^{1}

^{1}

^{2}

Let
*X* endowed with the Hausdorff metric
*H*,
*m*-sensitive, infinitely sensitive, or syndetically transitive.

As we all know, it is difficult to express some real problems using autonomous system, such as chemical problems, financial problems, biological problems, etc. Then, we need to study non-autonomous discrete systems. This research considers the following non-autonomous discrete dynamic system:

x n + 1 = h n ( x n ) , n ∈ ℤ + . (1)

where, h n : X → X is a continuous mapping sequence on compact metric space X with the metric d. ℤ + is the positive integer set. Denote h 1 , ∞ = { h n } n = 1 ∞ . The set-valued discrete dynamic system induced system (1) is expressed as

A n + 1 = h ¯ n ( A n ) , n ∈ ℤ + . (2)

where, h ¯ n : κ ( X ) → κ ( X ) is set-valued mapping sequence induced by h 1 , ∞ as h n ( A ) = { h n ( x ) | x ∈ A } . It is obvious that h ¯ n is continuous mapping sequence. κ ( X ) is the space of all non-empty compact subsets of X endowed with the Hausdorff metric H and the Hausdorff metric on κ ( X ) is defined by

H ( A , B ) = max { sup x ∈ A d ( x , B ) , sup y ∈ B d ( y , A ) }

For any A , B ∈ κ ( X ) .

According to [

B ( x , ε ) = { y ∈ X | d ( x , y ) < ε } ,

B ( A , ε ) = { B ∈ κ ( X ) | H ( A , B ) < ε } ,

e ( A ) = { K ∉ κ ( X ) | K ⊂ A } ,

it is clear that e ( A ) = ϕ if and only if A = ϕ .

Through the study of the mapping sequence h n , we understand how the points in the space X move. However, it is far from enough in demographics, species migration, chemical research and numerical simulation. Sometimes, it is needed to know the movement of a finite number of point in space X. For example, one often iterates at the same time finite points while applying the method of numerical evaluation to the investigation of a chaotic system ( X , h 1 , ∞ ) . At this time, any set of finite points in X is just an element of topological space κ ( X ) . Therefore, it is necessary for us to consider the set-valued mapping sequence h ¯ n related to a single mapping sequence h n . Since 2003, H. R. Flores [

The structure of this paper is as follows. In Section 2, some basic definitions are given. In Section 3, the main results are established and proved.

Throughout this paper, ( X , h 1 , ∞ ) is seen as a non-autonomous discrete dynamical system and ( κ ( X ) , h ¯ 1 , ∞ ) is a set-valued discrete system induced by it. { h n } n = 1 ∞ is a continuous self-map over the metric space ( X , d ) . A set M ⊂ ℕ ( ℕ is the natural number set) is called syndetic [

G ( A , m , n ) = min { d ( h 1 n ( x i ) , h 1 n ( y i ) ) : x i , y i ∈ A , i , j ∈ { 1 , 2 , ⋯ , m } , i ≠ j }

and

S h 1 , ∞ , m ( A , λ ) = { n ∈ ℤ + , thereis x i , y i ∈ A ( i , j ∈ { 1 , 2 , ⋯ , m } , i ≠ j ) suchthat G ( A , m , n ) ≥ λ }

where, m , n ∈ ℤ + , A is any nonempty open subset in X.

For any δ > 0 and any non-empty open subset A , B ⊂ X , define

N h 1 , ∞ ( A , δ ) = { n ∈ ℕ : thereis x , y ∈ A with d ( h 1 n ( x ) , h 1 n ( y ) ) > δ }

N h 1 , ∞ ( A , B ) = { n ∈ ℕ : h 1 n ( A ) ∩ B ≠ φ }

Definition 2.1 [

Definition 2.2 Let ( X , h 1 , ∞ ) be a given non-autonomous dynamical system and F a given Furstenberg family.

