n 1 ( n 1 δ 1 ) ( m 1 1 ) | 1 ( γ , a ) 2 ( γ , a ) a 1 ( 1 , δ 1 ) | ν 1 1 ν 1 × 2 = 1 m 2 δ 2 = 1 n 2 ( n 2 δ 2 ) ( m 2 2 ) ) | 1 ( γ , a ) 2 ( γ , a ) a 2 ( 2 , δ 2 ) | ν 2 1 ν 2 ,
Corollary 4.
In Corollary 3, if λ = 1 , then 1 ν 1 + 1 ν 2 = 1 ϖ 1 + 1 ϖ 2 = 1 , and we take ν 1 = ϖ 2 , ν 2 = ϖ 1 . In this case, the inequality (31) reduces to
δ 0 ι 1 δ 0 ς 1 δ 0 ι 2 δ 0 ς 2 | ϑ 1 ( 1 , δ 1 ) | | ϑ 2 ( 2 , δ 2 ) | ν 1 ( 1 δ 0 ) ( δ 1 δ 0 ) + ϖ 1 ( 2 δ 0 ) ( δ 2 δ 0 ) ( γ , a ) 2 ( γ , a ) δ 2 ( γ , a ) 1 ( γ , a ) δ 1 1 ν 1 ϖ 1 ( ι 1 δ 0 ) ( ς 1 δ 0 ) ν 1 1 ν 1 ( ι 2 δ 0 ) ( ς 2 δ 0 ) ϖ 1 1 ϖ 1 × δ 0 ι 1 δ 0 ς 1 ( ρ ( ι 1 ) ρ ( 1 ) ) ( ρ ( ς 1 ) ρ ( δ 1 ) ) | ϑ 2 ( γ , a ) 1 ( γ , a ) ( 1 , δ 1 ) | ν 1 ( γ , a ) 1 ( γ , a ) δ 1 1 ν 1 δ 0 ι 2 δ 0 ς 2 ( ρ ( ι 2 ) δ 0 ) ( ρ ( ς 2 ) δ 0 ) | ϑ 2 ( γ , a ) 1 ( γ , a ) ( 2 , δ 2 ) | ν 2 ( γ , a ) 2 ( γ , a ) δ 2 1 ν 2 .
Remark 11.
In Corollary 4, if T = R , γ = 1 , we obtain an equivalent formulation of the inequality that Pachpatte presented in ([27], Theorem 4).
Remark 12.
In Corollary 4, if T = Z , γ = 1 , we obtain an equivalent formulation of the inequality that Pachpatte presented in ([27], Theorem 3).
Theorem 7.
Let T be a time scale with δ 0 , ι i j , τ i j , δ i j T , ( i , j = 1 , , n ) . Let ν i , ϖ i > 1 , be constants and 1 ν i + 1 ϖ i = 1 . Let ϑ i ( τ 1 i , , τ n i ) be real-valued nth ( γ , a ) -differentiable functions also defined on [ δ 0 , ι 1 i ) T × × [ δ 0 , ι n i ) T , where δ 0 ι j i δ j i , δ j i ( 0 , ) and i , j = 1 , , n . Suppose
ϑ i ( ι 1 i , , ι n i ) = δ 0 ι 1 i δ 0 ι n i n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) ( γ , a ) τ n i ( γ , a ) τ 1 i ,
then
δ 0 δ 11 δ 0 δ n 1 δ 0 δ 12 δ 0 δ n 2 δ 0 δ 1 n δ 0 δ n n i = 1 n δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i 1 ν i i = 1 n ( ι 1 i δ 0 ) ( ι n i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) ι 11 ( γ , a ) ι n 1 ( γ , a ) ι 12 ( γ , a ) ι n 2 ( γ , a ) ι 1 n ( γ , a ) ι n n N i = 1 n δ 0 δ 1 i δ 0 δ n i j = 1 n ( ρ ( δ j i ) ι j i ) | n ( γ , a ) ι 1 i ( γ , a ) ι n i ϑ i ( ι 1 i , , ι n i ) | ν i ( γ , a ) ι 1 i ( γ , a ) ι n i 1 ν i ,
where
N = N ( δ 1 i , , δ n i ) n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n ( δ 1 i δ 0 ) ( δ n i δ 0 ) 1 ϖ i .
Proof. 
From the hypothesis of Theorem 7, we have
| ϑ i ( ι 1 i , , ι n i ) | δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ( γ , a ) τ n i ( γ , a ) τ 1 i .
On the other hand, by using (19) and Hölder’s dynamic inequality, we obtain
i = 1 n | ϑ i ( ι 1 i , , ι n i ) | i = 1 n δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ( γ , a ) τ n i ( γ , a ) τ 1 i i = 1 n ( ι 1 i δ 0 ) ( ι n i δ 0 ) 1 ϖ i × δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i , , ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i 1 ν i i = 1 n ( ι 1 i δ 0 ) ( ι n i δ 0 ) ϖ i i = 1 n 1 ϖ i n i = 1 n 1 ν i n i = 1 n 1 ν i × i = 1 n δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i 1 ν i .
Divide (37) by i = 1 n ( ι 1 i δ 0 ) ( ι n i δ 0 ) ϖ i i = 1 n 1 ϖ i , and then integrate it over ι j i from δ 0 to δ j i ( i , j = 1 , , n ) , respectively; using the dynamic Hölder inequality and using the information ρ ( n ) n , we obtain
δ 0 δ 11 δ 0 δ n 1 δ 0 δ 12 δ 0 δ n 2 δ 0 δ 1 n δ 0 δ n n i = 1 n δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i 1 ν i i = 1 n ( ι 1 i δ 0 ) ( ι n i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) ι 11 ( γ , a ) ι n 1 ( γ , a ) ι 12 ( γ , a ) ι n 2 ( γ , a ) ι 1 n ( γ , a ) ι n n n i = 1 n 1 ν i i = 1 n 1 ν i n × i = 1 n δ 0 δ 1 i δ 0 δ n i δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i , , ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i 1 ν i ( γ , a ) ι n i ( γ , a ) ι 1 i n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n ( δ 1 i δ 0 ) ( δ n i δ 0 ) 1 ϖ i δ 0 δ 1 i δ 0 δ n i δ 0 ι 1 i δ 0 ι n i | n ( γ , a ) τ 1 i ( γ , a ) τ n i ϑ i ( τ 1 i , , τ n i ) | ν i ( γ , a ) τ n i ( γ , a ) τ 1 i ( γ , a ) ι n i ( γ , a ) ι 1 i 1 ν i = N i = 1 n δ 0 δ 1 i δ 0 δ n i j = 1 n ( δ j i ι j i ) | n ( γ , a ) ι 1 i ( γ , a ) ι n i ϑ i ( ι 1 i , , ι n i ) | ν i ( γ , a ) ι n i ( γ , a ) ι 1 i 1 ν i N i = 1 n δ 0 δ 1 i δ 0 δ n i j = 1 n ( ρ ( δ j i ) ι j i ) | n ( γ , a ) ι 1 i ( γ , a ) ι n i ϑ i ( ι 1 i , , ι n i ) | ν i ( γ , a ) ι n i ( γ , a ) ι 1 i 1 ν i .
This concludes the evidence. □
Remark 13.
In Theorem 7, supposing Z = T , a n d w i t h   γ = 1 , we obtain ([3], Theorem 2.1).
Remark 14.
In Theorem 7, supposing R = T , a n d w i t h   γ = 1 , we obtain ([3], Theorem 2.2).
Corollary 5.
Let ϑ i ( ι 1 i , , ι n i ) change to ϑ i ( i ) in Theorem 7 and in view of ϑ i ( δ 0 ) = 0 , ( i = 1 , , n ) , and then
δ 0 ι 1 δ 0 ι 2 δ 0 ι n i = 1 n | ϑ i ( i ) | i = 1 n ( i δ 0 ) ϖ i i = 1 n 1 ϖ i ( γ , a ) n ( γ , a ) n 1 ( γ , a ) 1 R i = 1 n δ 0 ι i ( ρ ( ι i ) ρ ( i ) ) | ϑ i ( γ , a ) ( i ) | ν i ( γ , a ) τ i ( γ , a ) i 1 ν i ,
where
R = n i = 1 n 1 ν i i = 1 n 1 ν i n i = 1 n ( ι i δ 0 ) 1 ϖ i .
Remark 15.
Taking n = 2 , in Corollary 5, if ν 1 , ν 2 > 1 are such that 1 ν 1 + 1 ν 2 1 and 0 < λ = 2 1 ν 1 1 ν 2 = 1 ϖ 1 + 1 ϖ 2 1 , inequality (38) reduces to inequality (22).

