Processing math: 100%
Research article

On multivalued maps for φ-contractions involving orbits with application

  • In [14], Proinov established the existence of fixed point theorems regarding as a generalization of the Banach contraction principle (BCP) of self mapping under an influence of gauge function (GF). In this paper, we develop some existence results on φ-contraction for multivalued maps via b-Bianchini-Grandolfi gauge function (B-GGF) in class of b-metric spaces and consequently assure the existence results in the module of simulation function as well α-admissible mapping. An extensive set of nontrivial example is given to justify our claim. At the end, we give an application to prove the existence behavior for the system of integral inclusion.

    Citation: Amjad Ali, Muhammad Arshad, Awais Asif, Ekrem Savas, Choonkil Park, Dong Yun Shin. On multivalued maps for φ-contractions involving orbits with application[J]. AIMS Mathematics, 2021, 6(7): 7532-7554. doi: 10.3934/math.2021440

    Related Papers:

    [1] Moirangthem Pradeep Singh, Yumnam Rohen, Khairul Habib Alam, Junaid Ahmad, Walid Emam . On fixed point and an application of $ C^* $-algebra valued $ (\alpha, \beta) $-Bianchini-Grandolfi gauge contractions. AIMS Mathematics, 2024, 9(6): 15172-15189. doi: 10.3934/math.2024736
    [2] Monairah Alansari, Mohammed Shehu Shagari, Akbar Azam, Nawab Hussain . Admissible multivalued hybrid $\mathcal{Z}$-contractions with applications. AIMS Mathematics, 2021, 6(1): 420-441. doi: 10.3934/math.2021026
    [3] Afrah Ahmad Noman Abdou . Chatterjea type theorems for complex valued extended $ b $-metric spaces with applications. AIMS Mathematics, 2023, 8(8): 19142-19160. doi: 10.3934/math.2023977
    [4] Tahair Rasham, Najma Noor, Muhammad Safeer, Ravi Prakash Agarwal, Hassen Aydi, Manuel De La Sen . On dominated multivalued operators involving nonlinear contractions and applications. AIMS Mathematics, 2024, 9(1): 1-21. doi: 10.3934/math.2024001
    [5] Yan Han, Shaoyuan Xu, Jin Chen, Huijuan Yang . Fixed point theorems for $ b $-generalized contractive mappings with weak continuity conditions. AIMS Mathematics, 2024, 9(6): 15024-15039. doi: 10.3934/math.2024728
    [6] Samina Batul, Faisar Mehmood, Azhar Hussain, Dur-e-Shehwar Sagheer, Hassen Aydi, Aiman Mukheimer . Multivalued contraction maps on fuzzy $ b $-metric spaces and an application. AIMS Mathematics, 2022, 7(4): 5925-5942. doi: 10.3934/math.2022330
    [7] Rashid Ali, Faisar Mehmood, Aqib Saghir, Hassen Aydi, Saber Mansour, Wajdi Kallel . Solution of integral equations for multivalued maps in fuzzy $ b $-metric spaces using Geraghty type contractions. AIMS Mathematics, 2023, 8(7): 16633-16654. doi: 10.3934/math.2023851
    [8] Hongyan Guan, Jinze Gou, Yan Hao . On some weak contractive mappings of integral type and fixed point results in $ b $-metric spaces. AIMS Mathematics, 2024, 9(2): 4729-4748. doi: 10.3934/math.2024228
    [9] Jamshaid Ahmad, Abdullah Eqal Al-Mazrooei, Hassen Aydi, Manuel De La Sen . Rational contractions on complex-valued extended $ b $-metric spaces and an application. AIMS Mathematics, 2023, 8(2): 3338-3352. doi: 10.3934/math.2023172
    [10] Pragati Gautam, Vishnu Narayan Mishra, Rifaqat Ali, Swapnil Verma . Interpolative Chatterjea and cyclic Chatterjea contraction on quasi-partial $b$-metric space. AIMS Mathematics, 2021, 6(2): 1727-1742. doi: 10.3934/math.2021103
  • In [14], Proinov established the existence of fixed point theorems regarding as a generalization of the Banach contraction principle (BCP) of self mapping under an influence of gauge function (GF). In this paper, we develop some existence results on φ-contraction for multivalued maps via b-Bianchini-Grandolfi gauge function (B-GGF) in class of b-metric spaces and consequently assure the existence results in the module of simulation function as well α-admissible mapping. An extensive set of nontrivial example is given to justify our claim. At the end, we give an application to prove the existence behavior for the system of integral inclusion.



    Let (ˆU,d) be a metric space. For ˆˆU and β1ˆU, let db(ˆ1,β1)=inf{db(ˆ1,ˆ2):ˆ2β1}. Denote N(ˆU), CL(ˆU), CB(ˆU) by the class all nonempty subsets of ˆU, the class of all nonempty closed subsets of ˆU and the class of all nonempty closed and bounded subsets of ˆU respectively. Define the Hausdorff-Pompeiu metric ˆHb induced by db on CB(ˆU) as follows:

    ˆHb(β1,β2)=max{supˆ1β1db(ˆ1,β2),supˆ2β2db(ˆ2,β1)}

    for all β1,β2CL(ˆU). A point ˆˆU is said to be a fixed point of ˜T:ˆUCL(ˆU), if ˆ˜Tˆ. If, for ˆ0ˆU, there exists a sequence {ˆi} in ˆU such that ˆi˜Tˆi1, then O(˜T,ˆ0)={ˆ0,ˆ1,ˆ2,...} is said to be an orbit of ˜T:ˆUCL(ˆU). A mapping f:ˆUR is said to be ˜T-orbitally lower semi-continuous (o.l.s.c) if {ˆi} is a sequence in O(˜T,ˆ0) and ˆiϱ implies f(ϱ)lim infif(ˆi).

    From now on, Nadler [13] realized the following multivalued version of BCP:

    Theorem 1.1. [13] Let (ˆU,db) be a complete metric space and T:ˆUCB(ˆU) be a Nadler contraction, i.e., there is γ[0,1) such that

    ˆHb(Tˆ1,Tˆ2)γdb(ˆ1,ˆ2)forallˆ1,ˆ2ˆU.

    Then T possesses at least one fixed point.

    We start the following results for main sequel.

    Lemma 1.2. [13] Let (ˆU,db) be a metric space, β2CB(ˆU) and ˆˆU. Then, for each ϵ>0, there exists νβ2 such that

    db(ˆ,ν)db(ˆ,β2)+ϵ.

    Lemma 1.3. [19] Let (ˆU,db) be a metric space and β1, β2CB(ˆU) with ˆHb(β1,β2)>0. Then for all h>1 and ˆβ1, there exists ν=ν(ˆ)β2 such that

    db(ˆ,ν)<hˆHb(β1,β2).

    There after, many researchers worked on existence of fixed point theorems of single valued mappings can improve in the module of multi-valued mappings that satisfying various classes of contractive mappings (see [1,2,3,4,6,9,10,12,15,17,18,19,20]).

    Definition 1.4. [8] A b-metric space on a nonempty set M is a function b:ˆU׈UR+ such that for all ˆ1,ˆ2,ˆ3ˆU and a given real number s1, the following conditions hold:

    (bi) db(ˆ1,ˆ2)=0 if and only if ˆ1=ˆ2;

    (bii) db(ˆ1,ˆ2)=db(ˆ2,ˆ1);

    (biii) db(ˆ1,ˆ3)s[db(ˆ1,ˆ2)+db(ˆ2,ˆ3)].

    The pair (ˆU,db) is known as b-metric space.

    The following examples present the context of b-metric spaces, which are essentially larger than the context of metric spaces [8].

    Example 1.5. [8] Let ˆU=lp(R) with p(0,1) where lp(R)={{ˆi}R:+i=1|ˆi|p<}. A function b:ˆU׈UR+ is given by b(ˆ1,ˆ2)=(+i=1|ˆi|p)1p, where ˆ1=ˆi and ˆ2=ˆi. Then the pair (ˆU,db) is known as b-metric space with s=21p.

    Example 1.6. [8] Let ˆU=Lp[0,1] be the space of all real valued functions ˆ(r), 0r1 in such a way that 10|ˆ(r)|1pdr<. A function b:ˆU׈UR+ is given by b(ˆ1,ˆ2)=(10|ˆ1(r)ˆ2(r)|p)1p. Then the pair (ˆU,db) is known as b-metric space with s=21p.

