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Article

Theoretical Results on the pth Moment of ϕ-Hilfer Stochastic Fractional Differential Equations with a Pantograph Term

by
Abdelhamid Mohammed Djaouti
1,*,† and
Muhammad Imran Liaqat
2,†
1
Department of Mathematics and Statistics, Faculty of Sciences, King Faisal University, Hofuf 31982, Saudi Arabia
2
Abdus Salam School of Mathematical Sciences, Government College University, 68-B, New Muslim Town, Lahore 54600, Pakistan
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Fractal Fract. 2025, 9(3), 134; https://doi.org/10.3390/fractalfract9030134
Submission received: 24 January 2025 / Revised: 15 February 2025 / Accepted: 18 February 2025 / Published: 20 February 2025

Abstract

Here, we establish significant results on the well-posedness of solutions to stochastic pantograph fractional differential equations (SPFrDEs) with the ϕ -Hilfer fractional derivative. Additionally, we prove the smoothness theorem for the solution and present the averaging principle result. Firstly, the contraction mapping principle is applied to determine the existence and uniqueness of the solution. Secondly, continuous dependence findings are presented under the condition that the coefficients satisfy the global Lipschitz criteria, along with regularity results. Thirdly, we establish results for the averaging principle by applying inequalities and interval translation techniques. Finally, we provide numerical examples and graphical results to support our findings. We make two generalizations of these findings. First, in terms of the fractional derivative, our established theorems and lemmas are consistent with the Caputo operator for ϕ ( t ) = t , a = 1 . Our findings match the Riemann–Liouville fractional operator for ϕ ( t ) = t , a = 0 . They agree with the Hadamard and Caputo–Hadamard fractional operators when ϕ ( t ) = ln ( t ) , a = 0 and ϕ ( t ) = ln ( t ) , a = 1 , respectively. Second, regarding the space, we are make generalizations for the case p = 2 .

1. Introduction

The literature contains various types of fractional operators; the most important and commonly used are the Caputo and Riemann–Liouville derivatives. In 2000, Hilfer generalized the Riemann–Liouville derivative, which is known as the Hilfer fractional derivative (HFrD). In 2018, Sousa and Oliveira further generalized HFrD, defining it with respect to an increasing function ϕ ( t ) to enhance the precision of objective modeling.
Various authors have utilized the ϕ -HFrD with fractional differential equations (FDEs) and fractional stochastic differential equations (FSDEs) to analyze multiple concepts. For example, Raheem et al. [1] presented controllability results for FSDEs and discussed the existence of a solution. Lavanya et al. [2] also explored controllability for FSDEs with the Rosenblatt process. Gokul and Udhayakumar [3] examined approximate controllability through sectorial operators. The authors [4] have presented stability results for FDEs with ϕ -HFrD and established various concepts related to the solutions of fractional integro-differential equations. Kucche and Mali [5] proved the existence of solutions for FDEs with ϕ -HFrD, while Bonilla et al. [6] investigated the solvability of such equations. Additionally, Lima et al. [7] provided results on Ulam–Hyers stability for FDEs with delay in the context of ϕ -HFrD. Abdo et al. [8] studied a fractional system in the sense of ϕ -HFrD and explored various concepts. Finally, the authors [9] established the approximate controllability of FDEs with ϕ -HFrD.
The Riemann–Liouville fractional integral of order q with respect to an increasing, non-vanishing, and monotonic function ϕ ( t ) for a continuous function f : [ u , g ] R , as given below [10]:
I u q , ϕ f ( t ) = 1 Γ ( q ) u t ϕ ( ϖ ) ϕ ( t ) ϕ ( ϖ ) q 1 f ( ϖ ) d ϖ .
The Riemann–Liouville fractional operator of order q for ϕ ( t ) is given as follows [10]:
T u + q , ϕ f ( t ) = 1 ϕ ( t ) d d t δ I a δ q , ϕ f ( t ) = 1 Γ ( δ q ) 1 ϕ ( t ) d d t δ u t ϕ ( ϖ ) ϕ ( t ) ϕ ( ϖ ) δ q 1 f ( ϖ ) d ϖ .
where q ( δ 1 , δ ) .
The ϕ -HFrD of order q and type a for the function f ( t ) is defined as [11]:
T u + q , a , ϕ H f ( t ) = I u + a ( δ q ) , ϕ 1 ϕ ( t ) d d t δ I u + ( 1 a ) ( δ q ) , ϕ f ( t ) ,
where δ = [ q ] + 1 , δ N , and ϕ is an increasing function.
Stochastic differential equations with fractional calculus have drawn a lot of interest and have been used in a number of study fields, such as quantitative finance, option pricing, and disease transmission. Numerous scholars have investigated various important results related to FSDEs, such as the existence and uniqueness (EU) of the solution, stability, regularity, controllability, and averaging principle (AP). Some important works include the use of the Picard approach by the authors in [12] to examine the stability and EU of solutions for FSDEs. Their results were developed in the L 2 space, and they established the results with the Caputo fractional derivative (CFD). The Hadamard operator was used in [13] to establish results on a number of different features, including stability and EU, with findings expressed in the L 2 space. The EU of FSDEs containing fractional derivatives of a variable order was the main emphasis of Moualkia and Xu [14]. Babaei et al. [15] used the collocation approach with CFD to find solutions for FSDEs. FSDEs were solved using the Taylor series method by Asai and Kloeden [16]. The Picard approach with CFD was used by the authors in [17] to establish the EU results. In their study, Zhang et al. [18] investigated EU for FSDEs with delay while taking the CFD into account. Using the Hadamard operator, Lavanya and Vadivoo [19] examined the controllability of FSDEs with fractional Brownian motion. The Euler–Maruyama method was used to develop solutions for FSDEs in [20], along with stability and EU results. The Euler–Maruyama method’s strong convergence was examined by Yang et al. [21]. In [22], the authors looked at EU and controllability for FSDEs with CFD. A large portion of the literature has been developed inside the framework of L 2 space. The authors of [23] presented some important results for the stochastic Burgers system.
The concept of the AP was introduced by Khasminskii [24], who demonstrated that the average and original solutions of a system coincided under suitable restrictions. Using the AP tool, complex systems can be studied by approximating an average system, making it easier to analyze systems that are otherwise difficult to study directly. In the literature, AP results have been proven for various types of systems under appropriate conditions, with some of the most significant being: Mao et al. [25] proved a result for the AP using jumps for delay stochastic systems. Xu et al. [26] discussed AP for FSDEs with the Caputo operator with a mean square. Guo et al. [27] established a theorem for AP under weak conditions. Liu and Xu [28] studied AP for impulsive FSDEs with the Caputo operator. Liu et al. [29] presented a result on AP for partial FSDEs with the Caputo operator with a mean square. Ahmed and Zhu [30] also proved a theorem for FSDEs with Poisson jumps under the Hilfer operator. Xu et al. [31] further explored AP for FSDEs with a mean square. Additionally, the authors investigated AP for backward stochastic system in L 2 space. Jing and Li [32] discussed the AP for the stochastic model in the mean square sense. Guo et al. [33] also presented a result for the AP in the mean square sense. In the sense of the Caputo fractional operator, Mouy et al. [34] also worked on AP with the Caputo–Hadamard fractional operator in the mean square sense. In [35], Shen et al. discussed the AP for the fractional heat system. The authors [36,37] also established results regarding AP in the L 2 space. For further results on AP regarding fractional operators and space, see [38,39,40].
In this research, we present significant results concerning the EU, continuous dependence, regularity, and AP for SPFrDEs with ϕ -HFrD in the p th moment. Using the contraction mapping principle, we establish the EU result for the solutions of SPFrDEs, then prove the results for continuous dependence under the condition that the coefficients satisfy the global Lipschitz criteria. Additionally, we prove regularity results and, by applying various inequalities and the interval translation approach, derive results for the AP. Finally, we provide numerical examples and graphical representations to support our findings.
This study makes notable contributions in the following ways:
  • To the best of our knowledge, this is the first research work to establish results regarding well-posedness, regularity, and AP for SPFrDEs concerning ϕ -HFrD.
  • The majority of results in the literature concerning the EU and AP for FSDEs were developed in the mean square sense; however, we derived these results using the p th moment. Consequently, our research expanded the findings about regularity, well-posedness, and the AP for SPFrDEs to p = 2 .
  • For ϕ ( t ) = t , a = 1 our established results align with the FSDEs of CFD. For ϕ ( t ) = t , a = 0 our results correspond to the FSDEs of the Riemann–Liouville fractional operator. When ϕ ( t ) = ln ( t ) a = 0 , and ϕ ( t ) = ln ( t ) a = 1 , they align with the Hadamard and Caputo–Hadamard, respectively.
  • We present some numerical problems and their graphical results to prove the validity of our established theoretical results.
We examine the following SPFrDEs:
{ T t q , a , ϕ H f ( t ) = D ( t , f ( t ) , f ( s t ) ) + Ξ ( t , f ( t ) , f ( s t ) ) d W ( t ) d t , I 0 + ( 1 q ) ( 1 a ) , ϕ f ( 0 ) = c .
where s ( 0 , 1 ) , ϕ is an increasing function, and T t q , a , ϕ H represents the ϕ -HFrD with q ( 1 2 , 1 ) and 0 a 1 , the functions D : [ 0 , g ] × R ϰ × R ϰ R ϰ and Ξ : [ 0 , g ] × R ϰ × R ϰ R ϰ × b are measurable continuous mappings.
This research includes several essential components: In the following section, we outline the fundamental concepts and assumptions. Subsequently, we discuss the well-posedness and regularity of solutions and the AP results for SPFrDEs concerning ϕ -HFrD in Section 3 and Section 4, respectively. The next four examples, along with the graphical results, are presented. Finally, our conclusions are summarized in Section 6.