3. Conclusions

In this work, we used Holder’s inequality to prove a number of Hilbert’s inequalities on the time scale. Some integer and discrete inequalities were obtained as special cases of the results. This work builds on the multiple inequalities reported by Pachpatte in 1998 and 2000 and by Handley et al. and by Zhao et al. in 2012. Moreover, as a future work, we intend to extend these inequalities by 123 using a-conformable calculus and also by employing alpha-conformable calculus on time scales. Moreover, we will try to obtain the diamond alpha version for these results.

Author Contributions

Resources, methodology and investigations, A.A.E.-D. and B.A.; writing—original draft preparation, A.A.E.-D. and B.A.; conceptualization, writing—review and editing, A.A.E.-D. and B.A. All authors have read and approved the final manuscript.

Funding

Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2023R216), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

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Almarri, B.; El-Deeb, A.A. Gamma-Nabla Hardy–Hilbert-Type Inequalities on Time Scales. Axioms 2023, 12, 449. https://doi.org/10.3390/axioms12050449

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Almarri B, El-Deeb AA. Gamma-Nabla Hardy–Hilbert-Type Inequalities on Time Scales. Axioms. 2023; 12(5):449. https://doi.org/10.3390/axioms12050449

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Almarri, Barakah, and Ahmed A. El-Deeb. 2023. "Gamma-Nabla Hardy–Hilbert-Type Inequalities on Time Scales" Axioms 12, no. 5: 449. https://doi.org/10.3390/axioms12050449

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