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Research Article

On Ergodic and Inverse Shadowing Properties of Set-Valued Mapping

[version 1; peer review: 1 approved, 1 approved with reservations, 1 not approved]
PUBLISHED 20 Feb 2026
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This article is included in the Fallujah Multidisciplinary Science and Innovation gateway.

Abstract

Background

Shadowing-type properties play a fundamental role in the qualitative theory of dynamical systems, as they describe the relationship between approximate trajectories and exact orbits. In recent years, increasing attention has been given to extending these concepts to set-valued mappings, which naturally arise in various areas of mathematics and applied sciences. However, several shadowing-related notions for such mappings remain insufficiently explored.

Methods

In this work, we introduce precise definitions of the inverse shadowing property and the ergodic shadowing property for set-valued mappings. We analyse these properties within a general topological framework and examine their behaviour under the shift mapping on the inverse limit space. The relationships between inverse shadowing and ergodic shadowing are investigated using tools from topological dynamics.

Results

We establish connections between the inverse shadowing property and the ergodic shadowing property for set-valued mappings. In particular, we show how these properties interact when considered together with the shift mapping on the inverse limit space, and we identify conditions under which one property implies the other.

Conclusions

The results provide a clearer understanding of shadowing phenomena for set-valued mappings and highlight the role of inverse limit spaces in studying their dynamical behavior. This work contributes to the development of shadowing theory beyond single-valued dynamics and offers a foundation for further investigations in this direction.

Keywords

set–valued mappings; shift mapping σ_H; inverse shadowing property.

1. Introduction

The phenomenon of shadowing approximation trajectories (pseudo trajectories) of dynamical systems by exact trajectories is one of the most extensively examined issues in contemporary global dynamical systems theory (for example,1,2). On the other hand, there has begun an equally intense development at the inverse shadowing problem, where a class of methods generating pseudo trajectories is specified and the question is studied as to if it is possible to approximate any precise trajectory by a trajectory of any method from this class (see3,4).

Román-Flores,5 in 2003, researched the relationship of transitivity with the associated system. After his research, numerous scientists examined the characteristics of set-valued discrete systems. For instance, the transitivity and mixing.6,7 The ergodic shadowing property is shown by Shabani and Ahmadi8 to be a feature of chain mixing in non-autonomous discrete-time dynamical systems.

Koo and Lee,9 in 2024 proved that the uniform ergodic shadowing characteristic holds for sequences of homeomorphisms on non-compact metric spaces. Al-Sharaa and Russl A.,10 in 2023, study generic non-autonomous discrete dynamical systems’ shadowing and w-expansive properties and the relationship between them. In the recent work,11 in 2025, Koo and Lee introduced the notions of dynamical systems on non-compact metric spaces and their ergodic shadowing property.

In this research, we focus on the inverse shadowing property with the ergodic shadowing property in set-valued systems and its relation with inverse limits. We introduce a new definition of the inverse and ergodic shadowing properties of set-valued mappings. This means we will create a space whose elements are sets. We will structure examples that satisfy the new definition in the future research. In the following section, we introduce some important concepts that we need:

1.1 Non–autonomous discrete system

Let be represented by any compact metric space, where d is the symbol for the metric on . Let Hη: , η be a series of mappings represented by H1,=(H1,H2,) . The above sequence indicates a non–autonomous discrete system (,H1,) . According to this mapping sequence. The point S ’s trajectory can be defined as orb(S,H1,)=(H1η(S)),η, where H1η=HηH1 , and H10 represents the identity mapping similarly Hηk=Hη+k1Hη+1Hη .

K() is the hyperspace of . The space of compact nonempty subsets of where the Hausdorff metric dH is defined as follows: dH(Α,Β)=max{supSΑinfTΒd(S,T),supTΒinfSΑd(S,T)} for any Α,ΒK() . (K(),dH) is a compact metric space and H:K()K() is a set–valued mapping on . We call the pair (,H) a set–valued system.

