Abstract
This research manuscript aims to study a novel implicit differential equation in the non-singular fractional derivatives sense, namely Atangana-Baleanu-Caputo () of arbitrary orders belonging to the interval (2, 3] with respect to another positive and increasing function. The major results of the existence and uniqueness are investigated by utilizing the Banach and topology degree theorems. The stability of the Ulam-Hyers () type is analyzed by employing the topics of nonlinear analysis. Finally, two examples are constructed and enhanced with some special cases as well as illustrative graphics for checking the influence of major outcomes.
1 Introduction
The derivatives of non-integer orders, or fractional derivatives, are a mathematical concept that extends differentiation beyond integer orders. These types of derivatives have a large domain of applications in numerous fields, including physics, engineering, and finance, for additional details see these manuscripts [1–8]. In the realm of fractional calculus has seen the advent of a fresh fractional operator by Atangana and Baleanu () [9], which is free from singularity kernels. This operator is established through the Mittag-Lefler function in the Caputo and Riemann-Liouville contexts. The non-singular fractional operators are well-behaved and allow for more accurate modeling of the underlying system. The operator can be used to describe phenomena such as diffusion, wave propagation, and viscoelasticity, and has applications in many fields such as image processing, signal analysis, and control theory. Non-singular fractional operators are important tools for researchers and practitioners seeking to understand and manipulate complex systems in a variety of contexts and they have stimulated a great deal of interest among researchers in their applicability to diverse problems, we indicate the readers to these works [10–19] and the references therein. Subsequently, authors of this work [20] popularized the definition to contain differentiation and integration with respect to non-negative, non-decreasing function, leading to the development of the operator. In 2023, Abdeljawad et al. [21] expanded this operator to higher-order fractional derivatives and integrals. Furthermore, this type of fractional derivative is a generalization of the traditional derivative, where the derivative is taken with respect to a function rather than a variable. This type of derivative is commonly used in fractional calculus with various operators to describe complex systems with non-integer order dynamics. In fact, by taking this fractional derivative, the researchers can better model the behavior of these systems and gain a deeper understanding of their underlying dynamics, see for example [22–24] and references cited therein.
An implicit differential equation involving a fractional derivative of an unknown function that appears implicitly in the equation has several benefits, including the ability to model complex systems with memory effects, non-local interactions, and anomalous diffusion. These equations also accurately describe physical phenomena such as transport in porous media or viscoelastic materials [25–28]. In particular, Thabet and Kedim [29] studied a Hilfer fractional snap dynamic system on an infinite interval. Authors [30] discussed stability analysis of fractional pantograph implicit differential equations with initial boundary and impulsive conditions. Also, fractional derivative used to investigate the stability of implicit differential problem by authors [31].
Recently in 2022, Shah et al. [32] used degree theory to establish qualitative results for the following differential equation:
| (1.1) |
Very recently, authors [33] extended the above equation (1.1) to the Caputo fractional order derivative for discussing the qualitative results and some types of stability as in the following form:
| (1.2) |
Inspired by the research mentioned above articles, in this current work, we study the qualitative properties of the solution for implicit fractional differential equation (IFDE) of the following form:
| (1.3) |
where denotes the fractional derivatives of arbitrary order μ ∈ (2, 3] and the function is continuous. Additionally, be a non-decreasing and non-negative function with , such that and Furthermore, and .
In this situation, we would like to indicate that our contributions are interesting and the Eq (1.3) is new in the framework of fractional order derivatives which include derivative as a special case when . Moreover, an approach analysis in this work is different about methods used in these works [32, 33], and the Eq (1.3) covers many problems available in the literature studies, for instance,
(i) the Eq (1.3) reduces to problem (1.1) if μ → 3, and the implicit term omitted;
(ii) the Eq (1.3) returns to problem (1.2) if we replace the operator by with omitting the implicit term.