2. Preliminaries

We now outline the definitions and assumptions that underpin the findings of this research study.
Lemma 1 
([41]). Let f 1 ( t ) L p and f 2 ( t ) L q . Then, Hölder’s inequality is defined as follows:
f 1 f 2 1 f 1 p f 2 q ,
where 1 p + 1 q = 1 .
Lemma 2 
([42]). Assume that there are real numbers β 1 , β 2 , β 3 , , β n ( n N ) with β ι 0 , ( ι = 1 , 2 , 3 , n ) . Then, Jensen’s inequality is as follows:
ι = 1 n β ι p n p 1 ι = 1 n β ι p , p > 1 .
where 1 p + 1 q = 1 .
Definition 1 
([43]). Let G : X R be a measurable function on a measure space ( X , Σ , U ) . The essential supremum of G , denoted as is the smallest real number Q , such that G ( τ ) Q almost everywhere, meaning:
U { τ X G ( τ ) > Q } = 0 .
A measurable procedure f ( t ) : [ 0 , g ] L p ( Ω , F , p ) is an F adapted process when f ( t ) Z t p with t 0 . The integral form of (4) is as follows:
f ( t ) = c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ϕ ( ϖ ) D ϖ , f ( ϖ ) , f ( s ϖ ) d ϖ + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ϕ ( ϖ ) Ξ ϖ , f ( ϖ ) , f ( s ϖ ) d W ( ϖ ) .
For M and B , we assume the following Lipschitz conditions, which are a fundamental criterion for proving the EU of solutions to differential equations.
  • ( ξ 1 ) A 1 , A 2 , ν 1 , ν 2 R ϰ there are T 1 > 0 and T 2 > 0 , such as
    D ( t , A 1 , A 2 ) D ( t , ν 1 , ν 2 ) p T 1 A 1 ν 1 p + A 2 ν 2 p .
    Ξ ( t , A 1 , A 2 ) Ξ ( t , ν 1 , ν 2 ) p T 2 A 1 ν 1 p + A 2 ν 2 p .
  • ( ξ 2 ) The D ( t , 0 , 0 ) and Ξ ( t , 0 , 0 ) are essential bounded, so
    e s s s u p t [ 0 , g ] D ( t , 0 , 0 ) p < γ , e s s s u p t [ 0 , g ] Ξ ( t , 0 , 0 ) p < γ .
Now, assume the following:
  • ( ξ 3 ) : A 1 , A 2 , ν 1 , ν 2 R ϰ , t [ 0 , g ] there is a T 3 > 0 , such that:
    D ( t , A 1 , A 2 ) D ( t , ν 1 , ν 2 ) Ξ ( t , A 1 , A 2 ) Ξ ( t , ν 1 , ν 2 ) T 3 A 1 ν 1 + A 2 ν 2 .
  • ( ξ 4 ) : For A , ν R ϰ , t [ 0 , g ] , there is T 4 > 0 , such as satisfy the following:
    D ( t , A , ν ) Ξ ( t , A , ν ) T 4 1 + A + ν .
  • ( ξ 5 ) : For g 1 [ 0 , g ] , t [ 0 , g ] , and p 2 , we have
    1 g 1 0 g 1 D ( t , A , ν ) D ˜ ( t , A , ν ) p d t D 1 ( g 1 ) 1 + A p + ν p ,
    1 g 1 0 g 1 Ξ ( t , A , ν ) Ξ ˜ ( t , A , ν ) p d t D 2 ( g 1 ) 1 + A p + ν p ,
where lim g 1 D 1 ( g 1 ) = 0 , lim g 1 D 2 ( g 1 ) = 0 and D 1 ( g 1 ) , D 2 ( g 1 ) are positively bounded functions.

3. Significant Outcomes

We prove the well-posedness and regularity for the solution of SPFrDEs in this section.

