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Research article

A geometric formulation of Lax integrability for nonlinear equationsin two independent variables

  • Received: 20 October 2017 Accepted: 31 October 2017 Published: 06 November 2017
  • A geometric formulation of Lax integrability is introduced which makes use of a Pfaffan formulation of Lax integrability. The Frobenius theorem gives a necessary and suffcient condition for the complete integrability of a distribution, and provides a powerful way to study nonlinear evolution equations. This permits an examination of the relation between complete integrability and Lax integrability. The prolongation method is formulated in this context and gauge transformations can be examined in terms of differential forms as well as the Frobenius theorem.

    Citation: Paul Bracken. A geometric formulation of Lax integrability for nonlinear equationsin two independent variables[J]. AIMS Mathematics, 2017, 2(4): 610-621. doi: 10.3934/Math.2017.4.610

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  • A geometric formulation of Lax integrability is introduced which makes use of a Pfaffan formulation of Lax integrability. The Frobenius theorem gives a necessary and suffcient condition for the complete integrability of a distribution, and provides a powerful way to study nonlinear evolution equations. This permits an examination of the relation between complete integrability and Lax integrability. The prolongation method is formulated in this context and gauge transformations can be examined in terms of differential forms as well as the Frobenius theorem.


    Fixed point theory plays a fundamental role in mathematics and applied science, such as optimization, mathematical models and economic theories. Also, this theory has been applied to show the existence and uniqueness of the solutions of differential equations, integral equations and many other branches of mathematics, see [1,2]. A prominent result in fixed point theory is the Banach contraction principle [3]. Since the appearance of this principle, there has been a lot of activity in this area. Bakhtin [4] in 1989 introduced the notion of a b-metric space (Bms). Shoaib et. al [5] proved certain fixed point results in rectangular metric spaces. Multivalued mappings in various types of metric spaces have been extensively studied by many researchers to establish fixed point results and their applications, see for instance [6,7,8,9,10,11,12].

    In 1965, Zadeh [13] introduced the concept of a fuzzy set theory to deal with the unclear or inexplicit situations in daily life. Using this theory, Kramosil and Michálek [14] defined the concept of a fuzzy metric space (Fms). Grabiec [15] gave contractive mappings on a Fms and extended fixed point theorems of Banach and Edelstein in such a space. Successively, George and Veeramani [16] slightly modified the notion of a Fms introduced by Kramosil and Michálek [14] and then obtained a Hausdorff topology and a first countable topology on it. Many fixed point results have been established in a Fms. For instance, see [17,18,19,20,21,22,23,24,25] and the references therein. Recently, some coupled fuzzy fixed-point results on closed ball are established in fuzzy metric spaces [26]. The notion of generalized fuzzy metric spaces is studied in [27].

    The notion of a fuzzy b-metric space (Fbms) was defined in [28]. The notion of a Hausdorff Fms is introduced in [29]. Fixed point theory for multivalued mapping in fuzzy metric spaces has been extended in many directions. For a multivalued mapping (Mvp) in a complete Fms, some fixed point results are establish in [30]. Some fixed point results for a Mvp in a Hausdorff fuzzy b-metric space (Hfbms) are proved in [31]. In this article, we prove some fixed point results for a Mvp using Geraghty type contractions in a Hfbms. Results in [31,32] and [30] turn out to be special cases of our results.

    Throughout the article, refers to a non-empty set, N represents the set of natural numbers, R corresponds to the collection of real numbers, CB() and ˆC0() represent the collection of closed and bounded subsets and compact subsets of , respectively.

    Let us have a look at some core concepts that will be helpful for the proof of our main results.

    Definition 1.1. [33] For a real number b1, the triplet (,Θfb,) is called a Fbms on if for all ψ1,ψ2,ψ3 and γ>0, the following axioms hold, where is a continuous t-norm and Θfb is a fuzzy set on ××(0,):

    [Fb1:] Θfb(ψ1,ψ2,γ)>0;

    [Fb2:] Θfb(ψ1,ψ2,γ)=1 if and only if ψ1=ψ2;

    [Fb3:] Θfb(ψ1,ψ2,γ)=Θfb(ψ2,ψ1,γ);

    [Fb4:] Θfb(ψ1,ψ3,b(γ+β))Θfb(ψ1,ψ2,γ)Θfb(ψ2,ψ3,β) γ,β0;

    [Fb5:] Θfb(ψ1,ψ2,.):(0,)[0,1] is left continuous.