The product topology is applied to Ζ , which is the compact metric space of all bi–infinite sequences ={Sk:k} in . Let H:K()K() be a set–valued mapping for a constant value δ>0 , where ΦH(δ) represents the set of all δ pseudo trajectories of H . We will provide definitions of inverse shadowing property and ergodic shadowing property for set–valued mapping.

A mapping :ΦH(δ)Ζ that satisfies 0(S)=S,S is known as a δ method for H . For any positive ε , there is a positive δ such that for every S in , and any δ method :Ζ , there exists T in , such that d(Hk(S),k(T)<ε) for any k in , we say that H has inverse shadowing property, denoted as ISP.

Considering a sequence ={S¡}¡ , take

D(,H,δ)={¡:d(H(S¡),S¡+1)δ}Dη(,H,δ)=D(,H,δ){η,,2,1,0,1,2,,η}

In consideration of a sequence ={S¡}¡ and a point S put

DS(,S,H,δ)={¡:d(H¡(S),S¡)δ},DSη(,S,H,δ)=DS(,S,H,δ){η,,2,1,0,1,2,,η}.

Let ={S¡}¡ be defined as an δ ergodic pseudo trajectories for H if the following limit holds:

lim|η|(card(Dη(,H,δ))/η)=0.

An δ ergodic pseudo trajectory is considered ϵ ergodic shadowing with a point S denoted by ESP if lim|η|(card(DSη(,S,H,δ))/η)=0 .

We propose that an H inveriant set Λ possesses an ergodic shadowing property when, for every ϵ>0 , there exists a δ>0 that means all δ ergodic pseudo trajectories in Λ can be ergodic shadowed by a single point S .

A closed subspace H={(Sη):S,H(Sη)=Sη+1,η} of Ζ in addition to the corresponding shift mapping σH:HH , which is defined as σH((Sη))=(Tη) where Tη=Sη+1 for all η is referred to as the inverse limit space of H . It is important to observe that the compact metric space H is determined by the metric d , which is defined as d((S¡),(T¡))=¡(d(S¡,T¡)/2|¡|) .

For each ¡,j , consider ¡ the projection mapping π¡:HK() by π¡(S)=S¡ for any SH where S={,S¡1,S¡,S¡+1,} , for any ¡ , the mapping πi satisfies that Hπ¡=π¡σH as it is an open continuous mapping.

2. Results

Theorem 2.1.

A continuous surjective set–valued mapping on a compact metric space is denoted by H:K()K() . Assuming H has ESP, the corresponding shift mapping σH on the inverse limit space H also has ESP.

Proof:

Let ϵ be greater than zero; then diam()=α we can select N from such that (α2N1)<(ϵ8) . Since d(S,T)<γ , the uniform continuity of H ensures that d(H¡(S),H¡(T))<(ϵ8) for 0¡2N . Given that H has ESP. Any τ ergodic pseudo trajectory is γ ergodic shadowed by a point in for any γ>0 there is τ>0 . Get δ>0 so that 0<δ2N<τ .

Suppose {Sη}ηH be a δ ergodic pseudo trajectory with σH . Because {η\d(H(SNη),SNη+1)τ}{η\d(σH(Sη),Sη+1)δ} the sequence of {SNη} forms a τ ergodic pseudo trajectory for H . However, there exists T that means lim|m|(card({η\d(Hη(T),SNη)γ}{m+1,,m1}))×m1=0 .

Suppose T¡N=H¡(T) for any ¡0 and T¡NH1(T¡+1N) for ¡<0 , the T=(T¡)H . If η{η/d(Hη(T),Sη)γ} then η{η/d(ση(T),Sη)ϵ} which is to say {η/d(ση(T),Sη)ϵ}{η/d(Hη(T),SNη)γ} . Consequently, {Sη}H could display ϵ ergodic shadowed for TH . ■

Theorem 2.2.

A continuous surjective set–valued mapping on a compact metric space is denoted by H:K()K() . Assuming H has ISP, the corresponding shift mapping σH on the inverse limit space H also has ISP.