3.1. Well-Posedness

In this sub-section, we prove EU for the solution of SPFrDEs by using the contraction mapping principle, and then we prove that the solution depends continuously on the fractional and initial values. Assume that H p ( 0 , g ) is the space of the F g adapted process, where F g = ( F t ) t [ 0 , g ] , and we have
f H p = e s s s u p t [ 0 , g ] f ( t ) p < .
Clearly, H p ( 0 , g ) , · H p is a Banach space. Let ψ c : H p ( 0 , g ) H p ( 0 , g ) with ψ c ( f ( 0 ) ) = c and
ψ c ( f ( t ) ) = c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ϕ ( ϖ ) D ϖ , f ( ϖ ) , f ( s ϖ ) d ϖ + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ϕ ( ϖ ) Ξ ϖ , f ( ϖ ) , f ( s ϖ ) d W ( ϖ ) .
The following lemma is very important in order to prove various results.
f 1 + f 2 p p 2 p 1 ( f 1 p p + f 2 p p ) , f 1 , f 2 R ϰ .
Lemma 3. 
Let ξ 1 and ξ 2 hold. Then, ψ c is well-defined.
Proof. 
Suppose f ( t ) H p [ 0 , g ] and t [ 0 , g ] . From (7) and (8), we have
ψ c ( f ( t ) ) p p 2 p 1 c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) p p + 2 2 p 2 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d ϖ p p + 2 2 p 2 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p .
By Hölder’s inequality (HI) we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d ϖ p p = ı = 1 m E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 | D ı ϖ , f ( ϖ ) , f ( s ϖ ) | ϕ ( ϖ ) d ϖ p ı = 1 m E ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) p ( p 1 ) ( ϕ ( ϖ ) ) p p 1 d ϖ p 1 0 t | D ı ϖ , f ( ϖ ) , f ( s ϖ ) | p d ϖ ) ı = 1 m E ( sup 0 < ϖ t ϕ ( ϖ ) 1 p 1 p 1 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) p ( p 1 ) ϕ ( ϖ ) d ϖ p 1 0 t | D ı ϖ , f ( ϖ ) , f ( s ϖ ) | p d ϖ ) p 1 ϕ ( ϖ ) ϕ ( 0 ) q p 1 p 1 p 1 p 1 q p 1 p 1 0 t D ϖ , f ( ϖ ) , f ( s ϖ ) p p d ϖ .
where = sup 0 < ϖ t ϕ ( ϖ ) 1 p 1 .
The detailed methodology used to simplify (10) is outlined in Appendix A.1. So, from (10), we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d ϖ p p p 1 ϕ ( ϖ ) ϕ ( 0 ) ( q p 1 ) p 1 p 1 p 1 q p 1 p 1 2 p 1 ( T 1 p g ( f ( ϖ ) H p p + f ( s ϖ ) H p p ) + g γ p ) .
By the Burkholder–Davis–Gundy inequality (BDGI) and HI, we obtain
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p = ı = 1 m E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ı ( ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) | p ı = 1 m C p E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) | 2 ϕ ( ϖ ) 2 d ϖ | p 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) | p ϕ ( ϖ ) 2 d ϖ 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ p 2 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) | p ϕ ( ϖ ) 2 d ϖ sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ p 2 2 G p 2 2 C p ϕ ( t ) ϕ ( 0 ) 2 q 1 2 q 1 p 2 2 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 Ξ ϖ , f ( ϖ , f ( s ϖ ) p p ϕ ( t ) 2 d ϖ ,
where G = sup 0 < ϖ t ϕ ( ϖ ) and C p = p p + 1 2 ( p 1 ) p 1 p 2 .
The detailed methodology used to simplify (12) is outlined in Appendix A.2. Thus, from (12), we obtain
0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) p p ϕ ( ϖ ) 2 d ϖ 2 p 1 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) G ( T 2 p f ( ϖ ) H p p + f ( s ϖ ) H p p + γ p ) .
Using (13) in (12), we obtain
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p G p 2 2 C p ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 2 p 1 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) G ( T 2 p f ( ϖ ) H p p + f ( s ϖ ) H p p + γ p ) .
Hence ψ ( f ( t ) ) H p < . So, ψ c is well-defined. □
The following lemma is important for EU.
Lemma 4. 
Assume q , Υ > 0 , and t [ 0 , g ] , then
I 0 + q , ϕ exp Υ ϕ ( ϖ ) ϕ ( 0 ) exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ q .
Proof. 
From (1), we obtain:
I 0 + q , ϕ exp Υ ϕ ( ϖ ) ϕ ( 0 ) = 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 exp Υ ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ .
By K = ϕ ( t ) ϕ ( ϖ ) ,
I 0 + q , ϕ exp Υ ϕ ( ϖ ) ϕ ( 0 ) = Υ ϕ ( ϖ ) ϕ ( 0 ) Γ ( q ) 0 ϕ ( t ) ϕ ( 0 ) K q 1 exp ( Υ K ) d K .
Apply V = Υ K in (15),
I 0 + q , ϕ exp Υ ϕ ( ϖ ) ϕ ( 0 ) = exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ q Γ ( q ) 0 Υ ( ϕ ( ϖ ) ϕ ( 0 ) ) V q 1 exp ( V ) d V exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ q Γ ( q ) 0 V q 1 exp ( V ) d V = exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ q .
Thus, we have
1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 exp Υ ϕ ( ϖ ) ϕ ( 0 ) d ϖ exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ q .
Now, the EU of solution is demonstrated by proving that the operator ψ c is contractive with respect to an appropriate weighted norm.
Theorem 1. 
Suppose ( ξ 1 ) and ( ξ 2 ) hold; then, system (4) has a unique solution.
Proof. 
Taking Υ as
Υ 2 q 1 > 2 Z Γ ( 2 q 1 ) ,
where
Z = 2 p 1 ( Γ ( q ) ) p ( ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 G + G p 2 2 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 T 2 p C p G ) .
The · Υ is
f ( t ) Υ = e s s s u p t [ 0 , g ] f ( t ) p p exp Υ ϕ ( ϖ ) ϕ ( 0 ) 1 p , f ( t ) H p ( [ 0 , g ] ) .
As the norms · H p and · Υ are equivalent. So, H p ( 0 , g ) , · Υ is also a Banach space.
For f ( t ) and f ˜ ( t ) , we obtain
ψ c ( f ( t ) ) ψ c ( f ˜ ( t ) ) p p 2 p 1 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) D ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d ϖ p p + 2 p 1 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p .
Using the HI and ( ξ 1 ) , we obtain
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) D ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d ϖ p p = ı = 1 m E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ı ϖ , f ( ϖ ) , f ( s ϖ ) D ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d ϖ p ı = 1 m E ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) ( p 2 ) p 1 ϕ ( ϖ ) p 2 p 1 d ϖ p 1 ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | D ı ϖ , f ( ϖ ) , f ( s ϖ ) D ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ) | ϕ ( ϖ ) d ϖ ) ı = 1 m E ( sup 0 < ϖ t ϕ ( ϖ ) 1 1 p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) ( p 2 ) p 1 ϕ ( ϖ ) d ϖ p 1 ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | D ı ϖ , f ( ϖ ) , f ( s ϖ ) D ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ) | ϕ ( ϖ ) 2 d ϖ ) ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 f ( ϖ ) f ˜ ( ϖ ) ) p p + f ( s ϖ ) f ˜ ( s ϖ ) ) p p ϕ ( ϖ ) d ϖ .
where ϝ = sup 0 < ϖ t ϕ ( ϖ ) 1 1 p .
Hence, we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) D ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d ϖ p p G ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 f ( ϖ ) f ˜ ( ϖ ) ) p p + f ( s ϖ ) f ˜ ( s ϖ ) ) p p ϕ ( ϖ ) d ϖ .
Now, using ( ξ 1 ) and the BDGI, we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p = ı = 1 m E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) | p ı = 1 m C p E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) | 2 ϕ ( ϖ ) 2 d ϖ | p 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) | p ϕ ( ϖ ) 2 d ϖ 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ p 2 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ı ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) | p ϕ ( ϖ ) 2 d ϖ sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ p 2 2 G p 2 2 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 T 2 p C p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 f ( ϖ ) f ˜ ( ϖ ) p p + f ( s ϖ ) f ˜ ( s ϖ ) p p ϕ ( ϖ ) 2 d ϖ . G p 2 2 ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 T 2 p C p sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 f ( ϖ ) f ˜ ( ϖ ) p p + f ( s ϖ ) f ˜ ( s ϖ ) p p ϕ ( ϖ ) d ϖ .
From the above, we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) Ξ ϖ , f ˜ ( ϖ ) , f ˜ ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p G p 2 2 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 T 2 p C p G 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 f ( ϖ ) f ˜ ( ϖ ) p p + f ( s ϖ ) f ˜ ( s ϖ ) p p ϕ ( ϖ ) d ϖ .
Thus, t [ 0 , g ] , we have
ψ c f ( t ) ψ c f ˜ ( t ) p p Z 0 t f ( ϖ ) f ˜ ( ϖ ) p p + f ( s ϖ ) f ˜ ( s ϖ ) p p ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ ,
So,
ψ c f ( t ) ψ c f ˜ ( t ) p p exp Υ ϕ ( ϖ ) ϕ ( 0 ) 1 exp Υ ϕ ( ϖ ) ϕ ( 0 ) Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 exp Υ ϕ ( ϖ ) ϕ ( 0 ) ) f ( ϖ ) f ˜ ( ϖ ) p p exp Υ ϕ ( ϖ ) ϕ ( 0 ) + exp Υ s ϕ ( ϖ ) ϕ ( 0 ) f ( s ϖ ) f ˜ ( s ϖ ) p p exp Υ s ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ 1 exp Υ ϕ ( ϖ ) ϕ ( 0 ) Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ( exp Υ ϕ ( ϖ ) ϕ ( 0 ) e s s s u p ϖ [ 0 , g ] f ( ϖ ) f ˜ ( ϖ ) p p exp Υ ϕ ( ϖ ) ϕ ( 0 ) + exp Υ s ϕ ( ϖ ) ϕ ( 0 ) e s s s u p ϖ [ 0 , g ] f ( s ϖ ) f ˜ ( s ϖ ) p p exp Υ s ϕ ( ϖ ) ϕ ( 0 ) ) ϕ ( ϖ ) d ϖ f ( ϖ ) f ˜ ( ϖ ) Υ p exp Υ ϕ ( ϖ ) ϕ ( 0 ) Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 exp Υ ϕ ( ϖ ) ϕ ( 0 ) + exp Υ s ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ 2 f ( ϖ ) f ˜ ( ϖ ) Υ p exp Υ ϕ ( ϖ ) ϕ ( 0 ) Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 exp Υ ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ .
Now, replace q by 2 q 1 in (16).
1 Γ ( 2 q 1 ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 exp Υ ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ 2 q 1 .
From above
0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 exp Υ ϕ ( ϖ ) ϕ ( 0 ) ϕ ( ϖ ) d ϖ Γ ( 2 q 1 ) exp Υ ϕ ( ϖ ) ϕ ( 0 ) Υ 2 q 1 .
So,
ψ c f ( t ) ψ c f ˜ ( t ) Υ 2 Z Γ ( 2 q 1 ) Υ 2 q 1 1 p f ( ϖ ) f ˜ ( ϖ ) Υ .
From (17), we have Z Γ ( 2 q 1 ) Υ 2 q 1 < 1 . □
Theorem 2. 
Suppose ξ 1 and ξ 2 hold, then
lim q q ˜ e s s s u p t [ 0 , g ] B q ( t , c ) B q ˜ ( t , c ) p = 0 ,
where B q ( t , c ) is the solution.
Proof. 
Suppose q , q ˜ ( 1 2 , 1 ) . We obtain the following:
B q ( t , c ) B q ˜ ( c , t ) = 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ( ϖ , B q ( ϖ , c ) ) D ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d ϖ + 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) D ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d ϖ + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ( ϖ , B q ( ϖ , c ) ) Ξ ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) + 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) Ξ ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) .
We extract the subsequent outcome from (28) employing (8).
B q ( t , c ) B q ˜ ( t , c ) p p 2 p 1 Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( t , c ) B q ˜ ( c , t ) p p d ϖ + 2 2 p 2 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) D ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d ϖ p p + 2 2 p 2 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) Ξ ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) p p .
Assume
A ( t , ϖ , q , q ˜ , ϕ ) = | ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) | ϕ ( ϖ ) .
By HI, ( ξ 1 ) , ( ξ 2 ) , and (8), we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) D ( ϖ , B q ˜ ( ϖ , c ) ϕ ( ϖ ) d ϖ p p = ι = 1 m E 0 t A ( t , ϖ , q , q ˜ , ϕ ) | D ı ( ϖ , B q ˜ ( ϖ , c ) ) | d ϖ p ι = 1 m E ( 0 t A ( t , ϖ , q , q ˜ , ϕ ) p p 1 p 1 0 t D ı ( ϖ , B q ˜ ( ϖ , c ) | p d ϖ 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 p 2 0 t 1 d ϖ p 2 2 0 t D ( ϖ , B q ˜ ( ϖ , c ) p p d ϖ 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 p 2 g p 2 2 0 t 2 p 1 T 1 p B q ˜ ( ϖ , c ) p p ) + D ( ϖ , 0 ) p p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 p 2 g p 2 2 p 1 T 1 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p ) + γ p .
Utilizing (30), ( ξ 1 ) , and ( ξ 2 ) in (29).
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Γ ( q ) ( ϕ ( t ) ϕ ( ϖ ) ) q ˜ 1 Γ ( q ˜ ) Ξ ( ϖ , B q ˜ ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) p p = ι = 1 m E | 0 t A ( t , ϖ , q , q ˜ , ϕ ) Ξ ı ( ϖ , B q ˜ ( ϖ , c ) ) d W ( ϖ ) | p ι = 1 m C p E | 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 | Ξ ı ( ϖ , B q ˜ ( ϖ , c ) ) | 2 d W ( ϖ ) | p 2 ι = 1 m C p E 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 | Ξ ı ( ϖ , B q ˜ ( ϖ , c ) ) | p d ϖ 2 p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 p p 2 = C p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 Ξ ( ϖ , B q ˜ ( ϖ , c ) ) p p d ϖ 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 p C p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 2 p 1 T 2 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p .
Thus, we obtain
B q ( t , c ) B q ˜ ( t , c ) p p exp Υ ( ϕ ( ϖ ) ϕ ( 0 ) ) Z 2 p 1 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ˜ ( ϖ , c ) p p exp Υ ( ϕ ( ϖ ) ϕ ( 0 ) ) exp Υ ( ϕ ( ϖ ) ϕ ( 0 ) ) exp Υ ( ϕ ( ϖ ) ϕ ( 0 ) ) + 2 3 p 3 T 1 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 g p 2 + 2 3 p 3 T 2 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p C p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 Z 2 p 1 Γ ( 2 q 1 ) Υ B q ( t , c ) B q ˜ ( t , c ) Υ p + 2 3 p 3 T 1 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 g p 2
+ 2 3 p 3 T 2 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p C p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 .
So
( 1 Z 2 p 1 Γ ( 2 q 1 ) Υ ) B q ( t , c ) B q ˜ ( t , c ) Υ p 2 3 p 3 T 1 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 g p 2 + 2 3 p 3 T 2 p e s s s u p t [ 0 , g ] B q ˜ ( ϖ , c ) p p + γ p C p 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ p 2 .
Now we prove
l i m q ˜ q s u p t [ 0 , g ] 0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ = 0 .
To see this note
0 t A ( t , ϖ , q , q ˜ , ϕ ) 2 d ϖ = 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 Γ 2 ( q ) ϕ ( ϖ ) 2 d ϖ + 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q ˜ 2 Γ 2 ( q ˜ ) ϕ ( ϖ ) 2 d ϖ 2 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q + q ˜ 2 Γ ( q ) Γ ( q ˜ ) ϕ ( ϖ ) 2 d ϖ sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 Γ 2 ( q ) ϕ ( ϖ ) d ϖ + sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q ˜ 2 Γ 2 ( q ˜ ) ϕ ( ϖ ) d ϖ 2 sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q + q ˜ 2 Γ ( q ) Γ ( q ˜ ) ϕ ( ϖ ) d ϖ = G ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q 1 ) ( 2 q 1 ) 1 Γ 2 ( q ) + G ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q ˜ 1 ) ( 2 q ˜ 1 ) 1 Γ 2 ( q ˜ ) G 2 ( ϕ ( ϖ ) ϕ ( 0 ) ) ( q + q ˜ 1 ) ( q + q ˜ 1 ) Γ ( q ) Γ ( q ˜ ) .
This therefore demonstrates the necessary outcome. □
Theorem 3. 
For any c , u , we have
B q ( t , c ) B q ( t , u ) | p T c u p , t [ 0 , g ] ,
where B q ( t , c ) is the solution.
Proof. 
We have
B q ( t , c ) B q ( t , u ) = c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) u ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ( ϖ , B q ( ϖ , c ) ) D ( ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d ϖ + 1 Γ ( q ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ( ϖ , B q ( ϖ , c ) ) Ξ ( ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d W ( ϖ ) .
Apply (8) and we have
B q ( t , c ) B q ( t , u ) p p 2 p 1 c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) u ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) p p + 2 2 p 2 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( D ( ϖ , B q ( ϖ , c ) ) D ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d ϖ p p + 2 2 p 2 ( Γ ( q ) ) p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( Ξ ϖ , B q ( ϖ , c ) ) Ξ ϖ , B q ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) p p .
By HI and ( ξ 1 ) .
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( D ( ϖ , B q ( ϖ , c ) ) D ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d ϖ p p = ı = 1 m E ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( D ı ϖ , B q ( ϖ , c ) ) D ı ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d ϖ p ı = 1 m E ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) ( p 2 ) p 1 ϕ ( ϖ ) p 2 p 1 d ϖ p 1 ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | D ı ( ϖ , B q ( ϖ , c ) ) D ı ϖ , B q ( ϖ , u ) ) | ϕ ( ϖ ) 2 d ϖ ) ı = 1 m E ( sup 0 < ϖ t ϕ ( ϖ ) 1 1 p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) ( q 1 ) ( p 2 ) p 1 ϕ ( ϖ ) d ϖ p 1 ( 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | D ı ( ϖ , B q ( ϖ , c ) ) D ı ϖ , B q ( ϖ , u ) ) | ϕ ( ϖ ) 2 d ϖ ) ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) 2 d ϖ . ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) d ϖ = ϝ p 1 T 1 p ϕ ( ϖ ) ϕ ( 0 ) ( p q 2 q + 1 ) ( p 1 ) p 1 p q 2 q + 1 p 1 G 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) d ϖ .
Through ( ξ 1 ) , HI, and BDGI, we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( Ξ ( ϖ , B q ( ϖ , c ) ) Ξ ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d W ( ϖ ) p p = ı = 1 m E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( Ξ ı ( ϖ , B q ( ϖ , c ) ) Ξ ı ϖ , B q ( ϖ , u ) ) ϕ ( ϖ ) d W ( ϖ ) | p ı = 1 m C p E | 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ( ϖ , B q ( ϖ , c ) ) Ξ ı ( ϖ , B q ( ϖ , u ) ) | 2 ϕ ( ϖ ) 2 d ϖ | p 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ( ϖ , B q ( ϖ , c ) ) Ξ ı ( ϖ , B q ( ϖ , u ) ) | p ϕ ( ϖ ) 2 d ϖ 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ p 2 2 ı = 1 m C p E 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 | Ξ ı ( ϖ , B q ( ϖ , c ) ) Ξ ı ( ϖ , B q ( ϖ , u ) ) | p ϕ ( ϖ ) 2 d ϖ sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ p 2 2 G p 2 2 T 2 p C p ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) 2 d ϖ . G p 2 2 T 2 p C p ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) d ϖ . = G p 2 2 T 2 p C p ( ϕ ( ϖ ) ϕ ( 0 ) ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 G 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) d ϖ .
From (39) using (40) and (41), we obtain
B q ( t , c ) B q ( t , u ) p p 2 p 1 c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) u ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) p p + 2 p 1 Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 B q ( ϖ , c ) B q ( ϖ , u ) p p ϕ ( ϖ ) d ϖ .
Now, the Grönwall inequality, gives
B q ( t , c ) B q ( t , u ) p p 2 p 1 exp 2 p 1 Z 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) u ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) p p .
By ([44], [Lemma 7.1.1]), we have
B q ( t , c ) B q ( t , u ) p p 2 p 1 E 2 q 1 2 p 1 Z Γ ( 2 q 1 ) ϕ ( 2 q 1 ) c ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) u ( ϕ ( t ) ϕ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) p p .
Hence,
lim c u B q ( t , c ) B q ( t , u ) p = 0 .