    The notion of a Fms in the sense of George and Veeramani [16] can be obtained by taking b=1 in the above definition.

    Example 1.1. For a Bms (,Θb,), define a mapping Θfb:××(0,)[0,1] by

    Θfb(ψ1,ψ2,γ)=γγ+db(ψ1,ψ1).

    Then (,Θfb,) is a Fbms.

    Following Grabiec [15], the notions of G-Cauchyness and completeness are defined as follows:

    Definition 1.2. [15]

    (i) If for a sequence {ψn} in a Fbms (,Θfb,), there is ψ such that

    limnΘfb(ψn,ψ,γ)=1,γ>0,

    then {ψn} is said to be convergent.

    (ii) If for a sequence {ψn} in a Fbms (,Θfb,), limnΘfb(ψn,ψn+q,γ)=1 then {ψn} is a G-Cauchy sequence for all γ>0 and positive integer q.

    (iii) A Fbms is G-complete if every G-Cauchy sequence is convergent.

    Definition 1.3. [30] Let B be any nonempty subset of a Fms (,Θfb,) and γ>0, then we define FΘfb(ϱ1,B,γ), the fuzzy distance between an element ϱ1 and the subset B, as follows:

    FΘfb(ϱ1,B,γ)=sup{Θf(ϱ1,ϱ2,γ):ϱ2B}.

    Note that FΘfb(ϱ1,B,γ)=FΘfb(B,ϱ1,α).

    Lemma 1.1. [31] Consider a Fbms (,Θfb,) and let CB() be the collection of closed bounded subsets of . If ACB() then ψA if and only if FΘfb(A,ψ,γ)=1γ>0.

    Definition 1.4. [31] Let (,Θfb,) be a Fbms. Define HFΘfb on ˆC0()׈C0()×(0,) by

    HFΘfb(A,B,γ)=min{ infψAFΘfb(ψ,B,γ),infϱBFΘfb(A,ϱ,γ)},

    for all A,B^C0() and γ>0.

    For Geraghty type contractions, follow [33] to define a class FΘb of all functions β:[0,)[0,1b) for b1, as

    FΘb={β:[0,)[0,1b)|limnβ(γn)=1blimnγn=0}. (1.1)

    Lemma 1.2. [31] Let (,Θfb,) be a G-complete Fbms. If ψ,ϱ and for a function βFΘfb

    Θfb(ψ,ϱ,β(Θfb(ψ,ϱ,γ))γ)Θfb(ψ,ϱ,γ),

    then ψ=ϱ.

    Lemma 1.3. [31] Let (^C0(),HFΘfb,) be a Hfbms where (Θfb,) is a Fbm on . If for all A,B^C0(), for each ψA and for γ>0 there exists ϱψB, satisfying FΘfb(ψ,B,γ)=Θfb(ψ,ϱψ,γ), then

    HFΘfb(A,B,γ)Θfb(ψ,ϱψ,γ).

    In this section, we develop some fixed point results by using the idea of a Hfbms. Furthermore, an example is also presented for a deeper understanding of our results.

    Recall that, given a multivalued mapping Ξ:ˆC0(), a point ψ is said to be a fixed point of Ξ if ψΞψ.

    Theorem 2.1. Let (,Θfb,) be a G-complete Fbms and (^C0(),HFΘfb,) be a Hfbms. Let Ξ:^C0() be a Mvp satisfying

    HFΘfb(Ξψ,Ξϱ,β(Θfb(ψ,ϱ,γ))γ)Θfb(ψ,ϱ,γ), (2.1)

    for all ψ,ϱ, where βFΘfb as defined in (1.1). Then Ξ has a fixed point.

    Proof. Choose {ψn} for ψ0 as follows: Let ψ1 such that ψ1Ξψ0 by the application of Lemma 1.3, we can choose ψ2Ξψ1 such that for all γ>0,

    Θfb(ψ1,ψ2,γ)HFΘfb(Ξψ0,Ξψ1,γ).

    By induction, we have ψr+1Ξψr satisfying

    Θfb(ψr,ψr+1,γ)HFΘfb(Ξψr1,Ξψr,γ)rN.