    Definition 1.7. [8] A sequence {ˆi} in b-metric space ˆU is said to be convergent if there is ˆˆU such that db(ˆi,ˆ)0 as i+ and write limi+(ˆi)=ˆ. A sequence {ˆi} in (ˆU,db) is said to be Cauchy if db(ˆi,ˆi)0 as i,i+. A b-metric space (ˆU,db) is said to be complete if every Cauchy sequence in ˆU converges.

    Note that, in general, the b-metric is not a continuous functional. Recently, Liu et al. [12] produced the following classical function:

    Definition 1.8. Let φ:(0,+)(0,+) satisfy the following conditions:

    (φa) φ is nondecreasing;

    (φb) for all {ˆi} in (0,+), limi+φ(ˆi)=0 if and only if limi+(ˆi)=0;

    (φc) φ is continuous.

    From now on, we denote by φ the set of all function that satisfying (φa)(φc). The following well known two lammas of φ functions will be needed in our forthcoming sequel:

    Lemma 1.9. [12] Let {ˆi}i be a bounded sequence of real numbers and all its convergent subsequences have the same limit γ. Then {ˆi}i is convergent and limi+(ˆi)=γ.

    Lemma 1.10. Let φ:(0,+)(0,+) be a nondecreasing and continuous function with infˆ(0,+)φ(ˆ)=0 and {ˆi}i(0,+). Then

    limi+φ(ˆi)=0ifandonlyiflimi+(ˆi)=0.

    Proof. () Suppose limi+φ(ˆi)=0. Then we claim that the sequence {ˆi} is bounded. In fact, if the sequence is unbounded, then we may assume that ˆi+ and so for all δ>0, there is i0N such that ˆi >δ for all i>i0. Hence φ(δ)φ(ˆi) and so φ(δ)limi+φ(ˆi)=0, which contradicts to φ(δ)>0. Thus {ˆi} is bounded. Hence there exists a subsequence {ˆii}{ˆi} such that limi+{ˆii}=k (where k is nonnegative number). Clearly k0. If k>0, then there is i0N such that {ˆii}(k2,3k2) for all ii0. By (φa), we deduce that φ(k2)limi+{ˆii}=0, which contradicts to φ(k2)>0. Consequently, setting k=0 and by the above lemma, we have limi+(ˆi)=0.

    () Suppose that infˆ(0,+)φ(ˆ)=0. If ˆi0, then for any given ϵ>0, there is k>0 such that φ(k)(0,ϵ) and there exists i1N such that ˆi<k for all i>i1. Therefore, 0<φ(ˆi)φ(k)<ϵ for i>i1. Hence φ(ˆi)0 as i+.

    Throughout this paper E denotes an interval on R+ containing 0, that is, an interval of the form [0,R], [0,R), or [0,+). Proinov [14] introduced the following:

    Lemma 1.11. [14] Let ˆ0Λ (Λ is a closed subset of ˆU) such that

    db(ˆ0,˜Tˆ0)E,

    and ˆiΛ for some i0. Then we have db(ˆi,˜Tˆi)E.

    Definition 1.12. [14] Suppose ˆ0Λ and db(ˆ0,˜Tˆ0)E. Then for an iterate ˆi (i0) which belongs to Λ, we define the closed ball ¯b(ˆi,ρ) with center ˆi and radius ρ>0.

    Lemma 1.13. [14] If an element ˆ0Λ satisfies db(ˆ0,˜Tˆ0)E and ¯b(ˆi,ρ)Λ for some i0, then ˆi+1Λ and ¯b(ˆi+1,ρ)¯b(ˆi,ρ).

    Definition 1.14. [14] Let i1. A function ξ:EE is said to be a gauge function of order i on E if it satisfies the following conditions: (a) ξ(λˆ)<λiξ(ˆ) for all λ(0,1) and ˆE; (b) ξ(ˆ)<ˆ for all ˆE{0}.

    It is easy to see that the first condition of Definition 1.14 is equivalent to the following: ξ(0)=0 and ξ(ˆ)/ˆi is nondecreasing on E{0}.

    Definition 1.15. [14] A gauge function ξ:EE is said to be a B-GGF on E if

    σ(ˆ)=+i=0ξi(ˆ)<,forallˆE.

    Note that a B-GGF also satisfies the following functional equation:

    σ(ˆ)=σ(ξ(ˆ))+ˆ.

    Proinov [14] proved his main results by assuming B-GGF ξ and the mapping T:ΛX satisfying the contractive condition d(T(x)T2(x))ξ(d(x;Tx)) when the underlying space is endowed with a metric. But from now on, in the context of b-metric space for some technical dialectics, Samreen et al. [16] introduced the following class of GF.

    Definition 1.16. [16] A nondecreasing function ξ:EE is said to be a b-B-GGF on E if

    σ(ˆ)=+i=0siξi(ˆ)<,forallˆE

    where s is the coefficient of b-metric space. Moreover, note that a b -B-GGF also satisfies the following functional equation:

    σ(ˆ)=sσ(ξ(ˆ))+ˆ.

    Remark 1.17. Every b-B-GGF is also a B-GGF [7] but the converse may not hold. Furthermore, in [16], Samreen et al. introduced gauge functions in a b -metric space of the form

    ξ(ˆ)={sξ(ˆ)ˆ,ifˆE{0}0,ifˆ=0

    where s is the coefficient of b-metric space. For instance, we refer the following simple examples of gauge functions of order i as:

    (a) ξ(ˆ)=λˆs for all λ(0,1) is a gauge function of order 1 on ˆE;

    (b) ξ(ˆ)=λˆks (λ>0, k>0) is a gauge function of order k on E=[0,l) where l=(1λ)11k.

    In 2015, Khojasteh et al. [11] introduced the concept of simulation function as follows:

    Definition 1.18. [11] A function Γ:R+×R+R is called an SF if

    (Γ1) Γ(0,0)=0;

    (Γ2) Γ(ˆ1,ˆ2)<ˆ2ˆ1 for all ˆ1,ˆ2>0;

    (Γ3) if {ˆ1i}, {ˆ2i}(0,+) such that limi+ˆ1i=limi+ˆ2i>0, then

    lim supi+Γ(ˆ1i,ˆ2i)<0.

    Due to (Γ2), we have Γ(ˆ1,ˆ1)<0 for all ˆ1>0. From now on, we denote by the set of all functions satisfying (Γ1)-(Γ3). Some well known examples of Γ functions presented in the existing exposition are as follows:

    Example 1.19. [11] For i=1,2, let ϑi:R+R+ be continuous functions with ϑi(ˆ1)=0 if and only if ˆ1=0. The following functions Γj:R+×R+R (j=1,,6) are in :

    (a) Γ1(ˆ1,ˆ2)= ϑ1(ˆ2)ϑ2(ˆ1) for all ˆ1,ˆ20, where ϑ1(ˆ1)ˆ1ϑ2(ˆ1) for all ˆ1>0;

    (b) Γ6(ˆ1,ˆ2)=ˆ2ˆ10ς(u)dufor allˆ1,ˆ20, where ς:R+R+ is a function such that

    ϵ0ς(u)duexistsandϵ0ς(u)du>ϵϵ>0.

    Let (ˆU,db) be a metric space, ˜T be a self mapping on ˆU and Γ. ˜T is said to be a -contraction with respect to Γ, if

    Γ(db(˜Tˆ1,˜Tˆ2),db(ˆ1,ˆ2))0,forallˆ1,ˆ2ˆU.

    Due to (Γ2), we have db(Tˆ1,Tˆ2)db(ˆ1,ˆ2) for all distinct points ˆ1,ˆ2ˆU. Thus T is not an isometry, whenever T is a -contraction with respect to Γ. Conversely, if a -contraction mapping T on a metric space possesses a fixed point, then it is necessarily unique.

    In the recent year, Ali et al. [5] initiated the following definition which is a modification of the notion of α-admissible.

    Definition 1.20. [5] Let (ˆU,db) be a metric space and Λ be a nonempty subset of ˆU. A mapping ˜T:ΛCB(ˆU) is called α-admissible if there exists a function α:Λ×Λ[0,+) such that

    α(a,b)1α(ˆ,ν)1,

    for all ˆ˜TaΛ and ν˜TbΛ.

    In this manuscript, we prove the notion of multi-valued Suzuki (SU) type fixed point results via φξ-contraction mapping and (αξ)-contraction mapping in the module of b -metric spaces, where ξ is a b-B-GGF on an interval E with some tangible examples and certain important corollaries are adopted subsequently. Our newly proved results over recent ones chiefly due to Proinov [14] and Ali et al. [1]. As the end results of a succession, we promote our main results to prove the existence of solution for the system of integral inclusion.

