1. Introduction
Fractional differential inclusions and equations have many applications in our life [
1,
2,
3,
4]. Impulsive differential equations and impulsive differential inclusions are suitable models for studying the dynamics of actions in which a sudden change in state occurs. If this change occurs instantaneously, it is called an instantaneous impulse [
5,
6], but if this change continues for a period of time, it is called a non-instantaneous impulse [
7,
8,
9].
There are many definitions for the fractional differential operator, and some of them are particular cases of others. Therefore, it is useful to consider fractional differential equations and fractional differential inclusions that contain a fractional differential operator which includes a large number of other fractional differential operators. This is our goal in this work. Indeed, in this paper, we consider a semilinear differential inclusion involving the w-weighted -Hilfer fractional derivative, (Definition 3, below), which generalizes the concepts of fractional differential operators that were presented by Riemann–Liouville , Caputo , Hadamard , -Riemann–Liouville ,-Caputo , Katugampola , , Hilfer–Hadamard, , Hilfer , Hilfer–Katugampola and -Hilfer derivatives .
Since the mild solution of a differential equation is not required to be continuously differentiable, like the classical solution, the study of the existence of mild solutions to differential equations or differential inclusions has been of interest for decades, especially for semi-linear differential equations and semi-linear differential inclusions. More than thirty years ago, the study of the existence of a mild solution to semi-linear differential Equations and semi-linear differential inclusions containing a fractional differential operator became of interest. Some of these equations contained the Caputo fractional derivative [
10,
11,
12], some involved the Riemann–Liouville fractional differential operator [
13,
14], some contained the Caputo-Hadamard fractional differential operator [
15,
16], some included the Hilfer fractional differential operator of order
in [
17,
18,
19,
20,
21,
22,
23,
24,
25,
26], some contained the Katugampola fractional differential operator [
27], some contained the Hilfer–Katugampola fractional differential operator of order
[
28,
29,
30,
31,
32] and others involved the Hilfer fractional differential operator of order
[
33].
In this article, we will prove the existence of a mild solution to a semi-linear differential inclusion involving the w-weighted -Hilfer fractional differential operator. Because the fractional differential operators introduced by Caputo, Riemann–Liouville, Caputo-Hadamard, Hilfer and Hilfer–Katugampola are special cases of w-weighted -Hilfer fractional differential operators, our work generalizes many of the abovementioned results by replacing the fractional differential operator considered in these papers with the w-weighted -Hilfer fractional differential operator.
In order to formulate the problem, we mention some symbols that will be used during this paper.
- .
- is a Banach space.
- , and .
- and
- is a strictly increasing continuously differentiable function with for any , and is its inverse.
- is a natural, and
-
- , ,.
- is the w-weighted -Hilfer derivative operator of order and of type and with a lower limit at
- is the w-weighted -integral operator of order and with a lower limit at .
- is the infinitesimal generator of a strongly continuous cosine family, where maps E into itself.
- (the family of non-empty, convex and compact subsets of)
- are continuous functions, and are fixed points.
- is the Banach space of absolutely continuous functions from ℑ to E.
In this paper, and by using the properties of
w-weighted
-Laplace transform, we derive at first the formula of a mild solution to the following differential inclusion containing the
w-weighted
-Hilfer fractional derivative order
and of type
with the existence of non-instantaneous impulses in Banach spaces with infinite dimensions:
Then, without assuming the compactness of , we find the sufficient conditions that ensure that the mild solution set of Problem (1) is not empty or compact in the Banach space , which will be defined latter.
To further explain our arguments that clarify our motivation for studying Problem (1) addressed in this manuscript, as well as the importance of our purpose, we state the following: In a very recently published paper, Alsheekhhussain et al. [
34] considered Problem (1) when the operator
is the zero operator. Zhou et al. [
10] and He et al. [
11] investigated the existence of mild solutions to Problem (1) when
and
. Wang et al. [
12] considered Problem (1) when
and
. Thongsalee et al. [
13] proved that solutions for Problem (1) exist; when
is the zero operator,
F is a single-valued function,
and
, Shu et al. [
14] studied Problem (1) in the particular cases
and
Gu et al. [
17] was the first to consider Problem (1) when
,
and
.
Working with the Laplace transform and density function, Gu et al. [
17] was the first to define the mild solution for the semilinear differential equation:
where
is the Hilfer fractional derivative of order
,
is the infinitesimal generator of
-semigroup of linear bounded operators,
and
is a fixed point. Jaiwal et al. [
18] presented the definition of a mild solution for (
2) when
is an almost sectorial operator, and then they found the sufficient conditions that guarantee that the solution exists.