The remaining parts of this paper are arranged as follows: Sec.2 is devoted to recalling the basic background materials related to fractional calculus and nonlinear analysis. Sec.3 discusses the existence and uniqueness theorems by using . Sec.4 is investigated stability. Finally, Sec.5 is dedicated to testing the effectiveness of main outcomes.
2 Preliminaries
In this situation, we present essential background material. Consider the space of continuous functions denoted by which is Banach space gifted with the norm ‖y‖ = supυ∈[ι,ρ]|y(υ)|.
Definition 2.1 [34] Let and μ > 0, then the equation
is μth order of -Riemann–Liouville fractional integral, where Γ is Gamma function.
Definition 2.2 [21]. The fractional derivatives of with order μ ∈ (m, m + 1], ν = μ − m, m = 0, 1, 2, …, is defined as
where and . If , then . Furthermore, is the Mittag-Leffler function
and Φ(μ) denotes the normalization function endowed by Φ(0) = Φ(1) = 1.
Definition 2.3 [21]. The following relation:
is fractional integral of a function y with order μ ∈ (m, m + 1], ν = μ − m, m = 0, 1, 2, …, where is -Riemann–Liouville fractional integral.
Lemma 2.4 [21]. For μ ∈ (m, m + 1], ν = μ − m, m = 0, 1, 2, …, and and . Then
Lemma 2.5 [21]. For μ ∈ (m, m + 1], ν = μ − m, m = 0, 1, 2, …, ϵ > 0, and with Then,
(i) ;
(ii) .
Now, we about to introduce a definition of the Kuratowski’s measure of noncompactness χ(⋅) as follows:
where , and is a bounded subset of the Banach space Ω. It is clear that [35].
Definition 2.6 [35] Let be bounded and continuous with . Then, will be χ-Lipschitz if ∃ ϵ ≥ 0, so that
As well as, is named as strict χ-contraction when ϵ < 1 holds.
Definition 2.7 [35] A function is χ-condensing if
So, gives χ(B) = 0. Also, is Lipschitz for ϵ > 0 such that
If ϵ < 1, in this case is called a strict contraction.
Lemma 2.8 [35] is χ-Lipschitz with constant ϵ = 0 iff is compact.
Lemma 2.9 [35] A function is χ-Lipschitz with constant ϵ iff is Lipschitz with Lipschitz constant ϵ.
Theorem 2.10 [36] Let be an χ-condensing and
If is a bounded subset contained in Ω, i.e., a constant k > 0 exists with then for all ζ ∈ [0, 1]. Therefore, has a fixed point and the set belongs to Bk(0).
3 Existence and uniqueness analysis
We introduce an equivalent integral fractional equation of the IFDE (1.3). Regarding this, we first derive the following lemma:
Lemma 3.1 Let and . Then, the fractional differential problem:
| (3.1) |
is equivalent to
Proof At the beginning, we apply on both sides of Eq (3.1) and using Lemma 2.4, we get
So, due to the condition y(ι) = 0, we deduce that e0 = 0. Thus, by substituting the value of e0 and by taking the first derivative with respect to a function , we find
and due to the boundary condition , we have e1 = 0, which yields that
Next, by applying the condition one has
which implies that
Hence, we deduce that
Therefore, the proof is finished.
As a consequence of the above lemma, we present the following essential result:
Lemma 3.2 Let and . Then, the IFDE (1.3) has a solution equivalent to
| (3.2) |
Now, to achieve the required existence and uniqueness theorems, according to Lemma 3.2, the solution of the IFDE (1.3) is a fixed point of the operator ℵ: Ω → Ω which is defined as:
| (3.3) |
For working analysis, we state the following conditions:
-
(AS1)There are the constants δ1, δ2, δ3 > 0, such that
for any and υ ∈ J. -
(AS2)There are the constants ℓ1 > 0 and ℓ2 ∈ (0, 1), for any and υ ∈ J, satisfy
For simplicity, we set
Theorem 3.3 Under assumption (AS1) with δ3 ≠ 1. The mapping ℵ: Ω → Ω is continuous and satisfy the growth condition ‖ℵy‖ ≤ Π1 + Π2‖y‖.