    In this section, motivated by the notion of multivalued Suzuki type φ -contraction, we define the notion of multivalued Suzuki type φξ-contraction as follows:

    Definition 2.1. Let (ˆU,db) be a b-metric space with s1, Λ be a closed subset of ˆU and ξ be a b-B-GGF on an interval E. A mapping ˜T:ΛCB(ˆU) is said to be a multivalued SU-type φ-contraction if there exists φφ such that for ˜TˆΛ

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    φ[ˆHb(˜TˆΛ,˜TνΛ)]φ[ξ(Ω(ˆ,ν))], (2.1)

    where

    Ω(ˆ,ν)=max{db(ˆ,ν),db(ˆ,˜Tˆ),db(ν,˜Tν),db(ˆ,˜Tν)+db(ν,˜Tˆ)2s}

    for all ˆΛ, ν˜TˆΛ with db(ˆ,ν)E, and ˆHb(˜TˆΛ,˜TνΛ)>0.

    Clearly in a class b-metric space, if an element ˆ0Λ such that O(ˆ0)Λ satisfies db(ˆ0,˜Tˆ0)E and ¯b(ˆi,ρi)Λ for some i0, then ˆi+1Λ and ¯b(ˆi+1,ρi+1)¯b(ˆi,ρi).

    Our first main result is as follows:

    Theorem 2.2. Let (ˆU,db) be a complete b-metric space with s1, Λ be a closed subset of ˆU and ˜T:ΛCB(ˆU) be a multivalued SU-type φ -contraction. Assume ˆ0Λ such that db(ˆ0,c)E for some c˜Tˆ0Λ. Then there exist an orbit {ˆi} of ˜T in Λ and σΛ such that limi+ˆi=σ. Moreover, σ is a fixed point of ˜T if and only if the function g(ˆ):=db(ˆ,˜TˆΛ) is ˜T-o.l.s.c at σ.

    Proof. Choose ˆ1=c˜Tˆ0Λ. In the presence of this manner db(ˆ0,ˆ1)=0, ˆ0 is a fixed point of ˜T. Thus we assume that db(ˆ0,ˆ1)0. On the other hand, we have

    12smin{db(ˆ0,˜Tˆ0Λ),db(ˆ1,˜Tˆ1Λ)}<db(ˆ0,ˆ1). (2.2)

    Define ρ=σ(db(ˆ0,ˆ1)). From (1.16), we have σ(r)r. Hence db(ˆ0,ˆ1)ρ and so ˆ1¯b(ˆ0,ρ). Since db(ˆ0,ˆ1)E, from (2.1) and (2.2) it follows that

    φ[Hb(˜Tˆ0Λ,˜Tˆ1Λ)]φ[ξ(Ω(ˆ0,ˆ1))]<φ[Ω(ˆ0,ˆ1)].

    By the property of right continuity of φ, there exists a real number h1>1 such that

    φ[h1Hb(˜Tˆ0Λ,˜Tˆ1Λ)]φ[ξ(Ω(ˆ0,ˆ1))]. (2.3)

    From

    db(ˆ1,˜Tˆ1Λ)Hb(˜Tˆ0Λ,˜Tˆ1Λ)<h1Hb(˜Tˆ0Λ,˜Tˆ1Λ),

    by Lemma 1.3, there exists ˆ2˜Tˆ1Λ such that db(ˆ1,ˆ2)h1Hb(˜Tˆ0Λ,˜Tˆ1Λ). Since φ is nondecreasing, by (2.3), this inequality gives that

    φ[(db(ˆ1,ˆ2)]φ[h1Hb(˜Tˆ0Λ,˜Tˆ1Λ)]<φ[Ω(ˆ0,ˆ1))],

    where

    Ω(ˆ0,ˆ1)=max{db(ˆ0,ˆ1),db(ˆ0,˜Tˆ0),db(ˆ1,˜Tˆ1),db(ˆ0,˜Tˆ1)+db(ˆ1,˜Tˆ0)2s}max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1),db(ˆ0,˜Tˆ1)2s}max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1)}.

    Now, we claim that

    φ[(db(ˆ1,ˆ2)]φ[h1Hb(˜Tˆ0Λ,˜Tˆ1Λ)]<φ[db(ˆ0,ˆ1))]. (2.4)

    Let Δ=max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1)}. Assume that Δ=db(ˆ1,˜Tˆ1). Since ˆ2˜Tˆ1Λ, we have

    φ[(db(ˆ1,ˆ2)]φ[h1Hb(˜Tˆ0Λ,˜Tˆ1Λ)]<φ[db(ˆ1,ˆ2))],

    which is a contradiction. Hence (2.4) holds true. We assume that db(ˆ1,ˆ2)0, otherwise, ˆ1 is a fixed point of ˜T. From (φa), (2.4) implies that

    db(ˆ1,ˆ2)<db(ˆ0,ˆ1).

    and so db(ˆ1,ˆ2)E. Next, ˆ2¯b(ˆ0,ρ) since

    db(ˆ0,ˆ2)sdb(ˆ0,ˆ1)+sdb(ˆ1,ˆ2)sdb(ˆ0,ˆ1)+s2db(ˆ1,ˆ2)sdb(ˆ0,ˆ1)+s2ξ(db(ˆ0,ˆ1))=s[db(ˆ0,ˆ1)+sξ(db(ˆ0,ˆ1))]sσdb(ˆ0,ˆ1)db(ˆ0,ˆ1)+sσ(db(ˆ0,ˆ1))=σ(db(ˆ0,ˆ1))=ρ.

    Since

    12smin{db(ˆ1,˜Tˆ1Λ),db(ˆ2,˜Tˆ2Λ)}<db(ˆ1,ˆ2),

    from (2.1), we have

    φ[Hb(˜Tˆ1Λ,˜Tˆ2Λ)]φ[ξ(db(ˆ1,ˆ2)))]<φ[Ω(ˆ1,ˆ2))].

    Since φ is right continuous, there exists a real number h2>1 such that

    φ[h2Hb(˜Tˆ1Λ,˜Tˆ2Λ]φ[ξ(Ω(ˆ1,ˆ2))]. (2.5)

    Next, from

    db(ˆ2,˜Tˆ2Λ)Hb(˜Tˆ1Λ,˜Tˆ2Λ)<h2Hb(˜Tˆ1Λ,˜Tˆ2Λ),

    by Lemma 1.3, there exists ˆ3˜Tˆ2Λ such that db(ˆ2,ˆ3)h2Hb(˜Tˆ1Λ,˜Tˆ2Λ). By (2.5), this inequality gives that

    φ[(db(ˆ2,ˆ3))]φ[h2Hb(˜Tˆ1Λ,˜Tˆ2Λ)]<φ[Ω(ˆ1,ˆ2))],

    where

    Ω(ˆ1,ˆ2)=max{db(ˆ1,ˆ2),db(ˆ1,˜Tˆ1),db(ˆ2,˜Tˆ2),db(ˆ1,˜Tˆ2)+db(ˆ2,˜Tˆ1)2s}max{ˆd(ˆ1,ˆ2),ˆd(ˆ2,˜Tˆ2),ˆd(ˆ1,˜Tˆ2)2s}max{ˆd(ˆ1,ˆ2),ˆd(ˆ2,˜Tˆ2)}.

    This implies that

    φ[(ˆd(ˆ2,ˆ3)]φ[h1Hb(˜Tˆ1Λ,˜Tˆ2Λ)]<φ[ˆd(ˆ1,ˆ2))]. (2.6)

    Let Δ=max{db(ˆ1,ˆ2),db(ˆ2,˜Tˆ2)}. Assume that Δ=db(ˆ2,˜Tˆ2). Since ˆ3˜Tˆ2Λ, we have

    φ[(db(ˆ2,ˆ3)]φ[h1Hb(˜Tˆ1Λ,˜Tˆ2Λ)]<φ[db(ˆ2,ˆ3))],

    which is a contradiction. Hence (2.6) holds true. We assume that db(ˆ2,ˆ3)0, otherwise, ˆ2 is a fixed point of ˜T. From (φa), (2.6) implies that

    db(ˆ2,ˆ3)<db(ˆ1,ˆ2).

    and so db(ˆ2,ˆ3)E. Also, we have ˆ3¯b(ˆ0,ρ), since

    db(ˆ0,ˆ3)sdb(ˆ0,ˆ1)+s2db(ˆ1,ˆ2)+s3db(ˆ2,ˆ3)=s[db(ˆ0,ˆ1)+sˇdb(ˆ1,ˆ2)+s2db(ˆ2,ˆ3)]s[db(ˆ0,ˆ1)+ξ(db(ˆ0,ˆ1))+ξ2(db(ˆ0,ˆ1))]sσˇdb(ˆ0,ˆ1)db(ˆ0,ˆ1)+sσ(db(ˆ0,ˆ1))=σ(db(ˆ0,ˆ1))=ρ.