Proof:

Let ϵ be greater than zero; then diam()=α we can select N from so that (α2N1)<(ϵ8) . Since d(S,T)<γ , the uniform continuity of H ensures that d(H¡(S),H¡(T))<(ϵ8) for 0¡2N .

Given that H has ISP, for each γ>0 ,there is τ>0 which means that with each S and every τ method , it exists T satisfying d(Hk(S),k(T))<γ , for all k .

Select δ>0 such that 0<δ2N<τ . suppose that :H Φσ is a δ method for σH . We construct a τ method of H this way: let S , choose a point S=(S¡)H where πN(S)=S . If constitutes a δ method of σH , therefore, SH , d(σH(η(S)),η+1(S))<δ .

Let :Ζ be defined as (S)={η(S)}η , where η(S)=πN(η(S)) . It is evident that (S) forms a τ pseudo trajectory for H ; hence, behaves as a τ method for H . Since H is ISP, every πN(S) , where SH it has T that gives d(Hη(πN(S)),η(T))<γ . If TH where πN(T)=T ; then d(σHη(S),η(T))<ϵ ; this means that σH has ISP. ■

Theorem 2.3.

A local homeomorphism set–valued mapping on a compact metric space is denoted by H:K()K() . Assuming the shift mapping σH on H has ESP, then H also has ESP.

Proof:

For each ϵ>0 , according to the ESP of σH , it has a τ>0 for every τ ergodic pseudo trajectory in σH a point in H that forms ϵ ergodic shadowed. Let α=diam() , and choose N so that (α2N1)<(τ4) .

H be the local homeomorphism; it has a γ such that 0<γ<(τ/4) and H|U:UU forms a homeomorphism when U defines the γ neighborhood of S . H being uniformly continuous, for τ/8 , there is 0<Γ<(τ/8) where d(S,T)<Γ means d(Hj(S),Hj(T))<(τ/8) for every j,|j|N .

Let {Sη}η be a Γ ergodic pseudo trajectory for H ; define S0η=Sη and Sη=(S¡η)H . If η{η|d(H(Sη),Sη+1)Γ} , then η{η|d(σH(Sη),Sη+1)τ} . This shows that {η|d(σH(Sη),Sη+1)τ}{η|d(H(Sη),Sη+1)Γ} , and hence {Sη} defines a τ ergodic pseudo trajectory for σH . Since σH has ESP, there is T=(Ti) in H such that lim|m|({η|d(σHη(T),Sη)ϵ}{m+1,,m1}/m)=0 .

If η{η|d(σHη(T),Sη)ϵ} , then η{η|d(Hη(T0),S0η)ϵ} , and we get {η|d(Hη(T0),Sη)ϵ},{η|d(σHη(T),Sη)ϵ} . It is now evident by definition that H has ESP.■

Theorem 2.4.

A local homeomorphism set–valued mapping on a compact metric space is denoted by H:K()K() . Assuming the shift mapping σH on H has ISP, then H also has ISP.

Proof:

For each ϵ>0 by ISP of σH , there is τ>0 such that, for each of SH and for every τ method of σH , there is TH so that d(σHη(S),η(T))<ϵ .

Let α=diam() , select N so that (α2N1)<(τ4) . H be a local homeomorphism; U represents the γ neighborhood of S , and H|U:UU is a homeomorphism if there is a γ such that 0<γ<(τ/4) . Since H represents uniform continuity at τ/8 ; for every j where |j|N there exists 0<Γ<(τ/8) such that d(S,T)<Γ and d(Hj(S),Hj(T))<(τ/8) .

Let S be an element of , and define :ΦH(δ) as a γ method of H . Let :H H so that (S)={η(S)}η with π0((S))=η(S) we have d(σH(η(S)),η+1(S))<δ . Therefore :H H represents a δ method for σH , since σH has the ISP; thus, given SH there is TH , which means d(σHη(S),η(T))<ϵ , this implies that d(Hη(S),η(T))<ϵ ; hence, H has the ISP. ■

3. Conclusion

In this paper, we present a new definition of the inverse and ergodic shadowing properties for set-valued mappings. We explore the relationship between the inverse shadowing property and the ergodic shadowing property of set-valued mappings, as well as their connection to the shift mapping σH on the inverse limit space.