1) The system ( X , h 1 , ∞ ) is F -sensitive [

2) The system ( X , h 1 , ∞ ) is F -transitive if for any nonempty open subsets A , B of X, N h 1 , ∞ ( A , B ) ∈ F ;

3) The system ( X , h 1 , ∞ ) is ( F 1 , F 2 ) -sensitive [

{ k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y ) ) > δ } ∈ F 2

and

{ k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y ) ) < δ } ∈ F 1

for any δ > 0 ;

4) The system ( X , h 1 , ∞ ) is F -accessible if for any ε > 0 and any two nonempty open subsets A , B ⊂ X , there are two points x ∈ A and y ∈ B such that

{ k : d ( h 1 k ( x ) , h 1 k ( y ) ) < ε } ∈ F ;

5) The system ( X , h 1 , ∞ ) is F -weakly mixing if for all nonempty open subsets A i , B i , i = 1 , 2 of X such that

{ k : h 1 k ( A 1 ) ∩ B 1 ≠ φ and h 1 k ( A 2 ) ∩ B 2 ≠ φ } ∈ F

6) The system ( X , h 1 , ∞ ) is F -m-sensitive if there is a real number λ > 0 such that for any nonempty open subset A of X, there are m points x 1 , x 2 , ⋯ , x m ; y 1 , y 2 , ⋯ , y m ∈ A and n ∈ ℕ such that S h 1 , ∞ , m ( A , λ ) ∈ F ;

7) The system ( X , h 1 , ∞ ) is syndetically transitive [

8) The system ( X , h 1 , ∞ ) is infinitely sensitive [

lim sup n → ∞ d ( h n ( x ) , h n ( y ) ) ≥ η .

This section will show the relationship between h 1 , ∞ and h ¯ 1 , ∞ about F -sensitivity, F -sensitivity, F -transitivity, F -accessible, F -weakly mixing, F -m-sensitivity, infinitely sensitivity and syndetically transitivity.

Lemma 3.1 [

1) if A is a nonempty open subset of X, then e ( A ) is a nonempty open subset of κ ( X ) ;

2) e ( A ∩ B ) = e ( A ) ∩ e ( B ) ;

3) h ¯ ( e ( A ) ) ⊂ e ( h ( A ) ) ;

4) h ¯ n = h n ¯ .

Theorem 3.2 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is F -sensitive, then h 1 , ∞ is F -sensitive.

Proof. Let U be a nonempty open subset of X, the e ( U ) be a nonempty open subset of κ ( X ) . Since h ¯ 1 , ∞ is F -sensitive with the sensitive constant λ > 0 , then N h ¯ 1 , ∞ ( e ( U ) , λ ) ∈ F . Let k ∈ N h ¯ 1 , ∞ ( e ( U ) , λ ) ∈ F , by the definition, there exist K 1 , K 2 ∈ e ( U ) with H ( h ¯ 1 k ( K 1 ) , h ¯ 1 k ( K 2 ) ) ≥ λ . Now, let x ∈ U , taking K 1 = { x } ∈ e ( U ) . Then

H ( h ¯ 1 k ( { x } ) , h ¯ 1 k ( K 2 ) ) = H ( h ¯ 1 k ( x ) , h ¯ 1 k ( K 2 ) ) ≥ λ .

Hence,

H ( h ¯ 1 k ( x ) , h ¯ 1 k ( K 2 ) ) = sup y ∈ K 2 d ( h 1 k ( x ) , h 1 k ( y ) ) ≥ λ

According to the compactness of K 2 and the continuity of h ¯ n ( n ∈ Ν ) , there exists y 0 ∈ K 2 such that

H ( h ¯ 1 k ( { x } ) , h ¯ 1 k ( K 2 ) ) = d ( h 1 k ( x ) , h 1 k ( y 0 ) ) ≥ λ ,

that is for any U ⊂ X , there exist x , y 0 ∈ U such that k ∈ N h 1 , ∞ ( U , λ ) ∈ F and hence N h ¯ 1 , ∞ ( e ( U ) , λ ) ⊂ N h 1 , ∞ ( U , λ ) ∈ F .

Thus, h 1 , ∞ is F -sensitive.

This proof has been completed.

Theorem 3.3 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is ( F 1 , F 2 ) -sensitive, then h 1 , ∞ is ( F 1 , F 2 ) -sensitive.