3.2. Regularity

Next, we prove the smoothness of the solution of SPFrDEs.
Theorem 4. 
Let ( ξ 1 ) and ( ξ 2 ) hold. Then, for U > 0 that depends on q , T , γ , p , g , ϕ .
B q ( c , t ) B q ( c , r ) p U | t r | q 1 2 , t , r [ 0 , g ] .
Proof. 
For t > r , we achieve
B q ( t , c ) B q ( r , c ) p p 1 Γ p ( q ) 2 2 2 p r t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ( ϖ , B q ( ϖ , c ) ) ϕ ( ϖ ) d ϖ p p + 1 Γ p ( q ) 2 2 2 p r t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ( ϖ , B q ( ϖ , c ) ) ϕ ( ϖ ) d W ( ϖ ) p p + 1 Γ p ( q ) 2 2 2 p 0 r | ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 | D ( ϖ , B q ( ϖ , c ) ) ϕ ( ϖ ) d ϖ p p + 1 Γ p ( q ) 2 2 2 p 0 r | ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 | Ξ ( ϖ , B q ( ϖ , c ) ) ϕ ( ϖ ) d W p p .
Through HI and BDGI.
Γ p ( q ) 2 2 2 p B q ( t , c ) B q ( r , c ) p p ( p 1 ) p 1 ( p q 1 ) p 1 ( ϕ ( t ) ϕ ( r ) ) 1 q p r t D ( ϖ , B q ( ϖ , c ) ) p p d ϖ + C p r t Ξ ( ϖ , B q ( ϖ , c ) ) p p ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ r t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ p 2 2 + 1 ϕ ( g ) ϕ ( 0 ) 2 p 2 0 r D ( ϖ , B q ( ϖ , c ) ) p p d ϖ 0 r | ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 | 2 ϕ ( ϖ ) 2 d ϖ p 2 + C p 0 r ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 2 Ξ ( ϖ , B q ( ϖ , c ) ) p p ϕ ( ϖ ) 2 d ϖ × 0 r ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 2 ϕ ( ϖ ) 2 d ϖ p 2 2 .
We obtain the following:
D ( ϖ , B q ( ϖ , c ) ) p p 2 p 1 T 1 p B q ( ϖ , c ) ) p p + D ( ϖ , 0 ) p p 2 p 1 T 1 p γ 1 + γ p .
Ξ ( ϖ , B q ( ϖ , c ) ) p p 2 p 1 T 2 p B q ( ϖ , c ) ) p p + Ξ ( ϖ , 0 ) p p 2 p 1 T 2 p γ 1 + γ p .
Furthermore,
0 r ( ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ( ϕ ( r ) ϕ ( ϖ ) ) q 1 ) 2 ϕ ( ϖ ) 2 d ϖ sup 0 < ϖ t ϕ ( ϖ ) 0 r ( ϕ ( t ) ϕ ( ϖ ) ) q 1 ϕ ( r ) ϕ ( ϖ ) q 1 2 ϕ ( ϖ ) d ϖ G 0 r ( ϕ ( r ) ϕ ( ϖ ) ) 2 q 2 ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ = ( ϕ ( t ) ϕ ( r ) ) ( 2 q 1 ) ( 2 q 1 ) + ϕ ( r ) ( 2 q 1 ) ϕ ( t ) ( 2 q 1 ) ( 2 q 1 ) ( ϕ ( t ) ϕ ( r ) ) ( 2 q 1 ) ( 2 q 1 ) .
So,
Γ p ( q ) 2 2 2 p B q ( t , c ) B q ( r , c ) p p ( 2 p 2 ) p 1 ( p q 1 ) p 1 ϕ ( t ) ϕ ( r ) ( 2 q 1 ) p 2 T 1 p γ 1 + γ p ϕ ( g ) ϕ ( 0 ) p 2 + 1 ( 2 q 1 ) p 2 ϕ ( t ) ϕ ( r ) ( 2 q 1 ) p 2 T 2 p γ 1 + γ p 2 p 1 C p + 2 p 1 ( 2 q 1 ) p 1 ϕ ( t ) ϕ ( r ) ( 2 q 1 ) p 2 T 1 p γ 1 + γ p ϕ ( g ) ϕ ( 0 ) p 2 + 1 ( 2 q 1 ) p 2 ϕ ( t ) ϕ ( r ) ( 2 q 1 ) p 2 T 2 p γ 1 + γ p 2 p 1 C p .
Hence,
B q ( t , c ) B q ( r , c ) p U ϕ ( t ) ϕ ( r ) p q 1 2 p ,
where
U p = 2 2 p 2 ( 2 p 2 ) p 1 ( p q 1 ) p 1 T 1 p γ 1 + γ p ϕ ( g ) ϕ ( 0 ) p 2 + 1 ( 2 q 1 ) p 2 T 2 p γ 1 + γ p 2 p 1 C p 1 Γ p ( q ) + 2 2 p 2 2 p 1 ( 2 q 1 ) p 1 T 1 p γ 1 + γ p ϕ ( g ) ϕ ( 0 ) p 2 + 1 ( 2 q 1 ) p 2 T 2 p γ 1 + γ p 2 p 1 C p Γ p ( q ) .
Thus, we obtain the following:
lim r t B q ( t , c ) B q ( r , c ) p = 0 .