    Continuing this manner, we build two sequences {ˆi}¯b(ˆ0,ρ) and {hi}(0,+) such that ˆi+1˜TˆiΛ, ˆiˆi+1 with db(ˆi,ˆi+1)E and

    φ[(db(ˆi,ˆi+1))]φ[hiHb(˜Tˆi1Λ,˜TˆiΛ)]<φ[db(ˆi1,ˆi)],

    for all iN. Then

    φ[db(ˆi,ˆi+1)]φ[ξi(ˇdb(ˆ0,ˆ1))], foralliN.

    Since φ:(0,+)(0,+), it follows from (2.6) that

    0limi+φ[db(ˆi,ˆi+1)]limi+φ[ξi(db(ˆ0,ˆ1))]=0,

    which implies that

    limi+φ[db(ˆi,ˆi+1)]=0.

    By (φb) and Lemma 1.2, we have

    limi+ˇdb(ˆi,ˆi+1)=0. (2.7)

    Next, we prove that {ˆi} is a Cauchy sequence in ˆU. Arguing by contradiction, we assume that there are ϵ>0 and sequences {δi}+i=1 and {κi}+i=1 of natural numbers such that

    δi>κi>0,db(ˆδi,ˆκi)ϵanddb(ˆδi1,ˆκi)<ϵforalliN.

    Therefore,

    ϵdb(ˆδi,ˆκi)s[db(ˆδi,ˆδi1)+db(ˆδi1,ˆκi)]sˇdb(ˆδi,ˆδi1)+sϵ. (2.8)

    Setting i+ in (2.8),

    ϵ<limi+db(ˆδi,ˆκi)<sϵ. (2.9)

    From the trianguler inequality, we have

    db(ˆδi,ˆκi)db(ˆδi,ˆδi+1)+db(ˆδi+1,ˆκi) (2.10)

    and

    db(ˆδi+1,ˆκi)s[ˇdb(ˆδi,ˆδi+1)+db(ˆδi,ˆκi)]. (2.11)

    Letting the upper limit as i+ in (2.10) and applying (2.7) and (2.9), we obtain

    ϵlimi+supdb(ˆδi,ˆκi)s[limi+supdb(ˆδi+1,ˆκi)].

    Again, setting the upper limit as i+ in (2.11), we get

    limi+supdb(ˆδi+1,ˆκi)s[limi+supdb(ˆδi,ˆκi)]s.sϵ=s2ϵ.

    Therefore,

    ϵslimi+supdb(ˆδi+1,ˆκi)s2ϵ, (2.12)

    equivalently, we have

    ϵslimi+supdb(ˆδi,ˆκi+1)s2ϵ. (2.13)

    By the trianguler inequality,

    ˇdb(ˆδi+1,ˆκi)s[db(ˆδi+1,ˆκi+1)+db(ˆκi+1,ˆκi)]. (2.14)

    Setting the limit as i+ in (2.14), using (2.7) and (2.12), we have

    ϵs2limi+supdb(ˆδi+1,ˆκi+1). (2.15)

    Owing to above process, we find

    limi+supˇdb(ˆδi+1,ˆκi+1)s3ϵ. (2.16)

    From (2.15) and (2.16), we have

    ϵs2limi+supdb(ˆδi+1,ˆκi+1)s3ϵ.

    Owing to (2.7) and (2.9), we can choose a positive integer j01 such that

    12smin{db(ˆδi,˜TˆδiΛ),db(ˆκi,˜TˆκiΛ)}<ϵ2s<ˇdb(ˆδi,ˆκi)

    for all ij0. From (2.1), we have

    0<φ[db(ˆδi+1,ˆκi+1)]φ[Hb(˜TˆδiΛ,˜TˆκiΛ)]φ[ξ(Ω(ˆδi,ˆκi)))],

    where

    Ω(ˆδi,ˆκi)=max{db(ˆδi,ˆκi),db(ˆδi,˜Tˆδi),db(ˆκi,˜Tˆκi),db(ˆδi,˜Tˆκi)+db(ˆκi,˜Tˆδi)2s}max{db(ˆδi,ˆκi),db(ˆδi,ˆδi+1),db(ˆκi,ˆκi+1),db(ˆδi,ˆκi+1)+db(ˆκi,ˆδi+1)2s}.

    Setting the limit as i+ and by (2.7), (2.9), (2.12) and (2.13), we have

    ϵ=max{ϵ,12s(ϵs+ϵs)}limi+supΩ(ˆδi,ˆκi)max{sϵ,12s(s2ϵ+s2ϵ)}=sϵ.

    By (2.15) and (φb), we have

    φ[sϵ]=φ[ϵs2]limi+supˇdb(ˆδi+1,ˆκi+1)limi+φ[ξdb(ˆδi,ˆκi)]=φ[ξ(sϵ)]<φ[sϵ],

    which is a contradiction. Therefore, we deduce that {ˆi} is a Cauchy sequence in the closed ball ¯b(ˆ0,ρ). Since ¯b(ˆ0,ρ) is closed in ˆU, there exists a σ¯b(ˆ0,ρ) such that ˆiσ. Note that σΛ, since ˆi+1˜TˆiΛ. Next, we claim that

    12smin{db(ˆi,˜TˆiΛ),db(σ,˜TσΛ)}<db(ˆi,σ), (2.17)

    or

    12smin{ˇdb(σ,˜TσΛ),db(ˆi+1,˜Tˆi+1Λ)}<db(ˆi+1,σ)

    for all iN. Assume, on contrary, there exists iN such that

    12smin{db(ˆi,˜TˆiΛ),ˇdb(σ,˜TσΛ)}db(ˆi,σ) (2.18)

    and

    12smin{db(σ,˜TσΛ),db(ˆi+1,˜Tˆi+1Λ)}db(ˆi+1,σ). (2.19)

    By (2.18), we have

    2sˇdb(ˆi,σ)min{db(ˆi,˜TˆiΛ),db(σ,˜TσΛ)}min{s[db(ˆi,σ)+db(σ,˜TˆiΛ)],ˇdb(σ,˜TσΛ)}s[db(ˆi,σ)+db(σ,˜TˆiΛ)]<s[db(ˆi,σ)+ˇdb(σ,˜Tˆi)]s[db(ˆi,σ)+db(σ,ˆi+1)],

    which implies that

    db(ˆi,σ)db(σ,ˆi+1).

    This together with (2.19) implies

    db(ˆi,σ)db(σ,ˆi+1)12smin{db(σ,˜TσΛ),db(ˆi+1,˜Tˆi+1Λ)}. (2.20)

    So

    12smin{db(ˆi,˜TˆiΛ),ˇdb(ˆi+1,˜Tˆi+1Λ)}<db(ˆi,ˆi+1).

    From the contractive condition (2.1), we have

    0<φ[db(ˆi+1,ˆi+2)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]φ[ξ(c(ˆi,ˆi+1)))],

    where

    Ω(ˆi,ˆi+1)=max{db(ˆi,ˆi+1),db(ˆi,˜Tˆi),ˇdb(ˆi+1,˜Tˆi+1),db(ˆi,˜Tˆi+1)+db(ˆi+1,˜Tˆi)2s}max{db(ˆi,ˆi+1),ˇdb(ˆi+1,ˆi+2),db(ˆi,ˆi+2)2s}max{db(ˆi,ˆi+1),db(ˆi+1,ˆi+2)},

    which yields

    φ[ˇdb(ˆi+1,ˆi+2)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]<φ[db(ˆi,ˆi+1))].