Proof. Since h ¯ 1 , ∞ is ( F 1 , F 2 ) -sensitive with the sensitive constant λ > 0 , then for any open set U of κ ( X ) and any ε > 0 , there exist V ∈ B ( U , ε ) such that

{ k ∈ ℤ + : H ( h ¯ 1 k ( U ) , h ¯ 1 k ( V ) ) > λ } ∈ F 2

and

{ k ∈ ℤ + : H ( h ¯ 1 k ( U ) , h ¯ 1 k ( V ) ) < λ } ∈ F 1 .

By the definition, there are two integers m , p ∈ ℕ such that

H ( h ¯ 1 m ( U ) , h ¯ 1 m ( V ) ) > λ and H ( h ¯ 1 p ( U ) , h ¯ 1 p ( V ) ) < λ .

Now, let x ∈ X and ε > 0 be given, then, taking U = { x } ∈ κ ( X ) . We obtain that there exists V ∈ B ( { x } , ε ) such that

H ( h ¯ 1 m ( { x } ) , h ¯ 1 m ( V ) ) = H ( h ¯ 1 m ( x ) , h ¯ 1 m ( V ) ) > λ

and

H ( h ¯ 1 p ( { x } ) , h ¯ 1 p ( V ) ) = H ( h ¯ 1 p ( x ) , h ¯ 1 p ( V ) ) < λ .

And since

H ( h ¯ 1 k ( x ) , h ¯ 1 k ( V ) ) = sup y ∈ V d ( h 1 k ( x ) , h 1 k ( y ) ) ≥ λ

for any k ∈ ℕ . Then, according to the compactness of V and the continuity of h ¯ n ( n ∈ ℤ + ) , there is y 0 ∈ V such that

H ( h ¯ 1 m ( x ) , h ¯ 1 m ( V ) ) = d ( h 1 m ( x ) , h 1 m ( y 0 ) ) > λ

and

H ( h ¯ 1 p ( x ) , h ¯ 1 p ( V ) ) = d ( h 1 p ( x ) , h 1 p ( y 0 ) ) > λ

that is

m ∈ { k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y 0 ) ) > λ }

and

p ∈ { k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y 0 ) ) < λ } .

Since U ∈ B ( { x } , ε ) implies U ⊂ B ( x , ε ) . And consequently, y 0 ∈ B ( x , ε ) . Then

{ k ∈ ℤ + : H ( h ¯ 1 k ( U ) , h ¯ 1 k ( V ) ) > λ } ⊂ { k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y 0 ) ) > λ }

and

{ k ∈ ℤ + : H ( h ¯ 1 k ( U ) , h ¯ 1 k ( V ) ) < λ } ⊂ { k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y 0 ) ) < λ }

Thus, h 1 , ∞ is ( F 1 , F 2 ) -sensitive.

This proof has been completed.

Theorem 3.4 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is F -transitive, then h 1 , ∞ is F -transitive.

Proof. Let U , V be two nonempty open subsets of X, due to Lemma 3.1, e ( U ) and e ( V ) are nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is F -transitive, then N h ¯ 1 , ∞ ( e ( U ) , e ( V ) ) ∈ F . By the definition, let

m ∈ N h ¯ 1 , ∞ ( e ( U ) , e ( V ) ) ∈ F ,

then

h ¯ 1 m ( e ( U ) ) ∩ e ( V ) ≠ ϕ ,

according to Lemma 3.1,

h ¯ 1 m ( e ( U ) ) ∩ e ( V ) = h ¯ 1 m ( e ( U ) ∩ e ( V ) ) ≠ ϕ .

Further, we obtain

h ¯ 1 m ( e ( U ) ) ∩ e ( V ) ⊆ e ( h 1 m ( U ) ) ∩ e ( V ) = e ( h 1 m ( U ) ∩ V ) ≠ ϕ .

Hence,

h 1 m ( U ) ∩ V ≠ ϕ i.e. N h 1 , ∞ ( e ( U ) , e ( V ) ) ∈ F .