4. Averaging Principle

Now, we establish generalized results in the p th moment concerning the AP for SPFrDEs within the framework of the ϕ -HFrD.
Lemma 5. 
By utilizing ξ 4 and ξ 5 , we have
Ξ ˜ ( A , ν ) p T 6 1 + A p + ν p ,
where T 6 = 2 p 1 D 2 g 1 + 6 p 1 T 4 p .
Proof. 
By ξ 4 , ξ 5 and (8).
Ξ ˜ ( A , ν ) p Ξ ( t , A , ν ) Ξ ˜ ( A , ν ) p + 2 p 1 Ξ ( t , A , ν ) p 2 p 1 2 p 1 D 2 g 1 1 + A p + ν p + 2 p 1 T 4 p ( 1 + A + ν ) p D 2 g 1 2 p 1 + 6 p 1 T 4 p 1 + A p + ν p .
Now, we prove the time-scale change property to obtain the standard form for the AP of (4).
Lemma 6. 
Assume t = φ , then
T q , a , ϕ H f ( φ ) = T t q , a , ϕ ˜ H f ( t ) .
Proof. 
From (2), we have
T q , a , ϕ H f ( φ ) = 1 Γ ( a ( 1 q ) ) 0 d d ϖ ϕ ( ϖ ) ( ϕ ( ) ϕ ( ϖ ) ) a ( 1 q ) 1 1 d d ϖ ϕ ( ϖ ) d d ϖ d ϖ 1 Γ ( ( 1 a ) ( 1 q ) ) 0 ϕ ( ϖ ) ( ϕ ( ) ϕ ( ϖ ) ) ( 1 a ) ( 1 q ) 1 f ( φ ϖ ) d ϖ .
Let φ ϖ = θ , ϖ = θ φ , and by the chain rule d d ϖ = d d θ . d θ d ϖ = d d θ . d d ϖ ( φ ϖ ) = φ d d θ .
So, we have
T q , a , ϕ H f ( φ ) = 1 Γ ( a ( 1 q ) ) 0 φ φ d d θ ϕ ( θ φ ) ( ϕ ( ) ϕ ( θ φ ) ) a ( 1 q ) 1 1 φ d d θ ϕ ( θ φ ) φ d d θ 1 Γ ( ( 1 a ) ( 1 q ) ) 0 φ φ d d θ ϕ ( θ φ ) ( ϕ ( ) ϕ ( θ φ ) ) ( 1 a ) ( 1 q ) 1 f ( θ ) d θ φ d θ φ .
From above, we have φ = t and = t φ
T q , a , ϕ H f ( φ ) = 1 Γ ( a ( 1 q ) ) 0 t d d θ ϕ ( θ φ ) ( ϕ ( t φ ) ϕ ( θ φ ) ) a ( 1 q ) 1 1 d d θ ϕ ( θ φ ) d d θ 1 Γ ( ( 1 a ) ( 1 q ) ) 0 t d d θ ϕ ( θ φ ) ( ϕ ( t φ ) ϕ ( θ φ ) ) ( 1 a ) ( 1 q ) 1 f ( θ ) d θ d θ .
ϕ ( θ φ ) = ϕ ˜ ( θ ) and ϕ ( t φ ) = ϕ ˜ ( t ) or, equivalently,
T q , a , ϕ H f ( φ ) = 1 Γ ( a ( 1 q ) ) 0 t d d θ ϕ ˜ ( θ ) ( ϕ ˜ ( t ) ϕ ˜ ( θ ) ) a ( 1 q ) 1 1 d d θ ϕ ˜ ( θ ) d d θ 1 Γ ( ( 1 a ) ( 1 q ) ) 0 t d d θ ϕ ˜ ( θ ) ( ϕ ˜ ( t ) ϕ ˜ ( θ ) ) ( 1 a ) ( 1 q ) 1 f ( θ ) d θ d θ .
So, we have the following result:
T q , a , ϕ H f ( φ ) = T t q , a , ϕ ˜ H f ( t ) .
Remark 1. 
For ϕ ( t ) = t and a = 1 , our established time-scale change property aligns with CFD. Similarly, for ϕ ( t ) = t and a = 0 , it aligns with the Riemann–Liouville fractional operator. When ϕ ( t ) = ln ( t ) with a = 0 , and ϕ ( t ) = ln ( t ) with a = 1 , the formulation corresponds to the Hadamard and Caputo–Hadamard fractional operators, respectively.
Now, we establish the result regarding the AP of SPFrDEs for the generalized case. For this, first consider the following:
{ T t q , a , ϕ H f ( t ) = D ( t ε , f ( t ) , f ( t s ) ) + Ξ ( t ε , f ( t ) , f ( s t ) ) d W ( t ) d t , I 0 + ( 1 q ) ( 1 a ) , ϕ f ( 0 ) = c .
Utilizing t ε = Θ , Lemma 6 in (46):
T t q , a , ϕ ˜ H f ( ε Θ ) = D ( Θ , f ( ε Θ ) , f ( s ε Θ ) ) + Ξ ( Θ , f ( ε Θ ) , f ( s ε Θ ) ) d W ( ε Θ ) ε d Θ .
Hence
T t q , a , ϕ ˜ H f ε ( Θ ) = D ( Θ , f ε ( Θ ) , f ε ( s Θ ) ) + ε 1 2 Ξ ( Θ , f ε ( Θ ) , f ε ( s Θ ) ) d W ( Θ ) d Θ .
So, we obtain
T t q , a , ϕ ˜ H f ε ( t ) = D t , f ε ( t ) , f ε ( s t ) + ε 1 2 Ξ t , f ε ( t ) , f ε ( s t ) d W ( t ) d t , I 0 + ( 1 q ) ( 1 a ) , ϕ ˜ f ε ( 0 ) = c .
Thus, (47) can be expressed integrally as
f ε ( t ) = c ( ϕ ˜ ( t ) ϕ ˜ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ϕ ˜ ( ϖ ) ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) 1 q D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) d ϖ + ε 1 2 1 Γ ( q ) 0 t ϕ ˜ ( ϖ ) ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) 1 q Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) d W ( ϖ ) ,
when ε ( 0 , ε 0 ] with fixed point ε 0 . From (48), we have
f ε * ( t ) = c ( ϕ ˜ ( t ) ϕ ˜ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ϕ ˜ ( ϖ ) ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) 1 q D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) d ϖ + ε 1 2 1 Γ ( q ) 0 t ϕ ˜ ( ϖ ) ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) 1 q Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) d W ( ϖ ) ,
where D ˜ : R ϰ × R ϰ R ϰ , Ξ ˜ : R ϰ × R ϰ R ϰ × b .
Theorem 5. 
When ( ξ 3 ) to ( ξ 5 ) are valid. When > 0 , ϱ > 0 , and ε 1 0 , ε 0 with η ( 0 , q p p 2 ) , then
E sup t [ 0 , ϱ ε η ] f ε ( t ) f ε * ( t ) p , ε ( 0 , ε 1 ] .
Proof. 
Using (48) and (49),
f ε ( t ) f ε * ( t ) = c ( ϕ ˜ ( t ) ϕ ˜ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) c ( ϕ ˜ ( t ) ϕ ˜ ( 0 ) ) ( 1 q ) ( 1 a ) Γ ( a ( 1 q ) + a ) + 1 Γ ( q ) 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ + ε 1 2 1 Γ ( q ) 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) .
Via Jensen’s inequality (JI), we have
f ε ( t ) f ε * ( t ) p 2 p 1 1 Γ ( q ) 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ p + 2 p 1 ε 1 2 1 Γ ( q ) 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) p 1 Γ p ( q ) 2 p 1 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ p + 1 Γ p ( q ) 2 p 1 ε p ( 1 2 ) 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) p .
Utilizing (52) in (50).
E [ sup 0 t ϑ f ε ( t ) f ε * ( t ) p ] 1 Γ p ( q ) 2 p 1 E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ p + 1 Γ p ( q ) 2 p 1 ε p ( 1 2 ) E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) p = j 1 + j 2 .
From j 1
j 1 1 Γ p ( q ) 2 2 p 2 E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ p + 1 Γ p ( q ) 2 2 p 2 E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d ϖ p = j 11 + j 12 .
By utilizing HI, JI, and ( ξ 3 ) on j 11 :
j 11 1 Γ p ( q ) 2 2 p 2 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p p 1 ( ϕ ˜ ( ϖ ) ) p p 1 d ϖ p 1 E sup 0 t ϑ 0 t D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) p d ϖ 1 Γ p ( q ) 2 2 p 2 sup 0 < ϖ ϑ ϕ ˜ ( ϖ ) 1 p 1 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p p 1 ϕ ˜ ( ϖ ) d ϖ p 1 E sup 0 t ϑ 0 t D ϖ , f ε ( ϖ ) , f ε ( s ϖ ) D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) p d ϖ 1 Γ p ( q ) 2 3 p 3 p 1 T 3 p ( ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ) ( q p 1 ) p 1 p 1 p 1 q p 1 p 1 E sup 0 t ϑ 0 t f ε ( ϖ ) f ε * ( ϖ ) p d ϖ + E sup 0 t ϑ 0 t f ε ( s ϖ ) f ε * ( s ϖ ) p d ϖ = Y 11 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) ( 0 ϑ E sup 0 ρ ϖ f ε ( ρ ) f ε * ( ρ ) p d ϖ + 0 ϑ E sup 0 ρ ϖ f ε ( ρ s ) f ε * ( ρ s ) p d ϖ ) ,
where Y 11 = 1 Γ p ( q ) 2 3 p 3 T 3 p p 1 q p 1 p 1 p 1 .
From j 12 by applying HI, JI, and ( ξ 5 ) :
j 12 1 Γ p ( q ) 2 2 p 2 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p p 1 ϕ ˜ ( ϖ ) p p 1 d ϖ p 1 E sup 0 t ϑ 0 t D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) p d ϖ 1 Γ p ( q ) 2 2 p 2 sup 0 < ϖ t ϕ ˜ ( ϖ ) 1 p 1 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p p 1 ϕ ˜ ( ϖ ) d ϖ p 1 E sup 0 t ϑ 0 t D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) D ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) p d ϖ p 1 1 Γ p ( q ) 2 2 p 2 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) p 1 p 1 p 1 q p 1 p 1 D 1 ( ϑ ) ϑ 1 + E f ε * ( ϖ ) p + E f ε * ( s ϖ ) p = Y 12 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) ,
where Y 12 = ϑ p 1 1 Γ p ( q ) 2 2 p 2 p 1 q p 1 p 1 D 1 ( ϑ ) 1 + E f ε * ( ϖ ) p + E f ε * ( s ϖ ) p .
The following is provided by j 2 via JI:
j 2 1 Γ p ( q ) 2 2 p 2 ε p ( 1 2 ) E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) p + 1 Γ p ( q ) 2 2 p 2 ε 1 2 ) E sup 0 t ϑ 0 t ( ϕ ˜ ( t ) ϕ ˜ ( ϖ ) ) q 1 Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) ϕ ˜ ( ϖ ) d W ( ϖ ) p = j 21 + j 22 .
By employing ( ξ 3 ) , HI, and BDGI on j 21 :
j 21 1 Γ p ( q ) 2 2 p 2 ε p ( 1 2 ) 2 ( p 1 ) 1 p p p + 1 p 2 E 0 ϑ ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) 2 q 2 Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) 2 ( ϕ ˜ ( ϖ ) ) 2 d ϖ p 2 1 Γ p ( q ) 2 2 p 2 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 p p + 1 2 ( p 1 ) 1 p p 2 E 0 ϑ ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ( q 1 ) p Ξ ϖ , f ε ( ϖ ) , f ε ( s ϖ ) Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) p ϕ ˜ ( ϖ ) p d ϖ 1 Γ p ( q ) 2 3 p 3 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 T 3 p p p + 1 2 ( 1 p ) p 1 p 2 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p E sup 0 ρ ϖ f ε ( ρ ) f ε * ( ρ ) p + f ε ( ρ s ) f ε * ( ρ s ) p ϕ ˜ ( ϖ ) p d ϖ 1 Γ p ( q ) 2 3 p 3 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 T 3 p p p + 1 2 ( 1 p ) p 1 p 2 sup 0 < ϖ ϑ ϕ ˜ ( ϖ ) p 1 0 ϑ ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ( q 1 ) p E sup 0 ρ ϖ f ε ( ρ ) f ε * ( ρ ) p + f ε ( ρ s ) f ε * ( ρ s ) p ϕ ˜ ( ϖ ) d ϖ = Y 21 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 ( 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p E sup 0 ρ ϖ f ε ( ρ ) f ε * ( ρ ) p ϕ ˜ ( ϖ ) d ϖ + 0 ϑ ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p E sup 0 ρ ϖ f ε ( ρ s ) f ε * ( ρ s ) p ϕ ˜ ( ϖ ) d ϖ ,
where Y 21 = 2 3 p 3 T 3 p p p + 1 2 ( p 1 ) p 1 p 2 1 Γ p ( q ) Y and Y = sup 0 < ϖ ϑ ϕ ˜ ( ϖ ) ( p 1 ) .
Utilizing HI and BDGI on j 22 :
j 22 1 Γ p ( q ) ε p ( 1 2 ) 2 2 p 2 2 ( p 1 ) 1 p p p + 1 p 2 E 0 ϑ D ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) Ξ ˜ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) 2 ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) 2 q 2 ϕ ˜ ( ϖ ) 2 d ϖ p 2 1 Γ p ( q ) 2 2 p 2 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 2 ( p 1 ) p 1 p p + 1 p 2 E [ 0 ϑ ( ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) p + Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) p ϕ ˜ ( ϖ ) p d ϖ ] 1 Γ p ( q ) 2 2 p 2 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 2 ( p 1 ) p 1 p p + 1 p 2 E [ sup 0 < ϖ ϑ ϕ ˜ ( ϖ ) ( p 1 ) 0 ϑ ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p Ξ ϖ , f ε * ( ϖ ) , f ε * ( s ϖ ) p + Ξ ˜ f ε * ( ϖ ) , f ε * ( s ϖ ) p ϕ ˜ ( ϖ ) d ϖ 1 Γ p ( q ) 2 3 p 3 3 p 1 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 T 4 p T 4 p + T 6 p ( ( q 1 ) p + 1 ) Y 2 ( p 1 ) 1 p p p + 1 p 2 1 + E [ f ε * ( ϖ ) p ] + E [ f ε * ( s ϖ ) p ] = Y 22 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 ,
here
Y 22 = 2 3 p 3 3 p 1 T 4 p T 4 p + T 6 p 1 ( ( q 1 ) p + 1 ) Y 2 ( p 1 ) 1 p p p + 1 p 2 1 + E [ f ε * ( ϖ ) p ] + E [ f ε * ( s ϖ ) p ] 1 Γ p ( q ) .
From (54), (59), and (53).
E sup 0 t ϑ f ε ( t ) f ε * ( t ) p Y 12 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) + Y 22 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 + 0 ϑ ( Y 11 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) + Y 21 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p ϕ ˜ ( ϖ ) E sup 0 ρ ϖ f ε ( ρ ) f ε * ( ρ ) p d ϖ + 0 ϑ ( Y 11 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) + Y 21 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) p 2 1 ϕ ˜ ( ϑ ) ϕ ˜ ( ϖ ) ) ( q 1 ) p ϕ ˜ ( ϖ ) E sup 0 ρ ϖ f ε ( ρ s ) f ε * ( ρ s ) p d ϖ .
From (60), we have
E [ sup 0 t ϑ f ε ( t ) f ε * ( t ) p ] Y 12 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) + Y 22 ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 exp 2 Y 11 ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( q p 1 ) ϑ + 2 Y 21 ( ( q 1 ) p + 1 ) ε p ( 1 2 ) ϕ ˜ ( ϑ ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 .
So, for ϱ > 0 , η ( 0 , q p p 2 ) , and t 0 , ϱ ε η [ 0 , g ] , we have
E sup 0 t ϱ ε η f ε ( t ) f ε * ( t ) p A ε 1 η ,
where
A = ε η 1 Y 12 ϕ ˜ ( ϱ ε η ) ϕ ˜ ( 0 ) ( q p 1 ) + Y 22 ε p ( 1 2 ) ϕ ˜ ( ϱ ε η ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 exp 2 Y 11 ϕ ˜ ( ϱ ε η ) ϕ ˜ ( 0 ) ( q p 1 ) ϱ ε η + 2 Y 21 ( ( q 1 ) p + 1 ) ε p ( 1 2 ) ϕ ˜ ( ϱ ε η ) ϕ ˜ ( 0 ) ( ( q 1 ) p + 1 ) + p 2 1 .
This concludes the proof. □
Corollary 1. 
Suppose that the assumptions ( ξ 3 ) to ( ξ 4 ) are satisfied. When 1 > 0 and ε 1 0 , ε 0 , η ( 0 , q p p 2 ) , and ϱ > 0 , then ε 0 , ε 1 , we have:
lim ε 0 P sup t [ 0 , ϱ ε η ] f ε ( t ) f ε * ( t ) > 1 = 0 .
Proof. 
For 1 > 0 by the Chebyshev–Markov inequality and Theorem 5,
P sup t [ 0 , ϱ ε η ] f ε ( t ) f ε * ( t ) > 1 1 1 2 E sup t [ 0 , ϱ ε η ] f ε ( t ) f ε * ( t ) 2 A ε 1 η 1 2 0 as ε 0 .