Yang et al. [
19] proved the existence of mild solutions for the non-local semilinear differential equation:
where
,
, and
generates an analytic semigroup of uniformly bounded linear operators. Wang et al. [
20] showed solutions for (
3) with the existence of non-instantaneous impulses and where
f is a multi-valued function and studied the controllability of the problem. Very recently, Elbukhari et al. [
23] proved the existence of a mild solution for Problem (
3), when
is the infinitesimal generator of a compact
-semigroup and
g does not satisfy any assumption such as compactness or Lipschitz continuity, making their findings interesting.
Suechoei et al. [
35] derived the formula of a mild solution for Problem (1) in the particular cases
and
Later on, Asawasamrit et al. [
36] studied non-instantaneous, impulsive differential equations involving the
-Caputo fractional derivative of order
with Riemann–Stieltjes fractional integral boundary conditions.
Sousa et al. [
37] introduced the concept of the
-Hilfer fractional derivative of order
and obtained important results. Kucche et al. [
38] showed that solutions for the following non-linear differential equation involving the
-Hilfer fractional derivative exist:
where
,
,
is the
-Hilfer fractional derivative,
and
In [
39,
40,
41,
42,
43,
44,
45,
46], there are studies on the existence of mild solutions of differential equations and inclusions involving the
-weighted
-Hilfer fractional derivative of order
and of type
in the special case
Very recently, Benial et al. [
47] considered
w-weighted
-Riemann–Liouville differential equation of order
where
For other contributions on weighted fractional boundary value problems, we refer to [
48,
49,
50].
Remark 1. Our work is novel and interesting because:
1- To date, none of the researchers in the field have considered studying semilinear differential equations or semilinear differential inclusions containing the w-weighted Φ-Hilfer fractional derivative of order and of type .
2- Our studied problem is considered with the existence of non-instantaneous impulses and in infinite-dimensional Banach spaces.
3- Our problem contains the w-weighted Φ-Hilfer fractional derivative, which interpolates many fractional differential operators, and hence, it includes the majority of problems cited above.
4- Li et al. [33] derived the representation of mild solutions to Problem (1) in the particular situations when and The following summarizes the focal contributions of our work.
A new class of differential inclusions is formulated, involving the w-weighted -Hilfer differential operator, , of order and of type in Branch spaces with finite dimension, when the linear term is the infinitesimal generator of a strongly continuous cosine family, and the nonlinear term is a multi-valued function
By utilizing both the w-weighted -Laplace transform and w- weighted -convolution, the representation of mild solutions for Problem (1) is derived (Lemma 10 and Definition 12).
Our obtained formula for mild solutions coincides with the formula that was obtained by Li et al. [
33] in the special case
and
(Corollary 1).
The conditions that ensure that the mild solution set for Problem (1) is not empty or compact are obtained (Theorem 1).
This work is a generalization of what was achieved in [
17,
19,
33,
34,
35].
An example is given to show the possibility of applying our results (Example 1).
Our method helps interested researchers to generalize the majority of the aforementioned works to the case where the non-linear term is a multifunction and the space is infinite-dimensional.
Since a large class of fractional differential operators can be obtained from , the works in many results mentioned above can be generalized by replacing the considered fractional differential operator with and making the dimension of the space infinite, and this is considered as a suggestion for future research work as a result of our work.
One can obtain a broad class of fractional differential equations and inclusions as a particular case of Problem (1) (see Remark 1).
We organize our work as follows: in
Section 2, we present definitions and results from previous work that we will need to obtain our results. In the third section, we obtain the relation between Problem (1) and the correlating fractional integral equation and the representation of mild solutions. Moreover, we prove that the mild solution set for Problem (1) is not empty or compact. Finally, an example is presented to clarify the possibility of the application of our results.
2. Preliminaries and Notations
We commence this section by recalling some symbols that will be used later.
For any
, denote by
the Banach space of all Lebesgue measurable functions
f such that
when
, and
when
, where
For any function
, define [
50]
and
Let us consider the Banach spaces:
-, where
-
where
-
and
exists
, where
-, where
-.
-
, where
-, where
The function
which is given by :
is a measure of noncompactness on
where
and
Definition 1 ([
50]).
Let . The w-weighted Riemann–Liouville fractional integral of order α where the lower limit at a of a function in regard to is given by: Lemma 1 ([
50], Theorem 2.4).
Assume and , then . Definition 2 ([
50]).
Let and . The w-weighted Riemann–Liouville fractional derivative whose order where the lower limit at a of a function in regard to is given by:assuming that the right-hand side is well defined. Lemma 2 i- If and , then ii- If and , then One can use similar arguments to the ones used in
([
50], Theorems 3.3–3.6) to prove the next lemma.
Lemma 3. i- If and , then exits almost everywhere andwhere ii- If and , then
iii- If , then
iv- If and such that , then for any Definition 3 ([
50]).
Let and . The w-weighted Caputo fractional derivative of order α where the lower limit at a of a function in regard to to is given by:assuming that the right-hand side is well defined. In the following, we recall some properties for and .