Thus, h 1 , ∞ is F -transitive.

This proof has been completed.

Theorem 3.5 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. If h ¯ 1 , ∞ is F -accessible, then h 1 , ∞ is F -accessible.

Proof. Let U , V be two nonempty open subsets of X, due to Lemma 3.1, e ( U ) and e ( V ) are nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is F -accessible, then for any ε > 0 , there exists K 1 ∈ e ( U ) , K 2 ∈ e ( V ) such that

{ k ∈ ℤ + : H ( h ¯ 1 k ( K 1 ) , h ¯ 1 k ( K 2 ) ) < ε } ∈ F ,

by the definition, let

m ∈ { k ∈ ℤ + : H ( h ¯ 1 k ( K 1 ) , h ¯ 1 k ( K 2 ) ) < ε }

one has

H ( h ¯ 1 m ( K 1 ) , h ¯ 1 m ( K 2 ) ) < ε .

Now, for any x ∈ U , let K 1 = { x } ∈ e ( U ) then

H ( h ¯ 1 m ( { x } ) , h ¯ 1 m ( K 2 ) ) = H ( h ¯ 1 m ( x ) , h ¯ 1 m ( K 2 ) ) < ε

that is

H ( h ¯ 1 m ( x ) , h ¯ 1 m ( K 2 ) ) = sup y ∈ K 2 d ( h 1 m ( x ) , h 1 m ( y ) ) < ε

according to the compactness of K 2 and the continuity of h ¯ n ( n ∈ ℤ + ) , there is y 0 ∈ K 2 such that

H ( h ¯ 1 m ( x ) , h ¯ 1 m ( K 2 ) ) = d ( h 1 m ( x ) , h 1 m ( y 0 ) ) < ε ,

one has

m ∈ { k ∈ ℤ + : d ( h 1 m ( x ) , h 1 m ( y 0 ) ) < ε } ,

then

{ k ∈ ℤ + : H ( h ¯ 1 k ( K 1 ) , h ¯ 1 k ( K 2 ) ) < ε } ⊆ { k ∈ ℤ + : d ( h 1 k ( x ) , h 1 k ( y 0 ) ) < ε } ∈ F

and hence

{ k ∈ ℤ + : d ( h 1 m ( x ) , h 1 m ( y 0 ) ) < ε } ∈ F .

Thus, h 1 , ∞ is F -accessible.

This proof has been completed.

Theorem 3.6 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is F -weakly mixing, then h 1 , ∞ is F -weakly mixing.

Proof. Let U i , V i ( i = 1 , 2 ) be two nonempty open subsets of X, due to Lemma 3.1, e ( U i ) , e ( V i ) ( i = 1 , 2 ) are nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is F -weakly mixing, then

{ k ∈ ℤ + : h ¯ 1 k ( e ( U 1 ) ) ∩ e ( V 1 ) ≠ φ and h ¯ 1 k ( e ( U 2 ) ) ∩ e ( V 2 ) ≠ φ } ∈ F

Taking

m ∈ { k ∈ ℤ + : h ¯ 1 k ( e ( U 1 ) ) ∩ e ( V 1 ) ≠ φ and h ¯ 1 k ( e ( U 2 ) ) ∩ e ( V 2 ) ≠ φ } ∈ F

one has

h ¯ 1 m ( e ( U 1 ) ) ∩ e ( V 1 ) ≠ ϕ and h ¯ 1 m ( e ( U 2 ) ) ∩ e ( V 2 ) ≠ ϕ

Due to Lemma 3.1,

h 1 m ¯ ( e ( U 1 ) ) ∩ e ( V 1 ) ≠ ϕ and h 1 m ¯ ( e ( U 2 ) ) ∩ e ( V 2 ) ≠ ϕ .

Further, one has

e ( h 1 m ( U 1 ) ) ∩ e ( V 1 ) = e ( h 1 m ( U 1 ) ∩ V 1 ) ≠ ϕ

and

e ( h 1 m ( U 2 ) ) ∩ e ( V 2 ) = e ( h 1 m ( U 2 ) ∩ V 2 ) ≠ ϕ

by Lemma 3.1,

h 1 m ( U 1 ) ∩ V 1 ≠ ϕ and h 1 m ( U 2 ) ∩ V 2 ≠ ϕ .