5. Numerical Problems

To better understand the theoretical results established in this research, we present numerical problems along with graphical comparisons of the original and averaged solutions. The Figure 1, Figure 2, Figure 3 and Figure 4 show that the solutions of the original system and the average system overlap, demonstrating the effectiveness of our research study.
Problem 1. 
Take the system
T t 0.8 , a , ϕ ˜ H f ε ( t ) = 6 sin 2 ( t ) f ε ( t ) + f ε ( t ) cos 2 ( 1 2 t ) + 3 ε 1 2 f ε ( t ) cos 2 ( t ) sin ( f ε ( t ) ) d W ( t ) d t , t [ 0 , π ] , I 0 + ( 1 0.8 ) ( 1 0.85 ) , t 1 2 f ( 0 ) = c ,
where q = 0.8 , s = 1 2 , and
D ( t , f ( t ) , f ( t s ) ) = 6 sin 2 ( t ) f ε ( t ) + f ε ( t ) cos 2 1 2 t , Ξ ( t , f ( t ) , f ( t s ) ) = 3 f ε ( t ) cos 2 ( t ) sin ( f ε ( t ) ) .
The criteria of the EU are fulfilled by 6 sin 2 ( t ) f ε ( t ) + f ε ( t ) cos 2 1 2 t and 3 f ε ( t ) cos 2 ( t ) sin ( f ε ( t ) ) .
The D and Ξ are shown by the following expressions:
D ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 6 sin 2 ( t ) f ε ( t ) + f ε ( t ) cos 2 1 2 t d t = 7 2 f ε ( t ) , Ξ ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 3 f ε ( t ) cos 2 ( t ) sin ( f ε ( t ) ) d t = 3 2 f ε ( t ) sin ( f ε ( t ) ) .
Hence
T t 0.80 , a , ϕ ˜ f ε * ( t ) = 7 2 f ε ( t ) + 3 2 ε 1 2 f ε ( t ) sin ( f ε ( t ) ) d W ( t ) d t , I 0 + ( 1 0.80 ) ( 1 0.85 ) , t 1 2 f ( 0 ) = c .
Problem 2. 
Consider SPFrDEs:
T t 0.95 , a , ϕ ˜ H f ε ( t ) = 3 sin f ε ( 1 2 t ) sin 2 ( t ) f ε ( t ) + ε 1 2 sin f ε ( t ) cos f ε ( t ) d W ( t ) d t , t [ 0 , π ] , I 0 + ( 1 0.95 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c ,
where q = 0.95 , s = 1 2 , and
D ( t , f ( t ) , f ( t s ) ) = 3 sin f ε ( 1 2 t ) sin 2 ( t ) f ε ( t ) , Ξ ( t , f ( t ) , f ( t s ) ) = sin f ε ( t ) cos f ε ( t ) .
The criteria of EU are fulfilled by 3 sin f ε ( t ) sin 2 ( t ) f ε ( t ) and sin f ε ( t ) cos f ε ( t ) .
So,
D ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 3 sin f ε ( 1 2 t ) sin 2 ( t ) f ε ( t ) d t = 3 2 sin f ε ( 1 2 t ) f ε ( t ) , Ξ ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π sin f ε ( t ) cos f ε ( t ) d t = sin f ε ( t ) cos f ε ( t ) .
Thus,
T t 0.95 , a , ϕ ˜ f ε * ( t ) = 3 2 sin f ε ( 1 2 t ) f ε ( t ) + ε 1 2 sin f ε ( t ) cos f ε ( t ) d t , I 0 + ( 1 0.95 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c .
Problem 3. 
Consider SPFrDEs:
T t 0.9 , a , ϕ ˜ H f ε ( t ) = 1 3 f ε ( 1 4 t ) cos ( f ε ( t ) sin f ε ( t ) + 3 π 4 ε 1 2 sin 3 t cos f ε ( t ) sin f ε ( t ) f ε ( t ) d W ( t ) d t , t [ 0 , π ] , I 0 + ( 1 0.90 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c ,
where q = 0.9 , s = 1 4 , and
D ( t , f ( t ) , f ( t s ) ) = 1 3 f ε ( 1 4 t ) cos f ε ( t ) sin f ε ( t ) , Ξ ( t , f ( t ) , f ( t s ) ) = 3 π 4 sin 3 t cos f ε ( t ) f ε ( t ) sin f ε ( t ) .
The criteria of EU are fulfilled by 1 3 f ε ( 1 4 t ) cos f ε ( t ) sin f ε ( t ) and 3 π 4 sin 3 t cos f ε ( t ) f ε ( t ) sin f ε ( t ) .
The following equations display the D and Ξ averages:
D ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 1 3 f ε ( 1 4 t ) sin f ε ( t ) d q = 1 3 f ε * ( 1 4 t ) sin f ε ( t ) cos f ε ( t ) , Ξ ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 3 π 4 sin 3 t cos f ε ( t ) f ε ( t ) sin f ε ( t ) d q = sin f ε ( t ) cos f ε ( t ) f ε * ( t ) .
Hence
T t 0.9 , a , ϕ ˜ f ε * ( t ) = 1 3 f ε * ( 1 4 t ) sin f ε ( t ) cos f ε ( t ) + ε 1 2 cos f ε ( t ) f ε * ( t ) sin f ε ( t ) d W ( t ) d t , I 0 + ( 1 0.90 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c .
Problem 4. 
Consider SPFrDEs:
T t 0.95 , a , ϕ ˜ H f ε ( t ) = 9 2 sin f ε ( t ) cos f ε ( t ) exp t + ε 1 2 sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) d W ( t ) d t , t [ 0 , π ] , I 0 + ( 1 0.95 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c ,
where q = 0.95 , s = 5 3 , and
D ( t , f ( t ) , f ( t s ) ) = 9 2 sin f ε ( t ) cos f ε ( t ) exp t , Ξ ( t , f ( t ) , f ( t s ) ) = sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) .
The 9 2 sin f ε ( t ) cos f ε ( t ) exp t and sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) satisfies the needs of EU.
Hence,
D ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π 9 2 sin f ε ( t ) cos f ε ( t ) exp t d t = 9 2 π sin f ε ( t ) cos f ε ( t ) ( 1 exp π ) , Ξ ˜ ( f ( t ) , f ( t s ) ) = 1 π 0 π sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) d t = sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) .
Thus, we have the corresponding averaged SPFrDEs
T t 0.95 , a , ϕ ˜ f ε * ( t ) = 9 2 π sin f ε ( t ) cos f ε ( t ) ( 1 exp π ) + ε 1 2 sin f ε ( t ) f ε ( 5 3 t ) cos f ε ( t ) d W ( t ) d t , I 0 + ( 1 0.95 ) ( 1 a ) , ϕ ˜ f ( 0 ) = c .