    Let Δ=max{db(ˆi,ˆi+1),db(ˆi+1,ˆi+2)}. Assume that Δ=db(ˆi+1,ˆi+2). Since ˆi+2˜Tˆi+1Λ, we have

    φ[db(ˆi+1,ˆi+2)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]<φ[db(ˆi+1,ˆi+2))],

    which is a contradiction. Owing to (φa), we have

    ˇdb(ˆi+1,ˆi+2)<db(ˆi,ˆi+1). (2.21)

    From (2.19), (2.20) and (2.21), we obtain

    db(ˆi+1,ˆi+2)<db(ˆi,ˆi+1)s[ˇdb(ˆi,σ)+db(σ,ˆi+1)][12min{db(σ,˜TσΛ),db(ˆi+1,˜Tˆi+1Λ)}+12min{ˇdb(σ,˜TσΛ),db(ˆi+1,˜Tˆi+1Λ)}]min{db(σ,˜TσΛ),db(ˆi+1,ˆi+2)}=db(ˆi+1,ˆi+2),

    which is a contradiction. Hence (2.17) holds true, that is,

    12smin{ˇdb(ˆi,˜TˆiΛ),db(σ,˜TσΛ)}<db(ˆi,σ)foralli2. (2.22)

    Owing to (2.22), we have

    12smin{db(ˆi,˜TˆiΛ),db(ˆi+1,˜Tˆi+1Λ)}<db(ˆi,ˆi+1).

    Moreover, we know that db(ˆi,ˆi+1)E for all i. Thus, from (2.1), we have

    φ[db(ˆi+1,˜Tˆi+1Λ)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]φ[ξ(Ω(ˆi,ˆi+1)))]<φ[Ω(ˆi,ˆi+1)))],

    where

    Ω(ˆi,ˆi+1)=max{db(ˆi,ˆi+1),db(ˆi,˜Tˆi),db(ˆi+1,˜Tˆi+1),db(ˆi,˜Tˆi+1)+db(ˆi+1,˜Tˆi)2s}max{db(ˆi,ˆi+1),db(ˆi+1,ˆi+2),db(ˆi,ˆi+2)2s}max{db(ˆi,ˆi+1),db(ˆi+1,ˆi+2)},

    which implies

    φ[db(ˆi+1,ˆi+2)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]<φ[db(ˆi,ˆi+1))].

    Let Δ=max{db(ˆi,ˆi+1),db(ˆi+1,ˆi+2)}. Assume that Δ=db(ˆi+1,ˆi+2). Since ˆi+2˜Tˆi+1Λ, we have

    φ[db(ˆi+1,ˆi+2)]φ[Hb(˜TˆiΛ,˜Tˆi+1Λ)]<φ[db(ˆi+1,ˆi+2))],

    which is a contradiction. Also, by (φa), we deduce that

    db(ˆi+1,˜Tˆi+1Λ)<db(ˆi,ˆi+1). (2.23)

    Taking the limit i+ in (2.23), we get

    limi+db(ˆi+1,˜Tˆi+1Λ)=0.

    Since g(ˆ)=db(ˆ,˜TˆΛ) is ˜T-o.l.s.c at σ,

    db(σ,˜TσΛ)=g(σ)lim infig(ˆi+1)=lim infidb(ˆi+1,˜Tˆi+1Λ)=0.

    Since ˜Tσ is closed, we have σ˜Tσ. Conversely, if σ is a fixed point of ˜T then g(σ)=0lim infig(ˆi), since σΛ.

    Corollary 2.3. Let (ˆU,db) be a b-metric space with s1, Λ be a closed subset of ˆU and ξ be a b-B-GGF on an interval E. A mapping ˜T:ΛCB(ˆU) is said to be a multivalued SU-type φ-contraction if there exists φφ such that for ˜TˆΛ

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    φ[Hb(˜TˆΛ,˜TνΛ)]φ[ξ((ˆ,ν)))],

    for all ˆΛ, ν˜TˆΛ with db(ˆ,ν)E, where Hb(˜TˆΛ,˜TνΛ)>0. Assume ˆ0Λ such that db(ˆ0,c)E for some c˜Tˆ0Λ. Then there exist an orbit {ˆi} of ˜T in Λ and σΛ such that limi+ˆi=σ. Moreover, σ is a fixed point of ˜T if and only if the function g(ˆ):=db(ˆ,˜TˆΛ) is ˜T-o.l.s.c at σ.

    Corollary 2.4. Let (ˆU,db) be a b-metric space with s1, Λ be a closed subset of ˆU and ξ be a b-B-GGF on an interval E. A mapping ˜T:ΛCB(ˆU) is said to be a multivalued SU-type φ-contraction if there exists φφ such that for ˜TˆΛ

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    φ[Hb(˜TˆΛ,˜TνΛ)]φ[ξ(db(ˆ,ν)))],

    for all ˆˆU, ν˜Tˆ with db(ˆ,ν)E. Suppose that ˆ0ˆU such that db(ˆ0,c)E for some c˜Tˆ0. Then there exists an orbit {ˆi} of ˜T in ˆU which converges to the fixed point σF={ˆˆU:db(ˆ,σ)E} of ˜T.

    Example 2.5. Let ˆU=[0,1] be endowed with the metric db with coefficient sα2+7α21>1 [where α3 is any positive integers] as defined by db(ˆ,ν)=|ˆν|2 for all ˆ,νˆU but not a metric bd. For ˆ1=0, ˆ2=12 and ˆ3=1, we obtain

    bd(ˆ1,ˆ3)=1>14+14=bd(ˆ1,ˆ2)+bd(ˆ2,ˆ3)

    and let E=[0,+). Consider the mapping ˜T:ˆUCB(ˆU) defined by ˜T(ˆ)=[0,ˆ2]. Clearly,

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    if and only if ˆ,ν[0,1]. Let ˆ0=1. Then we have c=12˜Tˆ0 such that db(ˆ0,c)E and

    φ[Hb(˜Tˆ,˜Tν)]=φ[|ˆ2ν2|2]φ[|ˆ+ν|2db(ˆ,ν)].

    Set φ(r)=rer for all r>0 and suppose that ξ(r)=r2 is a b -B-GGF of order 2 on E=[0,1α1] with coefficient α2+7α21. For any ˆ[0,1] and ν˜Tˆ, we get

    φ[Hb(˜Tˆ,˜Tν)][|ˆ+ν|2db(ˆ,ν)]e[|ˆ+ν|2db(ˆ,ν)]=φ[ξ(db(ˆ,ν))].

    Thus, all the conditions of Corollary 2.3 are fulfilled and 0 is a fixed point of ˜T.

    In this section, motivated by the notion of multivalued Suzuki type -contraction, we define the notion of multivalued Suzuki type (αξ)-contraction as follows:

    Definition 3.1. Let (ˆU,db) be a b-metric space with s1, Λ be a closed subset of ˆU and ξ be a b-B-GGF on an interval E. A mapping ˜T:ΛCB(ˆU) is said to be a multivalued Suzuki type (αξ)-contraction if there exists Γ such that for ˜TˆΛ

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    Γ[α(ˆ,ν)Hb(˜TˆΛ,˜TνΛ),ξ(Ω(ˆ,ν))]0, (3.1)

    where

    Ω(ˆ,ν)=max{db(ˆ,ν),db(ˆ,˜Tˆ),db(ν,˜Tν),db(ˆ,˜Tν)+db(ν,˜Tˆ)2s}

    for all ˆΛ, ν˜TˆΛ with db(ˆ,ν)E.

    The second one of our results is as follows.

    Theorem 3.2. Let (ˆU,db) be a complete b-metric space with s1, Λ be a closed subset of ˆU and ˜T:ΛCB(ˆU) be a multivalued SU-type (α-)-contraction. Suppose that the following conditions are satisfied:

    (i) ˜T is α-admissible;

    (ii) there exists ˆ0Λ with db(ˆ0,ˆ1)E for some ˆ1˜Tˆ0Λ such that α(ˆ0,ˆ1)1.

    Then there exist an orbit {ˆi} of ˜T in Λ and σΛ such that limi+ˆi=σ. Moreover, σ is a fixed point of ˜T if and only if the function g(ˆ):=db(ˆ,˜TˆΛ) is ˜T-o.l.s.c at σ.

    Proof. Owing to the hypothesis, there exists ˆ0Λ with db(ˆ0,ˆ1)E for some ˆ1˜Tˆ0Λ such that α(ˆ0,ˆ1)1. On the other hand, we have

    12smin{db(ˆ0,˜Tˆ0Λ),db(ˆ1,˜Tˆ1Λ)}<db(ˆ0,ˆ1). (3.2)

    If db(ˆ0,ˆ1)=0, then ˆ0 is a fixed point of ˜T. Thus, we assume that db(ˆ0,ˆ1)0. Define ρ=σ(db(ˆ0,ˆ1)). From (1.16), we have σ(r)r. Hence db(ˆ0,ˆ1)ρ and so ˆ1¯b(ˆ0,ρ). Since α(ˆ0,ˆ1)1 and db(ˆ0,ˆ1)E, from (3.1) and (3.2), it follows that

    0Γ[α(ˆ0,ˆ1)Hb(˜Tˆ0Λ,˜Tˆ1Λ),ξ(db(ˆ0,ˆ1))]<ξ(Ω(ˆ0,ˆ1))α(ˆ0,ˆ1)Hb(˜Tˆ0Λ,˜Tˆ1Λ),

    which implies

    α(ˆ0,ˆ1)Hb(˜Tˆ0Λ,˜Tˆ1Λ)<ξ(Ω(ˆ0,ˆ1)).