That is

m ∈ { k ∈ ℤ + : h 1 k ( U 1 ) ∩ V 1 ≠ φ and h 1 k ( U 2 ) ∩ V 2 ≠ ϕ }

Then

{ k ∈ ℤ + : h ¯ 1 k ( e ( U 1 ) ) ∩ e ( V 1 ) ≠ φ and h ¯ 1 k ( e ( U 2 ) ) ∩ e ( V 2 ) ≠ ϕ } ⊆ { k ∈ ℤ + : h 1 k ( U 1 ) ∩ V 1 ≠ φ and h 1 k ( U 2 ) ∩ V 2 ≠ φ } ∈ F

This proves that h 1 , ∞ is F -weakly mixing.

This proof has been completed.

Theorem 3.7 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is F -m-sensitive, then h 1 , ∞ is F -m-sensitive.

Proof. Let U be a nonempty open subsets of X, then e ( U ) is nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is F -m-sensitive, then there exist a real number λ > 0 and m open sets A 1 , A 2 , ⋯ , A m ; B 1 , B 2 , ⋯ , B m ∈ e ( U ) such that

S h ¯ 1 , ∞ , k ( e ( U ) , λ ) ∈ F .

Taking p ∈ S h ¯ 1 , ∞ , k ( e ( U ) , λ ) , one has

H ( h ¯ 1 p ( A i ) , h ¯ 1 p ( B i ) ) ≥ λ

for any i , j ∈ { 1 , 2 , ⋯ , m } ( i ≠ j ) . That is, p ∈ S h 1 , ∞ , k ( U , λ ) .

Now, let x 1 , x 2 , ⋯ , x m ∈ U , taking

B 1 = { x 1 } , B 2 = { x 2 } , ⋯ , B m = { x m } ∈ e ( U )

Then

H ( h ¯ 1 p { x i } , h ¯ 1 p ( B j ) ) = H ( h ¯ 1 p ( x i ) , h ¯ 1 p ( B j ) ) ≥ λ

for any i , j ∈ { 1 , 2 , ⋯ , m } ( i ≠ j ) . And since

H ( h ¯ 1 p ( x i ) , h ¯ 1 p ( B j ) ) = sup y j ∈ B j d ( h 1 p ( x i ) , h 1 p ( y j ) ) ≥ λ

According to the compactness of B 1 = { x 1 } , B 2 = { x 2 } , ⋯ , B m = { x m } and the continuity of h ¯ n ( n ∈ ℤ + ) , there is y 1 ∈ B 1 , y 2 ∈ B 2 , ⋯ , y m ∈ B m such that

H ( h ¯ 1 p { x i } , h ¯ 1 p ( B j ) ) = d ( h ¯ 1 p ( x i ) , h ¯ 1 p ( y i ) ) ≥ λ ,

for any i , j ∈ { 1 , 2 , ⋯ , m } ( i ≠ j ) .

One has that p ∈ S h 1 , ∞ , k ( U , λ ) ∈ F . This proves that h 1 , ∞ is F -m-sensitive.

This proof has been completed.

Theorem 3.8 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is infinitely sensitive, then h 1 , ∞ is infinitely sensitive.

Proof. Let U be a nonempty open subsets of X, then e ( U ) is nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is infinitely sensitive with the sensitive constant λ > 0 , then there exist K 1 , K 2 ∈ e ( U ) such that

lim sup k → ∞ H ( h ¯ 1 k ( K 1 ) , h ¯ 1 k ( K 2 ) ) ≥ λ

Now, let x ∈ U , taking K 1 = { x } ∈ e ( U ) . Then

lim sup k → ∞ H ( h ¯ 1 k ( { x } ) , h ¯ 1 k ( K 2 ) ) = lim sup k → ∞ H ( h ¯ 1 k ( x ) , h ¯ 1 k ( K 2 ) ) ≥ λ