6. Conclusions

We prove the EU theorem using the contraction mapping principle and demonstrate that the solutions of SPFrDEs have continuous dependence on the fractional and initial values. Additionally, we establish that the solution satisfies the smoothness property by proving the regularity theorem. Using various inequalities, we prove the AP theorem. The primary tools employed in our proofs include the BDGI, JI, and HI. We prove the theorems and lemmas for FFrPSDEs under the ϕ -HFrD.
Our research work is important, for the following reasons: First, by proving the results of the EU, continuous dependence, regularity, and AP in the p th moment, we extend the outcomes for p = 2 . Secondly, we construct theorems and lemmas in the context of ϕ -HFrD. In this way, we generalize the results of Caputo, Riemann–Liouville, and Hadamard and Caputo–Hadamard fractional operators. Third, we take into account SPFrDEs, which are a more widespread subclass of FSDEs.

Author Contributions

Conceptualization, A.M.D. and M.I.L.; methodology, A.M.D. and M.I.L.; software, A.M.D. and M.I.L.; validation, A.M.D. and M.I.L.; formal analysis, A.M.D. and M.I.L.; investigation, A.M.D. and M.I.L.; resources, A.M.D. writing—original draft preparation, A.M.D. and M.I.L.; writing—review and editing, A.M.D. and M.I.L.; visualization, A.M.D. and M.I.L.; funding acquisition, A.M.D. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia (Project No. KFU250687).

Data Availability Statement

No data were generated or analyzed during the current study.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript.
SPFrDEsstochastic pantograph fractional differential equations
HFrDHilfer fractional derivative
APaveraging principle
BDGIBurkholder-Davis-Gundy inequality
FSDEsFractional stochastic differential equations
CFDCaputo fractional derivative
HIHölder’s inequality
JIJensen’s inequality
FDEsfractional differential equations

Appendix A

Appendix A.1

The detailed simplification of (10) is given below: From ( ξ 1 ) , we have
D ϖ , f ( ϖ ) , f ( s ϖ ) p p 2 p 1 D ϖ , f ( ϖ ) , f ( s ϖ ) D ( ϖ , 0 , 0 ) p p + D ( ϖ , 0 , 0 ) p p 2 p 1 ( T 1 p f ( ϖ ) p p + f ( s ϖ ) p p + D ( ϖ , 0 , 0 ) p p ) .
Therefore,
0 t D ϖ , f ( ϖ ) , f ( s ϖ ) p p d ϖ 2 p 1 T 1 p ( e s s s u p ϖ [ 0 , g ] f ( ϖ ) p p + e s s s u p ϖ [ 0 , g ] f ( s ϖ ) p p ) 0 t 1 d ϖ + 2 p 1 0 t D ( ϖ , 0 , 0 ) p p d ϖ 2 p 1 g T 1 p ( f ( ϖ ) H p p + f ( s ϖ ) H p p ) + 2 p 1 0 t D ( ϖ , 0 , 0 ) p p d ϖ .
From (10) and (A2), we get
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d ϖ p p p 1 ϕ ( ϖ ) ϕ ( 0 ) ( q p 1 ) p 1 p 1 p 1 q p 1 p 1 2 p 1 ( T 1 p g ( f ( ϖ ) H p p + f ( s ϖ ) H p p ) + 0 t D ( ϖ , 0 , 0 ) p p d ϖ ) .
Using ( ξ 2 ) , we obtain from (A3) that
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 D ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d ϖ p p p 1 ϕ ( ϖ ) ϕ ( 0 ) ( q p 1 ) p 1 p 1 p 1 q p 1 p 1 2 p 1 ( T 1 p g ( f ( ϖ ) H p p + f ( s ϖ ) H p p ) + g γ p ) .

Appendix A.2

The detailed simplification of (12) is given below: Thus, by using ( ξ 1 ) and ( ξ 2 ) , we have
Ξ ϖ , f ( ϖ ) , f ( s ϖ ) p p 2 p 1 T 2 p f ( ϖ ) p p + f ( s ϖ ) p p + 2 p 1 Ξ ( ϖ , 0 , 0 ) p p 2 p 1 T 2 p f ( ϖ ) p p + f ( s ϖ ) p p + 2 p 1 γ p .
So t [ 0 , g ] , we have
0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) p p ϕ ( ϖ ) 2 d ϖ 2 p 1 T 2 p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ( e s s s u p ϖ [ 0 , g ] f ( ϖ ) p p + e s s s u p ϖ [ 0 , g ] f ( s ϖ ) p p ) ϕ ( ϖ ) 2 d ϖ + 2 p 1 γ p 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) 2 d ϖ 2 p 1 T 2 p sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ( e s s s u p ϖ [ 0 , g ] f ( ϖ ) p p + e s s s u p ϖ [ 0 , g ] f ( s ϖ ) p p ) ϕ ( ϖ ) d ϖ + 2 p 1 γ p sup 0 < ϖ t ϕ ( ϖ ) 0 t ( ϕ ( t ) ϕ ( ϖ ) ) 2 q 2 ϕ ( ϖ ) d ϖ = G 2 p 1 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) ( T 2 p f ( ϖ ) H p p + f ( s ϖ ) H p p + γ p ) .
Therefore, we obtain the following:
0 t ( ϕ ( t ) ϕ ( ϖ ) ) q 1 Ξ ϖ , f ( ϖ ) , f ( s ϖ ) ϕ ( ϖ ) d W ( ϖ ) p p G p 2 2 C p ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) p 2 2 2 p 1 ϕ ( ϖ ) ϕ ( 0 ) ( 2 q 1 ) ( 2 q 1 ) G ( T 2 p f ( ϖ ) H p p + f ( s ϖ ) H p p + γ p ) .