    By the application of (2.1) and Lemma 1.3, we have

    Θfb(ψr,ψr+1,γ)HFΘfb(Ξψr1,Ξψr,γ)Θfb(ψr1,ψr,γβ(Θfb(ψr1,ψr,γ)))HFΘfb(Ξψr2,Ξψr1,γβ(Θfb(ψr1,ψr,γ)))Θfb(ψr2,ψr1,γβ(Θfb(ψr1,ψr,γ))β(Θfb(ψr2,ψr1,γ)))HFΘfb(Ξψ0,Ξψ1,γβ(Θfb(ψr1,ψr,γ))β(Θfb(ψr2,ψr1,γ))β(Θfb(ψ1,ψ2,γ)))Θfb(ψ0,ψ1,γβ(Θfb(ψr1,ψr,γ))β(Θfb(ψr2,ψr1,γ))β(Θfb(ψ0,ψ1,γ))). (2.2)

    For any qN, writing q(γq)=γq+γq++γq and using [Fb4] repeatedly,

    Θfb(ψr,ψr+q,γ)Θfb(ψr,ψr+1,γqb)Θfb(ψr+1,ψr+2,γqb2)Θfb(ψr+2,ψr+3,γqb3)Θfb(ψr+q1,ψr+q,γqbq).

    Using (2.2) and [Fb5], we get

    Θfb(ψr,ψr+q,γ)Θfb(ψ0,ψ1,γqbβ(Θfb(ψr1,ψr,γ))β(Θfb(ψr2,ψr1,γ))β(Θfb(ψ0,ψ1,γ)))Θfb(ψ0,ψ1,γqb2β(Θfb(ψr,ψr+1,γ))β(Θfb(ψr1,ψr,γ))β(Θfb(ψ0,ψ1,γ)))Θfb(ψ0,ψ1,γqb3β(Θfb(ψr+1,ψr+2,γ))β(Θfb(ψr,ψr+1,γ))β(Θfb(ψ0,ψ1,γ)))Θfb(ψ0,ψ1,γqbqβ(Θfb(ψr+q2,ψr+q1,γ))β(Θfb(ψr+q3,ψr+q2,γ))β(Θfb(ψ0,ψ1,γ))).

    That is,

    Θfb(ψr,ψr+q,γ)Θfb(ψ0,ψ1,br1γq)Θfb(ψ0,ψ1,br1γq)Θfb(ψ0,ψ1,br1γq)Θfb(ψ0,ψ1,br1γq).

    Taking limit as r, we get

    limnΘfb(ψr,ψr+q,γ)=111=1.

    Hence, {ψr} is G-Cauchy sequence. By the G-completeness of , there exists ϕ such that

    Θfb(ϕ,Ξϕ,γ)Θfb(ϕ,ψr+1,γ2b)Θfb(ψr+1,Ξϕ,γ2b)Θfb(ϕ,ψr+1,γ2b)HFΘfb(Ξψr,Ξϕ,γ2b)Θfb(ϕ,ψr+1,γ2b)Θfb(ψr,ϕ,γ2bβ(Θfb(ψr,ϕ,γ)))1asr.

    By Lemma 1.1, it follows that \phi \in \Xi \phi . That is, \phi is a fixed point for \Xi .

    Remark 2.1.

    (1) If we take \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k with bk < 1 , we get Theorem 3.1 of [31].

    (2) By setting \hat{C_{0}} (\mho) = \mho the mapping \Xi \colon \mho \rightarrow \hat{C_{0}} (\mho) becomes a single valued and we get Theorem 3.1 of [32]. Notice that when \Xi is a singlevalued map, \Xi\psi becomes a singleton set and the fact that \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \gamma) = \Theta_{fb}(\Xi\psi, \Xi\varrho, \gamma) indicates that the fixed point will be unique as proved in [32].

    (3) Set b = 1 and \hat{C_{0}} (\mho) = \mho and let k\in (0, 1) be such that \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k then we get the main result of [15].

    The next example illustrates Theorem 2.1.