Proof We define a bounded ball as . Regarding to show the continuity of ℵ, let us taking the convergence sequence to y in the ball ℧ς as n → ∞. Thus, by continuity of ϖ and by applying Lebesgue dominated convergence theorem, one has
Hence, ℵ is continuous.
Next, regarding to the growth condition, by applying (AS1), we find
| (3.4) |
Since, then
which implies that
| (3.5) |
Therefore, in view of the Eqs (3.4) and (3.5), and taking supremum, one has
Hence, ‖ℵy‖ ≤ Π1 + Π2‖y‖ and this finishes the proof.
Theorem 3.4 Under assumption (AS1) with δ3 ≠ 1, the mapping ℵ: Ω → Ω is compact and consequently is χ-Lipschitz with the Lipschitz’s constant zero.
Proof The boundedness of ℵ implied from Theorem 3.3. It remains to prove that ℵ is an equi-continuous mapping. Therefore, by the assumption (AS1), for any and υ1, υ2 ∈ J with υ1 < υ2, we get
Obviously, |(ℵy)(υ2) − (ℵy)(υ1)| → 0 whenever υ2 → υ1 and thus is equi-continuous. Hence, due to Arzelá-Ascoli theorem, is compact and in view of Lemma 2.8, the mapping ℵ is χ-Lipschitz with the Lipschitz’s constant ϵ = 0.
Theorem 3.5 Under assumption (AS2), the IFDE (1.3) possesses an one solution on condition of
| (3.6) |
Proof Let us take the mapping ℵ as given in (3.3). For any and υ ∈ J, we find
Thus, . Therefore, by condition (3.6), ℵ is contraction mapping and based on the Banach contraction theorem, ℵ possesses a unique fixed point which is a solution of the IFDE (1.3).
Theorem 3.6 Under the assumptions (AS1) and (AS2), the IFDE (1.3) admits a solution such that Π2 < 1. Furthermore, the set containing solutions of the IFDE (1.3) is bounded.
Proof According Theorem 3.5, ℵ is Lipschitz mapping and by Lemma 2.9, ℵ is χ-Lipschitz which implies that ℵ is χ-condensing.
Now, due to Theorem 2.10, it remains to show that the set is bounded, where
For end this, let , therefore for each υ ∈ J for some ζ ∈ [0, 1], and by Theorem 3.3, we can derive that
Thus, which implies that is a bounded set contained in Ω. In view of Theorem 2.10, implies that ℵ has at least one fixed point, which are act solutions of the IFDE (1.3), and consequently contains solutions of the Eq (1.3) is a bounded subset of Ω.
4 Stability analysis
Here, we will discuss the stability of type. So, we need to state the definitions of stability:
Definition 4.1 [37] Let there is a real constant Ξϖ > 0, such that for all ς > 0. Then the IFDE (1.3), is called stable when is satisfying the relation
| (4.1) |
hence there is one function y ∈ Ω satisfying the Eq (1.3), provided
| (4.2) |
Moreover, the solution y ∈ Ω of the Eq (1.3) is called generalized () stable, if there is a function satisfied
| (4.3) |
Remark 4.2 The function satisfying the inequality (4.1), iff there is a function σ ∈ Ω, where
1) |σ(υ)| ≤ ς, υ ∈ [ι, ρ], ς > 0;
2) .
Theorem 4.3 Let the arguments of Theorem 3.5 are satisfied. Then, the solution of IFDE (1.3) is and consequently stable.
Proof Suppose that satisfying the Ineq. (4.1), then by applying (4.2), we get
According to Eq (3.2), one has
| (4.4) |
which gives
| (4.5) |
Next, for , by utilizing Eqs (4.4) and (4.5) and (AS2), we have
which further implies
| (4.6) |
where
Thus, yields that
Hence, the fractional implicit differential problem (1.3) is stable. In addition, there is a non-decreasing function Θ: (0, ∞) → (0, ∞), where Θ(0) = 0, so by (4.6), we find
Therefore, the IFDE (1.3) is stable.