    We can choose an ϵ1>0 such that

    α(ˆ0,ˆ1)Hb(˜Tˆ0Λ,˜Tˆ1Λ)+ϵ1ξ(Ω(ˆ0,ˆ1)).

    Thus

    db(ˆ1,˜Tˆ1Λ)+ϵ1Hb(˜Tˆ0Λ,˜Tˆ1Λ)+ϵ1α(ˆ0,ˆ1)Hb(˜Tˆ0Λ,˜Tˆ1Λ)+ϵ1ξ(Ω(ˆ0,ˆ1)). (3.3)

    It follows from Lemma 1.2 that there exists ˆ2˜Tˆ1Λ such that

    db(ˆ1,ˆ2)db(ˆ1,˜Tˆ1Λ)+ϵ1. (3.4)

    From (3.3) and (3.4), we have

    db(ˆ1,ˆ2)ξ(Ω(ˆ0,ˆ1)),

    where

    Ω(ˆ0,ˆ1)=max{db(ˆ0,ˆ1),db(ˆ0,˜Tˆ0),db(ˆ1,˜Tˆ1),db(ˆ0,˜Tˆ1)+db(ˆ1,˜Tˆ0)2s}max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1),db(ˆ0,˜Tˆ1)2s}max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1)}.

    We claim that

    db(ˆ1,ˆ2)ξ(db(ˆ0,ˆ1)). (3.5)

    Let Δ=max{db(ˆ0,ˆ1),db(ˆ1,˜Tˆ1)}. Assume that Δ=db(ˆ1,˜Tˆ1). Since ˆ2˜Tˆ1Λ, we have

    (db(ˆ1,ˆ2)ξ(db(ˆ1,ˆ2)),

    which is a contradiction. Hence (3.5) holds true. We assume that db(ˆ1,ˆ2)0, otherwise, ˆ1 is a fixed point of ˜T. Since db(ˆ1,ˆ2)ξ(db(ˆ0,ˆ1))<db(ˆ0,ˆ1), we deduce that db(ˆ1,ˆ2)E. Next, ˆ2¯b(ˆ0,ρ) since

    db(ˆ0,ˆ2)sdb(ˆ0,ˆ1)+sdb(ˆ1,ˆ2)sdb(ˆ0,ˆ1)+s2db(ˆ1,ˆ2)sdb(ˆ0,ˆ1)+s2ξ(db(ˆ0,ˆ1))=s[db(ˆ0,ˆ1)+sξ(db(ˆ0,ˆ1))]sσdb(ˆ0,ˆ1)db(ˆ0,ˆ1)+sσ(db(ˆ0,ˆ1))=σ(db(ˆ0,ˆ1))=ρ..

    Since ˜T is α-admissible, α(ˆ1,ˆ2)1. Also, since

    12smin{db(ˆ1,˜Tˆ1Λ),db(ˆ2,˜Tˆ2Λ)}<db(ˆ1,ˆ2),

    from the contractive condition (3.1), we get

    0Γ[α(ˆ1,ˆ2)Hb(˜Tˆ1Λ,˜Tˆ2Λ),ξ(Ω(ˆ1,ˆ2))]<ξ(Ω(ˆ1,ˆ2))α(ˆ1,ˆ2)Hb(˜Tˆ1Λ,˜Tˆ2Λ).

    This implies that

    α(ˆ1,ˆ2)Hb(˜Tˆ1Λ,˜Tˆ2Λ)<ξ(Ω(ˆ1,ˆ2)).

    Now choose an ϵ2>0 such that

    α(ˆ1,ˆ2)Hb(˜Tˆ1Λ,˜Tˆ2Λ)+ϵ2ξ(Ω(ˆ1,ˆ2)).

    Thus,

    db(ˆ2,˜Tˆ2Λ)+ϵ2Hb(˜Tˆ1Λ,˜Tˆ2Λ)+ϵ2α(ˆ1,ˆ2)Hb(˜Tˆ1Λ,˜Tˆ2Λ)+ϵ2ξ(Ω(ˆ1,ˆ2)). (3.6)

    It follows from Lemma 1.2 that there exists ˆ3˜Tˆ2Λ such that

    db(ˆ2,ˆ3)db(ˆ2,˜Tˆ2Λ)+ϵ2. (3.7)

    From (3.6) and (3.7), we obtain

    db(ˆ2,ˆ3)ξ(Ω(ˆ1,ˆ2)),

    where

    Ω(ˆ1,ˆ2)=max{db(ˆ1,ˆ2),db(ˆ1,˜Tˆ1),db(ˆ2,˜Tˆ2),db(ˆ1,˜Tˆ2)+db(ˆ2,˜Tˆ1)2s}max{db(ˆ1,ˆ2),db(ˆ2,˜Tˆ2),db(ˆ1,˜Tˆ2)2s}max{db(ˆ1,ˆ2),db(ˆ2,˜Tˆ2)}.

    This implies that

    db(ˆ2,ˆ3)ξdb(ˆ1,ˆ2)). (3.8)

    Let Δ=max{db(ˆ1,ˆ2),db(ˆ2,˜Tˆ2)}. Assume that Δ=db(ˆ2,˜Tˆ2). Since ˆ3˜Tˆ2Λ, we have

    db(ˆ2,ˆ3)ξˆd(ˆ2,ˆ3)),

    which is a contradiction. Hence (3.8) holds true. We assume that db(ˆ2,ˆ3)0, otherwise, ˆ2 is a fixed point of ˜T. From (3.8), we have db(ˆ2,ˆ3)<db(ˆ1,ˆ2) and so db(ˆ2,ˆ3)E. Also, we have ˆ3¯b(ˆ0,ρ), since

    db(ˆ0,ˆ3)sdb(ˆ0,ˆ1)+s2db(ˆ1,ˆ2)+s3db(ˆ2,ˆ3)=s[db(ˆ0,ˆ1)+sdb(ˆ1,ˆ2)+s2db(ˆ2,ˆ3)]s[db(ˆ0,ˆ1)+ξ(db(ˆ0,ˆ1))+ξ2(db(ˆ0,ˆ1))]sσdb(ˆ0,ˆ1)db(ˆ0,ˆ1)+sσ(db(ˆ0,ˆ1))=σ(db(ˆ0,ˆ1))=ρ.

    Continuing this manner, we obtain a sequence {ˆi}¯b(ˆ0,ρ) such that ˆi+1˜TˆiΛ, ˆiˆi+1 with α(ˆi,ˆi+1)1, db(ˆi,ˆi+1)E and by the above hypothesis, we have

    db(ˆi,ˆi+1)ξi(db(ˆ0,ˆ1)),  foralliN. (3.9)

    For any qN, by using the triangular inequality and (3.9), we get

    db(ˆi,ˆi+q)sidb(ˆi,ˆi+1)+si+1db(ˆi+1,ˆi+2)++si+q1db(ˆi+q1,ˆi+q)siξi(db(ˆ0,ˆ1))+si+1ξi+1(db(ˆ0,ˆ1))++si+q1ξi+q1(db(ˆ0,ˆ1))j=isjξj(db(ˆ0,ˆ1))<. (3.10)

    Assume that

    Hi=j=isjξj(db(ˆ0,ˆ1))andlimi+Hi=H. (3.11)

    By (3.10) and (3.11), we get

    db(ˆi,ˆi+q)(Hi+q1Hi). (3.12)

    Due to (3.11), (3.12) implies that db(ˆi,ˆi+q)0 as i+. Hence {ˆi} is a Cauchy sequence in the closed ball ¯b(ˆ0,ρ). Since ¯b(ˆ0,ρ) is closed in ˆU, there exists an σ¯b(ˆ0,ρ) such that ˆiσ. Note that σΛ, since ˆi+1˜TˆiΛ. By the same argument as in Theorem 2.2, we have

    12smin{db(ˆi,˜TˆiΛ),db(ˆi+1,˜Tˆi+1Λ)}<db(ˆi,ˆi+1).