References

  1. Raheem, A.; Alamrani, F.M.; Akhtar, J.; Alatawi, A.; Alshaban, E.; Khatoon, A.; Khan, F.A. Study on Controllability for Ψ-Hilfer Fractional Stochastic Differential Equations. Fractal Fract. 2024, 8, 727. [Google Scholar] [CrossRef]
  2. Lavanya, M.; Vadivoo, B.S.; Nisar, K.S. Controllability Analysis of neutral stochastic differential equation using Ψ-Hilfer fractional derivative with Rosenblatt process. Qual. Theory Dyn. Syst. 2025, 24, 19. [Google Scholar] [CrossRef]
  3. Gokul, G.; Udhayakumar, R. Approximate Controllability Results of Ψ-Hilfer fractional neutral Hemivariational inequalities with infinite delay via almost sectorial operators. Eur. Phys. J. Spec. Top. 2024, 1–19. [Google Scholar] [CrossRef]
  4. Sousa, J.V.D.C.; Kucche, K.D.; De Oliveira, E.C. Stability of Ψ-Hilfer impulsive fractional differential equations. Appl. Math. Lett. 2019, 88, 73–80. [Google Scholar] [CrossRef]
  5. Kucche, K.D.; Mali, A.D. On the Nonlinear Ψ-Hilfer hybrid fractional differential equations. Comput. Appl. Math. 2022, 41, 86. [Google Scholar] [CrossRef]
  6. Montalvo Bonilla, M.; Vera Baca, J.; Torres Ledesma, C.E. Solvability of Ψ-Hilfer fractional differential equations in the space of summable functions. Mediterr. J. Math. 2024, 21, 204. [Google Scholar] [CrossRef]
  7. Lima, K.B.; Vanterler da C. Sousa, J.; De Oliveira, E.C. Ulam–Hyers type stability for Ψ-Hilfer fractional differential equations with impulses and delay. Comput. Appl. Math. 2021, 40, 293. [Google Scholar] [CrossRef]
  8. Abdo, M.S.; Panchal, S.K. Fractional integro-differential equations involving Ψ-Hilfer fractional derivative. Adv. Appl. Math. Mech. 2019, 11, 338–359. [Google Scholar] [CrossRef]
  9. Varun Bose, C.S.; Udhayakumar, R.; Velmurugan, S.; Saradha, M.; Almarri, B. Approximate controllability of Ψ-Hilfer fractional neutral differential equation with infinite delay. Fractal Fract. 2023, 7, 537. [Google Scholar] [CrossRef]
  10. Kilbas, A.A.; Srivastava, H.M.; Trujillo, J.J. Theory and Applications of Fractional Differential Equations; Elsevier: Amsterdam, The Netherlands, 2006; Volume 204. [Google Scholar]
  11. Vanterler da C. Sousa, J.; Capelas de Oliveira, E. On the ψ-Hilfer fractional derivative. Commun. Nonlinear Sci. Numer. Simul. 2018, 60, 72–91. [Google Scholar] [CrossRef]
  12. Umamaheswari, P.; Balachandran, K.; Annapoorani, N. Existence and stability results for Caputo fractional stochastic differential equations with Lévy noise. Filomat 2020, 34, 1739–1751. [Google Scholar] [CrossRef]
  13. Ben, M.A.; Mchiri, L.; Rhaima, M.; Sallay, J. Hyers-Ulam stability of Hadamard fractional stochastic differential equations. Filomat 2023, 37, 10219–10228. [Google Scholar]
  14. Moualkia, S.; Xu, Y. On the existence and uniqueness of solutions for multidimensional fractional stochastic differential equations with variable order. Mathematics 2021, 9, 2106. [Google Scholar] [CrossRef]
  15. Babaei, A.; Banihashemi, S.; Moghaddam, B.P.; Dabiri, A.; Galhano, A. Efficient Solutions for Stochastic Fractional Differential Equations with a Neutral Delay Using Jacobi Poly-Fractonomials. Mathematics 2024, 12, 3273. [Google Scholar] [CrossRef]
  16. Asai, Y.; Kloeden, P.E. Numerical schemes for ordinary delay differential equations with random noise. Appl. Math. Comput. 2019, 347, 306–318. [Google Scholar] [CrossRef]
  17. Ali, A.; Hayat, K.; Zahir, A.; Shah, K.; Abdeljawad, T. Qualitative Analysis of Fractional Stochastic Differential Equations with Variable Order Fractional Derivative. Qual. Theory Dyn. Syst. 2024, 23, 120. [Google Scholar] [CrossRef]
  18. Zhang, X.; Agarwal, P.; Liu, Z.; Peng, H.; You, F.; Zhu, Y. Existence and uniqueness of solutions for stochastic differential equations of fractional-order (q>1) with finite delays. Adv. Differ. Equ. 2017, 2017, 123. [Google Scholar] [CrossRef]
  19. Lavanya, M.; Vadivoo, B.S. Analysis of controllability in Caputo-Hadamard stochastic fractional differential equations with fractional Brownian motion. Int. J. Dyn. Control 2024, 12, 15–23. [Google Scholar] [CrossRef]
  20. Obradović, M.; Milošević, M. Stability of a class of neutral stochastic differential equations with unbounded delay and Markovian switching and the Euler-Maruyama method. J. Comput. Appl. Math. 2017, 309, 244–266. [Google Scholar] [CrossRef]
  21. Yang, H.; Wu, F.; Kloeden, P.E.; Mao, X. The truncated Euler-Maruyama method for stochastic differential equations with Hölder diffusion coefficients. J. Comput. Appl. Math. 2020, 366, 112379. [Google Scholar] [CrossRef]
  22. Muthukumar, P.; Thiagu, K. Existence of solutions and approximate controllability of fractional nonlocal stochastic differential equations of order 1 < q ≤ 2 with infinite delay and Poisson jumps. Differ. Equ. Dyn. Syst. 2018, 26, 15–36. [Google Scholar]
  23. Zou, G.A.; Wang, B. Stochastic Burgers’ equation with fractional derivative driven by multiplicative noise. Comput. Math. Appl. 2017, 74, 3195–3208. [Google Scholar] [CrossRef]
  24. Khasminskij, R.Z. On the principle of averaging the Itov’s stochastic differential equations. Kybernetika 1968, 4, 260–279. [Google Scholar]
  25. Mao, W.; You, S.; Wu, X.; Mao, X. On the averaging principle for stochastic delay differential equations with jumps. Adv. Differ. Equ. 2015, 2015, 70. [Google Scholar] [CrossRef]
  26. Xu, W.; Xu, W.; Lu, K. An averaging principle for stochastic differential equations of fractional order 0 < α < 1. Fract. Calc. Appl. Anal. 2020, 23, 908–919. [Google Scholar]
  27. Guo, Z.; Lv, G.; Wei, J. Averaging principle for stochastic differential equations under a weak condition. Chaos 2020, 30, 1250014. [Google Scholar] [CrossRef] [PubMed]
  28. Liu, J.; Xu, W. An averaging result for impulsive fractional neutral stochastic differential equations. Appl. Math. Lett. 2021, 114, 106892. [Google Scholar] [CrossRef]
  29. Liu, J.; Xu, W.; Guo, Q. Averaging principle for impulsive stochastic partial differential equations. Stoch. Dyn. 2021, 21, 2150014. [Google Scholar] [CrossRef]
  30. Ahmed, H.M.; Zhu, Q. The averaging principle of Hilfer fractional stochastic delay differential equations with Poisson jumps. Appl. Math. Lett. 2021, 112, 106755. [Google Scholar] [CrossRef]
  31. Xu, W.; Xu, W.; Zhang, S. The averaging principle for stochastic differential equations with Caputo fractional derivative. Appl. Math. Lett. 2019, 93, 79–84. [Google Scholar] [CrossRef]
  32. Jing, Y.; Li, Z. Averaging principle for backward stochastic differential equations. Discret. Dyn. Nat. Soc. 2021, 2021, 6615989. [Google Scholar] [CrossRef]
  33. Guo, Z.; Xu, Y.; Wang, W.; Hu, J. Averaging principle for stochastic differential equations with monotone condition. Appl. Math. Lett. 2022, 125, 107705. [Google Scholar] [CrossRef]
  34. Mouy, M.; Boulares, H.; Alshammari, S.; Alshammar, M.; Laskri, Y.; Mohammed, W.W. On averaging principle for Caputo–Hadamard fractional stochastic differential Pantograph equation. Fractal Fract. 2023, 7, 31. [Google Scholar] [CrossRef]
  35. Shen, G.; Wu, J.L.; Yin, X. Averaging principle for fractional heat equations driven by stochastic measures. Appl. Math. Lett. 2020, 106, 106404. [Google Scholar] [CrossRef]
  36. Liu, J.; Zhang, H.; Wang, J.; Jin, C.; Li, J.; Xu, W. A note on averaging principles for fractional stochastic differential equations. Fractal Fract. 2024, 8, 216. [Google Scholar] [CrossRef]
  37. Liu, J.; Wei, W.; Wang, J.; Xu, W. Limit behavior of the solution of Caputo-Hadamard fractional stochastic differential equations. Appl. Math. Lett. 2023, 140, 108586. [Google Scholar] [CrossRef]
  38. Yang, D.; Wang, J.; Bai, C. Averaging principle for Ψ-Caputo fractional stochastic delay differential equations with Poisson jumps. Symmetry 2023, 15, 1346. [Google Scholar] [CrossRef]
  39. Djaouti, A.M.; Khan, Z.A.; Liaqat, M.I.; Al-Quran, A. Existence, uniqueness, and averaging principle of fractional neutral stochastic differential equations in the Lp space with the framework of the Ψ-Caputo derivative. Mathematics 2024, 12, 1037. [Google Scholar] [CrossRef]
  40. Djaouti, A.M.; Liaqat, M.I. Qualitative analysis for the solutions of fractional stochastic differential equations. Axioms 2014, 13, 438. [Google Scholar] [CrossRef]
  41. Albuquerque, N.; Araújo, G.; Pellegrino, D.; Seoane-Sepúlveda, J.B. Hölder’s inequality: Some recent and unexpected applications. Bull. Belg. Math. Soc.-Simon Stevin 2017, 24, 199–225. [Google Scholar] [CrossRef]
  42. Yang, Z.; Zheng, X.; Wang, H. Well-posedness and regularity of Caputo–Hadamard fractional stochastic differential equations. Z. Angew. Math. Phys. 2021, 72, 141. [Google Scholar] [CrossRef]
  43. Kohler, M.; Krzyżak, A.; Walk, H. Estimation of the essential supremum of a regression function. Stat. Probab. Lett. 2011, 81, 685–693. [Google Scholar] [CrossRef]
  44. Henry, D. Geometric Theory of Semilinear Parabolic Equations; Springer: Berlin/Heidelberg, Germany, 2006; Volume 840. [Google Scholar]
Figure 1. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Figure 1. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Fractalfract 09 00134 g001
Figure 2. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Figure 2. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Fractalfract 09 00134 g002
Figure 3. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Figure 3. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Fractalfract 09 00134 g003
Figure 4. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Figure 4. Red: original equation; blue: averaged equation for ϵ = 0.001 .
Fractalfract 09 00134 g004
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Djaouti, A.M.; Liaqat, M.I. Theoretical Results on the pth Moment of ϕ-Hilfer Stochastic Fractional Differential Equations with a Pantograph Term. Fractal Fract. 2025, 9, 134. https://doi.org/10.3390/fractalfract9030134

AMA Style

Djaouti AM, Liaqat MI. Theoretical Results on the pth Moment of ϕ-Hilfer Stochastic Fractional Differential Equations with a Pantograph Term. Fractal and Fractional. 2025; 9(3):134. https://doi.org/10.3390/fractalfract9030134

Chicago/Turabian Style

Djaouti, Abdelhamid Mohammed, and Muhammad Imran Liaqat. 2025. "Theoretical Results on the pth Moment of ϕ-Hilfer Stochastic Fractional Differential Equations with a Pantograph Term" Fractal and Fractional 9, no. 3: 134. https://doi.org/10.3390/fractalfract9030134

APA Style

Djaouti, A. M., & Liaqat, M. I. (2025). Theoretical Results on the pth Moment of ϕ-Hilfer Stochastic Fractional Differential Equations with a Pantograph Term. Fractal and Fractional, 9(3), 134. https://doi.org/10.3390/fractalfract9030134

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