5 Applications
This section concerns the applications of the essential results using two comprehensive examples with illustrative graphics and tables.
Example 5.1 Consider the IFDE as follows:
| (5.1) |
Here, and
Thus, we get
hence, ℓ1 = 0.0065, ℓ2 = 0.0131385. So, we have
Then, according to Theorem 3.5, the IFDE (5.1) has one solution. Furthermore, based on Theorem 4.3 the such solution is stable with
and consequently is stable.
Additionally, Fig 1, represents the graphics of Π3, which are less than 1, and Table 1, shows the computation values of Π3, and Ξϖ, whenever the function , on υ ∈ [1, e], for the problem (5.1). Also, Fig 2, represents the graphics of Π3, which are less than 1, and Table 2, shows the computation values of Π3 whenever the function , and various μ ∈ (2, 3] on υ ∈ [1, e] for problem (5.1).
Fig 1. Shows the values of Π3 < 1, for various functions and υ ∈ [1, e] for problem (5.1).
Table 1. Numerical results of Π3 and Ξϖ at various functions , and on [1, e] for problem 5.1.
| υ | ||||||
|---|---|---|---|---|---|---|
| Π3 < 1 | Ξϖ | Π3 < 1 | Ξϖ | Π3 < 1 | Ξϖ | |
| 1.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
| 1.12450 | 0.0019 | 0.2800 | 0.0008 | 0.1237 | 0.0012 | 0.1752 |
| 1.4900 | 0.0097 | 1.4678 | 0.0041 | 0.6227 | 0.0040 | 0.6047 |
| 1.7350 | 0.0275 | 4.2231 | 0.0116 | 1.7557 | 0.0079 | 1.1861 |
| 1.9800 | 0.0599 | 9.5295 | 0.0256 | 3.9348 | 0.0123 | 1.8612 |
| 2.2250 | 0.1128 | 19.0147 | 0.0499 | 7.8485 | 0.0171 | 2.5959 |
| 2.4700 | 0.1929 | 35.7502 | 0.0896 | 14.7260 | 0.0220 | 3.3688 |
| 2.7150 | 0.3081 | 66.5950 | 0.1529 | 26.9840 | 0.0271 | 4.1664 |
Fig 2. Shows the values of Π3 < 1, for some functions and various μ ∈ (2, 3] for problem (5.1).
Table 2. Numerical results of Π3 at various μ ∈ (2, 3] and some functions on [1, e] for problem 5.1.
| μ | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|
| Π3 at | 0.2870 | 0.2955 | 0.3099 | 0.3308 | 0.3584 | 0.3930 | 0.4349 | 0.4842 | 0.5410 | 0.6055 |
| Π3 at | 0.1470 | 0.1496 | 0.1539 | 0.1598 | 0.1672 | 0.1761 | 0.1862 | 0.1976 | 0.2099 | 0.2232 |
| Π3 at | 0.0278 | 0.0276 | 0.0272 | 0.0266 | 0.0258 | 0.0248 | 0.0236 | 0.0221 | 0.0204 | 0.0186 |
Example 5.2 Consider the IFDE as follows:
| (5.2) |
where, and
Thus, we get
hence, ℓ1 = 0.0123456, ℓ2 = 0.0327538. So, we have
Then, in view of Theorem 3.5, the IFDE (5.2) has one solution. Furthermore, based on Theorem 4.3 the such solution is stable with
and consequently is stable.