    Also, we know that α(ˆi,ˆi+1)1 and db(ˆi,ˆi+1)E for all n. Thus, from (3.1), we have

    0Γ[α(ˆi,ˆi+1)Hb(˜TˆiΛ,˜Tˆi+1Λ),ξ(Ω(ˆi,ˆi+1))]<ξ(Ω(ˆi,ˆi+1))α(ˆi,ˆi+1)Hb(˜TˆiΛ,˜Tˆi+1Λ),

    which gives that

    α(ˆi,ˆi+1)Hb(˜TˆiΛ,˜Tˆi+1Λ)<ξ(Ω(ˆi,ˆi+1)).

    Since ˆi+1˜TˆiΛ, from (3.9), we get

    db(ˆi+1,˜Tˆi+1Λ)α(ˆi,ˆi+1)Hb(˜TˆiΛ,˜Tˆi+1Λ)<ξ(db(ˆi,ˆi+1))ξi+1(db(ˆ0,ˆ1)). (3.13)

    Taking the limit i+ in (3.13), we obtain

    limi+db(ˆi+1,˜Tˆi+1Λ)=0.

    Since g(ˆ)=db(ˆ,˜TˆΛ) is ˜T-orbitally lower semi-continuous at σ,

    db(σ,˜TσΛ)=g(σ)lim infig(ˆi+1)=lim infiˇdb(ˆi+1,˜Tˆi+1Λ)=0.

    Since ˜Tσ is closed, we have σ˜Tσ. Conversely, if σ is a fixed point of ˜T then g(σ)=0lim infig(ˆi), since σΛ.

    Setting Γ(r,s)=sr0ς(t)dtforallr,s0 in Theorem 3.2, we get the following result.

    Corollary 3.3. Let (ˆU,db) be a complete b-metric space with s1, Λ be a closed subset of ˆU, ξ be a b-B-GGF on an interval E and let ˜T:ΛCB(ˆU) be a given multivalued mapping. Suppose that for ˜TˆΛ such that

    12smin{db(ˆ,˜TˆΛ),db(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    α(ˆ,ν)Hb(˜TˆΛ,˜TνΛ)0ς(t)dtξ(ˆd(ˆ,ν))

    for all ˆΛ, ν˜TˆΛ with ˆd(ˆ,ν)E, where ς:R+R+ is a function such that ϵ0ς(t)dt exists and ϵ0ς(t)dt>ϵ for all ϵ>0. Suppose that the following conditions are satisfied:

    (i) ˜T is α-admissible;

    (ii) there exists ˆ0Λ with db(ˆ0,ˆ1)E for some ˆ1˜Tˆ0Λ such that α(ˆ0,ˆ1)1.

    Then there exist an orbit {ˆi} of ˜T in Λ and σΛ such that limi+ˆi=σ. Moreover, σ is a fixed point of ˜T if and only if the function g(ˆ):=db(ˆ,˜TˆΛ) is ˜T-o.l.s.c at σ.

    Corollary 3.4. Let (ˆU,db) be a complete b-metric space with s1, ξ be b -B-GGF on an interval E and let ˜T:ˆUCB(ˆU) be a given multivalued mapping. Suupose that there exist ψΦ and Γ such that

    12smin{db(ˆ,˜TˆΛ),ˇdb(ν,˜TνΛ)}<db(ˆ,ν)

    implies that

    Γ[α(ˆ,ν)Hb(˜Tˆ,˜Tν),ξ(db(ˆ,ν))]0

    for all ˆˆU, ν˜Tˆ with db(ˆ,ν)E. Suppose that the following conditions are satisfied:

    (i) ˜T is α-admissible;

    (ii) there exists ˆ0ˆU with db(ˆ0,ˆ1)E for some ˆ1˜Tˆ0 such thatα(ˆ0,ˆ1)1.

    Then there exists an orbit {ˆi} of ˜T in ˆU which converges to the fixed point σF={ˆˆU:db(ˆ,σ)E} of ˜T.

    In the recent past, Banach's fixed point theorem has a broad family of important applications to an iteration methods for the system of linear algebraic equation and the most publicized application of Banach's fixed point theorem emarge in the module of function spaces. This yields the existence of solution for the system of differential and integral equations (see [3]). In this section, we investigate Corollary 2.4 to stabilize the existence of solution for the system of integral inclusions.

    Consider the following system of integral inclusion:

    ς(r)κ+Urr0D(t,ς(t))dt, (4.1)

    where κ(,+), U is a bounded compact subset of (,+) and the operator D(t,ς(t)) is lower semi-continuous. Let ˆU=C(I) be the space of all continuous real valued functions (C(I) is complete with respect to the metric db) endowed with the b-metric defined by

    db(ˆ1,ˆ2)=suprI|ˆ1(r)ˆ2(r)|.

    Assume that there exists D:(,+)×(,+)(,+) which is continuous on

    Γ={(r,ς):|rr0|[αh21αh11]and|ςκ|12(α2α1)}

    where α1=maxuU|U|, 0<α2<α1 and h2 such that

    |D(r,ς1(r))D(r,ς2(r))|α1α2|ς1(r)ς2(r)|h,

    where D is bounded as

    |D(t,ς)|<12[α2α1]h.

    Moreover, let ˇC={ςC(I):ˆV(ς,κ)12α2} be a closed subspace of C(I) and the operator g be defined by

    g(ς(r))κ+Urr0V(t,ς(t))dt.

    Set VˆU(r)=rr0V(t,ς(t))dt. Note that

    Hb[g(ς1(r)),g(ς2(r))]=Hb[κ+UVˆU(r),κ+UVy(r)]Hb[UVˆU(r),UVy(r)]=max{max¯aUVˆU(r)ˇdb(¯a,UVy(r)),max¯bUVy(r)db(¯b,UVˆU(r))}. (4.2)

    Then

    max¯aUVˆU(r)db(¯a,UVy(r))=max¯aUVˆU(r)min¯bUVy(r)db(¯a,¯b)=max¯uUmin¯vUˇdb(¯uV(r,ς1(r)),¯vV(r,ς2(r)))=max¯uUmin¯vUsuprI|¯uV(r,ς1(r))¯vV(r,ς2(r))|max¯uUmin¯vUsuprI[|¯uV(r,ς2(r))¯vV(r,ς2(r))|+|¯uV(r,ς2(r))¯uV(r,ς1(r))|]max¯uUmin¯vU[|¯u|suprI|V(r,ς2(r))V(r,ς1(r))|+|¯u¯v|suprI|V(r,ς2(r))|]=max¯uU|¯u|suprI|V(r,ς2(r))V(r,ς1(r))|=α2suprI|V(r,ς2(r))V(r,ς1(r))|.

    This implies that

    max¯aUVˆU(r)d(¯a,UVy(r))α2suprI|V(r,ς2(r))V(r,ς1(r))|. (4.3)

    The third one of our results is as follows:

    Theorem 4.1. Let ˆU=C(I) be the space of all continuous real valued functions and g:(ˇC,d)(V(ˇC),Hb) be a lower semi-continuous mapping. Suppose that the following assumptions hold:

    (i) g is defined for all ςˇC;

    (ii) g(ς(r)) is a compact subset of ˇC for all ςˇC;

    Then the integral equation (4.3) has a solution on

    I=[r0αh21αh11,r0+αh21αh11].

    Proof. Let ϰI. Then |ϰr0|[αh21αh11]. Hence we have |ς(ϰ)κ|12(α2α1). If (ϰ,ς(ϰ))(,+), then the integral equation in (4.1) exists. Since κ(,+) is continuous, ϰ is defined for all ϰˇC. Next, let ϑ(r)g(ς(r)). Then ϑ(r)=κ+¯uVˆU(r) for ¯uU and so

    |ϑ(r)κ|=|¯uVˆU(r)|=|¯u||VˆU(r)|α1rr0|V(t,ς(t))dt|α1rr0|V(t,ς(t))|dt<α112(α2α1)h12(α2α1).

    Thus |ϑ(r)κ|12(α2α1) for all ϑ(r)g(ς(r)). So g(ς(r)) is a subset of ˇC. Now, let {ςi}g(ς(r)). Then ς=κ+¯uiDˆU(r) for ¯uiU. Since U is compact, there exists a subsequence ^ui^ui such that {^ui} is convergent to ¯uU. Let ˆu=κ+ˆuVˆU(r). Then

    d(^ui,ˆu)=suprI(|^uiˆu||VˆU(r)|)|^uiˆu|suprI|VˆU(r)|0,asi+.