And since

H ( h ¯ 1 k ( x ) , h ¯ 1 k ( K 2 ) ) = sup y ∈ K 2 d ( h 1 k ( x ) , h 1 k ( y ) ) ≥ λ

According to the compactness of K 2 and the continuity of h ¯ n ( n ∈ ℤ + ) , there exists y 0 ∈ K 2 such that

lim sup k → ∞ H ( h ¯ 1 k ( x ) , h ¯ 1 k ( K 2 ) ) = lim sup k → ∞ d ( h ¯ 1 k ( x ) , h ¯ 1 k ( y 0 ) ) ≥ λ ,

that is for any U ⊂ X , there exist x , y 0 ∈ U such that

lim sup k → ∞ d ( h 1 k ( x ) , h 1 k ( y 0 ) ) ≥ λ

Thus, h 1 , ∞ is infinitely sensitive.

This proof has been completed.

Theorem 3.9 Let ( X , d ) be a compact metric space and h 1 , ∞ be continuous self-mapping sequence on X. h ¯ 1 , ∞ is syndetically transitive, then h 1 , ∞ is syndetically transitive.

Proof. Let U , V be two nonempty open subsets of X, due to Lemma 3.1, e ( U ) and e ( V ) are nonempty open subsets of κ ( X ) . Since h ¯ 1 , ∞ is syndetically transitive, then

N h ¯ 1 , ∞ ( e ( U ) , e ( V ) ) = { n ∈ ℕ : h ¯ 1 n ( e ( U ) ) ∩ e ( V ) ≠ φ }

is syndetic. For any m ∈ N h ¯ 1 , ∞ ( e ( U ) , e ( V ) ) , one has that h ¯ 1 m ( e ( U ) ) ∩ e ( V ) ≠ ϕ . according to Lemma 3.1,

h ¯ 1 m ( e ( U ) ) ∩ e ( V ) = h 1 m ¯ ( e ( U ) ) ∩ e ( V ) ≠ ϕ .

Further, we obtain

h 1 m ¯ ( e ( U ) ) ∩ e ( V ) ⊆ e ( h 1 m ( U ) ) ∩ e ( V ) ≠ ϕ

So, h 1 m ( U ) ∩ V ≠ ϕ , i.e. m ∈ N h 1 , ∞ ( U , V ) .

Thus, N h 1 , ∞ ( U , V ) is syndetic, which proves that h 1 , ∞ is syndetically transitive.

This proof has been completed.

In set-valued discrete dynamical systems, this paper studies the chaoticity in the sense of Furstenberg families. Some sufficient conditions of ( F 1 , F 2 ) -sensitive, F -sensitive, F -transitive, F -accessible, F -weakly mixing, F -m-sensitive, infinitely sensitive, or syndetically transitive are obtained. Based on the conclusions of this paper, there are some further research in set-valued discrete dynamical systems which are worthy of studying. For example, Li-Yorke chaos, Devaney chaos, positive entropy chaos, and others.

The first author Xiaofang Yang, the author Yongxi Jiang have one affiliation, that is, Sichuan University of Science and Engineering. The corresponding author Tianxiu Lu has two affiliations, that is, Sichuan University of Science and Engineering and Key Laboratory of Higher Education of Sichuan Province for Enterprise Informationalization and Internet of Things.

This work was funded by the National Natural Science Foundation of China (No. 11501391), the Opening Project of Key Laboratory of Higher Education of Sichuan Province for Enterprise Informationalization and Internet of Things (No. 2020WZJ01), the Scientific Research Project of Sichuan University of Science and Engineering (No. 2020RC24), and the Graduate student Innovation Fund (Nos. y2020077, cx2020188).

There are many thanks to the experts for their valuable suggestions.

The authors declare no conflicts of interest regarding the publication of this paper.

Yang, X.F., Jiang, Y.X. and Lu, T.X. (2021) Chaotic Properties in the Sense of Furstenberg Families in Set-Valued Discrete Dynamical Systems. Open Journal of Applied Sciences, 11, 343-353. https://doi.org/10.4236/ojapps.2021.113025