Lemma 4 ([
50], Theorems 4.2–4.5).
i- If and, then for ii- If and , then for iii- , where
As a result of Definitions (1) and (3), we give in the following definition the concept of the w-weighted -Hilfer derivative operator.
Definition 4. The w-weighted Φ-Hilfer derivative of order and of type where the lower limit at a for a function is given bywhere assuming that the right-hand side is well defined. Remark 2. 1- If , then exists and consequently exists for
2- If , then and consequently exists for .
3- Let be such that . Since then, . Therefore, by Lemma 1, (5) and (6), we obtain for Definition 5 ([
51]).
We call a one-parameter family of bounded linear operators which maps the Banach space E into itself a strongly cosine family if and only if- (i)
,
- (ii)
for all ,
- (iii)
The map is continuous for each .
Definition 6 ([
51]).
Let be a strongly cosine family, Then, we call the family , wherea strongly continuous sine family correlated with Lemma 5 ([
51]).
Let be a strongly cosine family on E. Then, the following are true.1- for all ;
2- and are commute for all ;
3- For any is continuous;
4- for all ;
5- for all ;
6- There are positive constants and ς such that for all and Definition 7 ([
51]).
The infinitesimal generator of a strongly cosine family is given bywhere is twice continuously differentiable of Lemma 6. Let A be the infinitesimal generator of a strongly continuous cosine family . Then, for λ with ς, belongs to the resolvent set of and where ς is defined in the sixth item 6 of Lemma 5.
Definition 8 ([
50]).
The weighted Laplace transform for a function is given by Definition 9 ([
50], Definition 5.9).
Theweighted convolution of functions and is given bywhere is the inverse function of Φ; that is, . Definition 10 ([
50]).
A function is considered to be a w-weighted Φ-exponential function if there are positive constants such that . Lemma 7 ([
50], Proposition 5.2, Remark 5.8, Theorem 5.9 and Corollary 5.11).
Let .1- .
3- If and E is a piecewise continuous function on each interval and weighted exponential, then 4- If the weighted Laplace transform of f and h exist for , then 5- Let If is well defined for almost , then Lemma 8 ([
52], Corollary 3.3.1.).
Assume that U is a not empty, closed and convex subset of E and is condensing and with a closed graph, where χ is a non-singular measure of noncompactness defined on subsets of U. Then, Υ has a fixed point. Lemma 9 ([
52], Propostion 3.5.1.).
Assume that U is as in Lemma 8 and is condensing on all bounded subsets of U, where χ is a monotone measure of noncompactness defined on E. If Υ has a closed graph, and the fixed-points set for Υ, is a bounded subset of then it is compact. 3. Non-Emptiness and Compactness of the Mild Solution Set for
(1)
Firstly, by using the properties of the
weighted
Laplace transform, we derive the formula of a mild solution function for Problem (1). For this purpose, we consider the following
w-weighted semilinear differential equation of order
and of type
where
. By applying the operator
on both sides of Equation (
14) and using (
7), we have for
Equation (
15) is called the corresponding integral equation for Problem (
14). In the next lemma, we obtain the formula of a mild solution function for (
14).
Lemma 10. Assume that A is the infinitesimal generator of a strongly continuous cosine family and such that If x satisfies (15), then, for ,where , and .
Proof. Let
be such that
, where
is given as in the sixth item of Lemma 5. Then, using Lemma 6,
is well defined and
Applying the generalized
weighted
Laplace transform, defined by (
9), on both sides of Equation (
15) and using (
10) and (
11), it follows that
In
, replacing
with
, we obtain
Because
, then [
53]
Equations (
22) and (
23) imply that
Replacing
with
,
Replacing
with
and using (
11), (
12) and (
17), we obtain
Since, from (
10),
it yields,
Since
and
by (
13), we have
For
, by arguing as in (
21)–(
23), we can arrive at
Replacing, in (
26),
with
one can obtain
Replacing
in (
27), with
we obtain:
Replacing
with
and using (
17), we get
where
Equations (
20), (
25), (
26) and (
28) give us
By utilizing the
weighted
Laplace transform, we obtain, for any
,
So, (
16) is satisfied. □
As a consequence of Lemma 10, we obtain the next definitions:
Definition 11. A function is called a mild solution for Problem (14) when it satisfies the next fractional integral equation: Definition 12. A function is called a mild solution for Problem (1) if it satisfies the following fractional integral equation:where , , , , and with . Corollary 1. If , and ,∀ then the mild solution function of the following problem:becomeswhere , andand this coincides with Definition (8) in [33]. The next lemma illustrates some properties of .