    Hence g(ς(r)) is a compact subset of ˇC for all ςˇC. Next,

    |V(r,ς1(r))V(r,ς2(r))|rr0|V(t,ς1(t))V(t,ς2(t))|dtα2α1rr0|ς1(t)ς2(t)|hdtα2α1suprI|ς1(t)ς2(t)|hrr0dt=α2α1|rr0|[db(ς1,ς2)]h1α1(α1α2)h2[db(ς1,ς2)]h.

    Therefore, we get

    max¯aUVˆU(r)db(¯a,UVy(r))(α1α2)h2[db(ς1,ς2)]h.

    Similarly,

    max¯bUVy(r)db(¯b,UVˆU(r))(α1α2)h2[db(ˆ1,ˆ2)]h.

    Hence (4.2) implies that

    Hb[db(g(ϖ1),g(ϖ2))](α1α2)h2[ˇdb(ς1,ς2)]h.

    Taking φ(ς)=ς, ς>0 and ξ(ς)=(α1α2)h2ςh, ςE with db(ς1,ς2)<α2α1, we get

    φ[Hbdb(g(ϖ1),g(ϖ2))]φ[ξ(db(ϖ1,ϖ2))]forall;ϖ1,ϖ2ˇCwithdb(ς1,ς2)E.

    Hence the requied conditions (i)-(ii) are equivalent to (a)-(b) of Corollary 2.3. So there exists a fixed point c(Λ) in ˇC, which is a bounded solution of (4.1).

    The paper deals with the pre-existing results of fixed point for multi-valued maps satisfying φ-contraction via b-B-GGF in the context of b-metric space. Within this frame work, we introduced two related fixed point results in b-metric space. Afterwards, the results have been explained by rendering concrete examples and some foremost corollaries have been deduced from the main results. At the end, we have proved existence theorem for the system of multi-valued integral inclusion.

    We would like to express our sincere gratitude to the anonymous referee for his/her helpful comments that will help to improve the quality of the manuscript.

    The authors declare that they have no competing interests.



    [1] A. Ali, H. Işık, H. Aydi, E. Ameer, J. Lee, M. Arshad, On multivalued Suzuki-type θ-contractions and related applications, Open Math., 18 (2020), 386–399. doi: 10.1515/math-2020-0139
    [2] A. Ali, H. Işık, F. Uddin, M. Arshad, Fixed point results for Su-type contractive mappings with an application, JLTA, 9 (2020), 53–65.
    [3] A. Ali, F. Uddin, M. Arshad, M. Rashid, Hybrid fixed point results via generalized dynamic process for F-HRS type contractions with application, Physica A, 538 (2020), 122669. doi: 10.1016/j.physa.2019.122669
    [4] A. Asif, M. Alansari, N. Hussain, M. Arshad, A. Ali, Iterating fixed point via generalized Mann's iteration in convex b-metric spaces with application, Complexity, 2021 (2021), 8534239.
    [5] M. U. Ali, T. Kamran, E. Karapınar, A new approach to (α,ψ)-contractive nonself multivalued mappings, J. Inequal. Appl., 2014 (2014), 1–9. doi: 10.1186/1029-242X-2014-1
    [6] S. Aleksić, H. Huang, Z. D. Mitrović, S. Radenovic, Remarks on some fixed point results in b-metric spaces, J. Fix. Point Theory A., 20 (2018), 1–17. doi: 10.1007/s11784-018-0489-6
    [7] R. M. Bianchini, M. Grandolfi, Trasformazioni di tipo contrattivo generalizzato in uno spazio metrico, Atti Accad. Naz. Lincei, Rend. Cl. Sci. Fis. Mat. Nat., 45 (1968), 212–216.
    [8] S. Czerwik, Nonlinear set-valued contraction mappings in b-metric spaces, Atti. Sem. Mat. Fis. Univ. Modena, 46 (1998), 263–276.
    [9] Y. U. Gaba, E. Karapinar, A. Petruşel, S. Radenović, New results on start-points for multi-valued maps, Axioms, 9 (2020), 1–11. doi: 10.30821/axiom.v9i1.7235
    [10] S. Ivković, On upper triangular operator 2×2 matrices over C-algebras, Filomat, 34 (2020), 691–706. doi: 10.2298/FIL2003691I
    [11] F. Khojasteh, S. Shukla, S. Radenović, A new approach to the study of fixed point theoremetric space via simulation functions, Filomat, 29 (2015), 1189–1194. doi: 10.2298/FIL1506189K
    [12] X. D. Liu, S. S. Chang, Y. Xiao and L. C. Zhao, Some fixed point theorems concerning (ψ,ϕ)-type contraction in complete metric spaces, J. Nonlinear Sci. Appl., 9 (2016), 4127–4136. doi: 10.22436/jnsa.009.06.56
    [13] S. B. Nadler, Multi-valued contraction mappings, Pac. J. Math., 30 (1969), 475–488. doi: 10.2140/pjm.1969.30.475
    [14] P. D. Proinov, A generalization of the Banach contraction principle with high order of convergence of successive approximations, Nonlinear Anal. Theor., 67 (2007), 2361–2369. doi: 10.1016/j.na.2006.09.008
    [15] H. Qawaqneh, M. S. Noorani, W. Shatanawi, H. Aydi, H. Alsamir, Fixed point results for multi-valued contractions in b-metric spaces, Mathematics, 7 (2019), 1–13.
    [16] M. Samreen, Q. Kiran, T. Kamran, Fixed point theorems for φ-contractions, J. Inequal. Appl., 2014 (2014), 1–16. doi: 10.1186/1029-242X-2014-1
    [17] H. Sahin, M. Aslantas, I. Altun, Feng-Liu type approach to best proximity point results for multivalued mappings, J. Fix. Point Theory A., 22 (2020), 1–13. doi: 10.1007/s11784-019-0746-3
    [18] V. Todorčević, Harmonic quasiconformal mappings and hyperbolic type metrics, Springer International Publishing, 2019.
    [19] F. Vetro, A generalization of Nadler fixed point theorem, Carpathian J. Math., 31 (2015), 403–410. doi: 10.37193/CJM.2015.03.18
    [20] M. Zoran D., V. Parvaneh, N. Mlaiki, N. Hussain, S. Radenović, On some new generalizations of Nadler contraction in b-metric spaces, Cogent Mathematics & Statistics, 7 (2020), 1760189.
  • This article has been cited by:

    1. Muhammad Tariq, Mujahid Abbas, Aftab Hussain, Muhammad Arshad, Amjad Ali, Hamid Al-Sulami, Fixed points of non-linear set-valued $ \left(\alpha _{\ast }, \phi _{M}\right) $-contraction mappings and related applications, 2022, 7, 2473-6988, 8861, 10.3934/math.2022494
    2. Sumaiya Tasneem Zubair, Kalpana Gopalan, Thabet Abdeljawad, Nabil Mlaiki, Novel fixed point technique to coupled system of nonlinear implicit fractional differential equations in complex valued fuzzy rectangular $ b $-metric spaces, 2022, 7, 2473-6988, 10867, 10.3934/math.2022608
    3. Amjad Ali, Eskandar Ameer, Muhammad Arshad, Hüseyin Işık, Mustafa Mudhesh, Padmapriya Praveenkumar, Fixed Point Results of Dynamic Process D ˇ ϒ , μ 0 through F I C -Contractions with Applications, 2022, 2022, 1099-0526, 1, 10.1155/2022/8495451
    4. Amjad Ali, Muhammad Arshad, Eskandar Emeer, Hassen Aydi, Aiman Mukheimer, Kamal Abodayeh, Certain dynamic iterative scheme families and multi-valued fixed point results, 2022, 7, 2473-6988, 12177, 10.3934/math.2022677
    5. Maryam Iqbal, Afshan Batool, Aftab Hussain, Hamed Alsulami, Fuzzy Fixed Point Theorems in S-Metric Spaces: Applications to Navigation and Control Systems, 2024, 13, 2075-1680, 650, 10.3390/axioms13090650
    6. Amjad Ali, Muhammad Arshad, Eskandar Ameer, Asim Asiri, Certain new iteration of hybrid operators with contractive $ M $ -dynamic relations, 2023, 8, 2473-6988, 20576, 10.3934/math.20231049
  • Reader Comments
  • © 2021 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Metrics

Article views(2785) PDF downloads(125) Cited by(6)

/

DownLoad:  Full-Size Img  PowerPoint
Return
Return

Catalog