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Wattan Kamil F and AL-Shara'a IMT. On Ergodic and Inverse Shadowing Properties of Set-Valued Mapping [version 1; peer review: 1 approved, 1 approved with reservations, 1 not approved]. F1000Research 2026, 15:299 (https://doi.org/10.12688/f1000research.173380.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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ApprovedThe paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions
Version 1
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PUBLISHED 20 Feb 2026
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Reviewer Report 13 Mar 2026
Syahida Che Dzul-Kifli, Universiti Kebangsaan Malaysia, Bangi, Malaysia 
Approved with Reservations
VIEWS 14
1) The abstract should clearly indicate the principal results obtained regarding the relationship between the inverse shadowing property and the ergodic shadowing property for set-valued mappings.
2) In the Introduction section, several sentences lack clarity and the logical flow between ... Continue reading
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CITE
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Dzul-Kifli SC. Reviewer Report For: On Ergodic and Inverse Shadowing Properties of Set-Valued Mapping [version 1; peer review: 1 approved, 1 approved with reservations, 1 not approved]. F1000Research 2026, 15:299 (https://doi.org/10.5256/f1000research.191190.r461381)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the constructive and helpful comments.
    • The abstract and introduction have been improved to clearly reflect the main contributions.
    • The structure of the
    ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the constructive and helpful comments.
    • The abstract and introduction have been improved to clearly reflect the main contributions.
    • The structure of the
    ... Continue reading
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13
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Reviewer Report 12 Mar 2026
Abdul Gaffar Khan, University of Delhi, Delhi, New Delhi, India 
Not Approved
VIEWS 13
The results seem to be publishable at first glance, but the quality of the writing and structure needs to be improved a lot. Authors are highly recommended to do the careful reading and address the comments below. Note that these ... Continue reading
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Khan AG. Reviewer Report For: On Ergodic and Inverse Shadowing Properties of Set-Valued Mapping [version 1; peer review: 1 approved, 1 approved with reservations, 1 not approved]. F1000Research 2026, 15:299 (https://doi.org/10.5256/f1000research.191190.r461379)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the careful evaluation and valuable remarks.
    • The notation has been standardized throughout the manuscript to improve consistency and readability.
    • The definition of
    ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the careful evaluation and valuable remarks.
    • The notation has been standardized throughout the manuscript to improve consistency and readability.
    • The definition of
    ... Continue reading
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12
Cite
Reviewer Report 09 Mar 2026
Khundrakpam Binod Mangang, Manipur University, Imphal, Manipur, India 
Approved
VIEWS 12
This paper explores the intersection of set-valued dynamical systems and shadowing theory, focusing on the Ergodic Shadowing Property (ESP) and the Inverse Shadowing Property (ISP).
Recommendation: Accept / Highly Favourable
1. Theoretical Significance
The research successfully ... Continue reading
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CITE
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Mangang KB. Reviewer Report For: On Ergodic and Inverse Shadowing Properties of Set-Valued Mapping [version 1; peer review: 1 approved, 1 approved with reservations, 1 not approved]. F1000Research 2026, 15:299 (https://doi.org/10.5256/f1000research.191190.r461372)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the detailed and insightful comments.
    • The abstract has been revised to clearly state the main results and highlight the relationship between inverse shadowing
    ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 16 Apr 2026
    farah wattan, University of Babylon, Iraq
    16 Apr 2026
    Author Response
    We thank the reviewer for the detailed and insightful comments.
    • The abstract has been revised to clearly state the main results and highlight the relationship between inverse shadowing
    ... Continue reading

Comments on this article Comments (0)

Version 2
VERSION 2 PUBLISHED 20 Feb 2026
Comment
Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions
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