Lemma 11. Suppose that the operator A satisfies the next condition:
(A) A is the infinitesimal generator of a strongly continuous cosine family , and there is such that sup
Then,
1- For every , every and every , 2- For any Proof. 1- Since sup
, it yields
Since
, it follows that
2- For any
with
we have
□
Lemma 12. For every and every Proof. Then, Equation (
37) is yielded from (
39) and (
41). Now, by (
35), (
37) and assumption (A), we obtain
So, (
38) holds. □
Lemma 13. If , then Proof. In view of
of Lemma 3, (ii) of Lemma 4 and (
38), we have
So, (
41) is true. □
In the next theorem, we demonstrate that the mild solution set for Problem (
4) is not empty or compact.
In addition to condition , assume to be such that:
For any, is measurable and for almost , upper semicontinuous.
There is a function
such that for every
There is
such that for every bounded set
where
is the Hausdorff measure of non-compactness on
For every
,
such that for every
map, every bounded set to a relatively compact subset and for every bounded set
D,
Moreover, there is
with
For any
,
is defined such that it maps bounded sets to relatively compact sets, and there is
with
Hence, Problem (1) has a mild solution assuming that the next inequalities are satisfied.
and
where
Moreover, the set of mild solutions is compact in Banach space
Proof. Let
. Assumptions
and
imply the existence of a measurable function
with
[
52]. We define a multi-valued function ℜ :
(the family of non-empty subsets of
) in the following manner:
means that
where
with
Our aim in the following steps is to show that, by using Lemma 8, the ℜ has a fixed point, and it is clear that this point is a mild solution for Problem (
4).
Step 1. For any , is convex. This is, clearly, achieved since the set of values of F is convex.
Step 2. There exists
such that
, where
. To clarify this, assume that there are
with
,
and
. So, according to (
44), there are
with
and
Let
By (
41),
Moreover, according to the definition of
, we have
This inequality with (
35) leads to
Next, from assumption
and (
35), one obtains for almost
,
For
, the assumption
leads to
Next, let
. Set
It is yielded from (
41) that
Moreover, from the definition of
, (
35) and
, we get,
Next, by arguing as in (
49), one has
Relations (
46), (
47) and (
49)–(
53) give us
Dividing both sides of this inequality and then letting
yields
but this inequality contradicts (
42).
Step 2. The graph of ℜ is closed on
. Let
, with
,
and
. Then, there are
with
45) is fulfilled. From (
49),
is uniformly bounded, and hence, it has a weakly convergent subsequence. We denote it, again, by
to a function
f in
. From Mazur’s lemma, there exists a subsequence of
,
, which converges almost everywhere to
f. For any
, let
Obviously,
is a subsequence of
) and converges to the function
Then,
; moreover, the upper semi-continuity of
implies
,
, and so,
.
Step 3. Let
. For every
and every
, let
and
In this step, our aim is to show that the sets
and
are equicontinuous in the Banach spaces
and
.
Case 1. Suppose that
. Then, there is
with
According to the definition of
there exists
and
with
, such that
Let
and
We have
Due to the continuity of
and (
41),
Moreover, using (
35), we obtain
Next, from (
47), we obtain
Relation (
35) implies that
Again, by (
35), one has
and
Note that assumption
leads to
Then, relations (
35) and (
50) tell us
From (
51), we have
Next, using (
51) and the continuity of
, it follows that
For
, we have
Finally, due to (
36) and (
51), it yields
independently of
Suppose that
. Then, there is
with
Case 2. Let
and
Since
, then due to
,
independently of
v. If
, then
independently of
Case 3. Suppose that . Following the same arguments used in case 1, one can show that is equicontinuous.
As a result of the above discussion, the proof of the results in this step is complete.
Step 4. Let ℧
, where
and
. Then,
is a decreasing sequence of not empty, bounded, convex subsets. In this step, our aim is to show that ℧ is not empty or compact. Using the Cantor intersection property, it remains to be shown that
where
is the measure of noncompactness on
which is defined in the introduction section.
Assume
is fixed and
is arbitrarily small. By Lemma 5 in [
54], one can find a sequence
in
with
where
From Step 3, it yields
where
is the measure of non-compactnes in
E,
and
Since, for any
and any
,
, and since
maps bounded sets into relatively compact sets, it follows that
, and hence inequality (
55) becomes
Let
. Since for any
,
, there are
such that
where
with
In view of
it holds for a.e.
Set
Therefore, from (
35), (
56) and (
57) and the properties of the measure of noncompactness, we obtain
Let
. As above, for any
where
with
Because both
and
map bounded sets to relatively compact sets, it yields
where
As in (
58)
From (
56), (
58) and (
59), one has
Then,
Step 5. By applying the Cantor intersection property, the set ℧ is not empty or compact. Then, the multi-valued function satisfies the assumptions in Lemma 8, and hence, the fixed-points set of the function is not empty. Moreover, Using Lemma 9, the set of fixed points of ℜ is compact in □