Moreover, Fig 3, represents the graphics of Π3, which are less than 1, and Table 3, shows the computation values of Π3, and Ξϖ, whenever the function , on υ ∈ [1, 2], for the problem (5.2). In addition, Fig 4, represents the graphics of Π3, which are less than 1, and Table 4, shows the computation values of Π3 whenever the function , and various μ ∈ (2, 3] on υ ∈ [1, 2] for problem (5.2). According to Fig 4 and Table 4, we observe that Π3 ≥ 1 for some values μ at function , thus for this reason and only at these values we can’t say that the problem (5.2) has one solution.
Fig 3. Shows the values of Π3 < 1, for various functions and υ ∈ [1, 2] of the problem (5.2).
Table 3. Numerical results of Π3 and Ξϖ of some functions , , and , on [1, 2] for problem 5.2.
| υ | ||||||
|---|---|---|---|---|---|---|
| Π3 < 1 | Ξϖ | Π3 < 1 | Ξϖ | Π3 < 1 | Ξϖ | |
| 1.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
| 1.1250 | 0.0006 | 0.0493 | 0.0007 | 0.0558 | 0.0005 | 0.0369 |
| 1.2500 | 0.0039 | 0.3059 | 0.0050 | 0.3974 | 0.0027 | 0.2143 |
| 1.3750 | 0.0126 | 1.0026 | 0.0186 | 1.4848 | 0.0083 | 0.6538 |
| 1.5000 | 0.0313 | 2.5335 | 0.0516 | 4.2628 | 0.0190 | 1.5188 |
| 1.6250 | 0.0668 | 5.6122 | 0.1215 | 10.8329 | 0.0373 | 3.0384 |
| 1.7500 | 0.1297 | 11.6766 | 0.2563 | 26.9974 | 0.0661 | 5.5489 |
| 1.8750 | 0.2358 | 24.1681 | 0.4993 | 78.1367 | 0.1089 | 9.5792 |
| 2.0000 | 0.4086 | 54.1394 | 0.9152 | 845.0222 | 0.1699 | 16.0365 |
Fig 4. Shows the values of Π3 < 1, for some functions and various μ ∈ (2, 3] of problem (5.2).
Table 4. Numerical results of Π3 at various μ ∈ (2, 3] and some functions on [1, 2] for problem 5.2.
| μ | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|
| Π3 at | 0.3002 | 0.3057 | 0.3148 | 0.3273 | 0.3432 | 0.3622 | 0.3841 | 0.4086 | 0.4355 | 0.4645 |
| Π3 at | 0.5479 | 0.5636 | 0.5908 | 0.6298 | 0.6813 | 0.7458 | 0.8237 | 0.9152 | 1.0205 | 1.1398 |
| Π3 at | 0.1550 | 0.1562 | 0.1579 | 0.1601 | 0.1626 | 0.1651 | 0.1676 | 0.1699 | 0.1718 | 0.1732 |
6 Conclusions
This manuscript dealt with a new class of -IFDE (1.3) with higher orders belonging to the interval (2, 3]. The fundamental conditions of the existence and uniqueness of the solution for Eq (1.3) were established by Banach and topology degree theories. Moreover, the stability with its generalized was discussed. Finally, two application examples with illustrative graphics and tables were provided to check the effectiveness of the main results with compare the main parameters.
The results of this study can be employed in new problems as special cases of the main Eq (1.3) by taking various functions of . Furthermore, the -IFDE (1.3) covers some problems are existing in the literature; for instance (i) the Eq (1.3) can be reduced to problem (1.1) if μ → 3 and the implicit term omitted; (ii) the Eq (1.3) can be returned to problem (1.2) if we replace the operator by with omitting the implicit term.
Data Availability
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
Funding Statement
Pontificia Universidad Cat´olica del Ecuador, Proyecto T´ıtulo: “Algunos resultados Cualitativos sobre Ecuaciones diferenciales fraccionales y desigualdades integrales” (Cod UIO2022 to M. V-C). This study is supported via funding from Prince Sattam bin Abdulaziz University project number (PSAU/2024/R/1445 to I. K.).
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Data Availability Statement
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.