    Example 2.1. Let \mho = \left[0, 1\right] and define a G -complete Fbms by

    \Theta_{fb}(\psi, \varrho, \gamma) = \dfrac{\gamma}{\gamma+(\psi-\varrho)^{2}} ,

    with b\geq1. For \beta\in\mathbb{F}_{b} , define a mapping \Xi \colon \mho \rightarrow \hat{C_{0}} (\mho) by

    \begin{equation*} \Xi\psi = \begin{cases}\lbrace0\rbrace &\text {if } \psi = 0, \\ \lbrace 0, \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}\psi}{2}\rbrace & \text {otherwise.} \end{cases} \\ \end{equation*}

    For \psi = \varrho ,

    \begin{align*} \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) = 1 = & \Theta_{fb}(\psi, \varrho, \gamma). \end{align*}

    If \psi\neq \varrho , then following cases arise.

    For \psi = 0 and \varrho\in(0, 1] , we have

    \begin{align*} &\quad\mathcal{H}_{F_{\Theta_{fb}}}(\Xi0, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) \\ & = \min \lbrace \ \inf\limits_{a \in \Xi0} F_{\Theta_{fb}}( a, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma), \inf\limits_{b \in \Xi\varrho} F_{\Theta_{fb}}( \Xi0, b, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)) \rbrace\\ & = \min \Bigg\lbrace \inf\limits_{a \in \Xi0} F_{\Theta_{fb}}\left( a, \left\lbrace 0, \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}\varrho}{2}\right\rbrace , \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma\right), \inf\limits_{b \in \Xi\varrho} F_{\Theta_{fb}}\left( \left\lbrace 0\right\rbrace , b, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma\right) \Bigg\rbrace \\ & = \min \Biggl \lbrace \inf \left\lbrace F_{\Theta_{fb}}\left( 0, \lbrace0, \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}\varrho}{2} \rbrace , \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma\right) \right\rbrace, \\ &\quad\quad\quad\inf \left\lbrace F_{\Theta_{fb}}\left( \lbrace 0\rbrace , 0, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma\right), F_{\Theta_{fb}}\left( \lbrace 0\rbrace , \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}\varrho}{2}, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma\right) \right\rbrace \Biggr \rbrace \\ & = \min \Biggl \lbrace \inf \left\lbrace \sup \left\lbrace F_{\Theta_{fb}}( 0, 0, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma), F_{\Theta_{fb}}( 0, \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}\varrho}{2}, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)\right\rbrace \right\rbrace, \\ &\quad\quad\quad \inf \left\lbrace F_{\Theta_{fb}}( 0, 0, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma), F_{\Theta_{fb}}( 0, \frac{\sqrt{\beta(\Theta_{fb}(\psi, \varrho, \gamma))}y}{2}, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)\right\rbrace \Biggr\rbrace\\ & = \min \Biggl \lbrace \inf \left\lbrace \sup \left\lbrace 1, \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}}\right\rbrace \right\rbrace, \inf \left\lbrace 1, \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}}\right\rbrace \Biggr\rbrace\\ & = \min \Biggl \lbrace \inf \left\lbrace 1 \right\rbrace, \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}} \Biggr\rbrace = \min \left\lbrace 1, \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}} \right\rbrace = \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}}. \end{align*}

    It follows that

    \mathcal{H}_{F_{\Theta_{fb}}}(\Xi0, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) > \Theta_{fb}(0, \varrho, \gamma) = \dfrac{\gamma}{\gamma+\varrho^{2}}.

    For \psi and \varrho\in(0, 1] , after simplification we have

    \begin{align*} \mathcal{H}_{F_{\Theta_{fb}}}(S(\psi), \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)& = \min\left\lbrace \sup\left\lbrace \dfrac{\gamma}{\gamma+\frac{\psi^{2}}{4}}, \dfrac{\gamma}{\gamma+\frac{(\psi-\varrho)^{2}}{4}}\right\rbrace , \sup\left\lbrace \dfrac{\gamma}{\gamma+\frac{\varrho^{2}}{4}}, \dfrac{\gamma}{\gamma+\frac{(\psi-\varrho)^{2}}{4}}\right\rbrace\right\rbrace \\ & \geq\dfrac{\gamma}{\gamma+\frac{(\psi-\varrho)^{2}}{4}} > \dfrac{\gamma}{\gamma+(\psi-\varrho)^{2}} = \Theta_{fb}(\psi, \varrho, \gamma). \end{align*}

    Thus, for all cases, we have

    \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) \geq \Theta_{fb}(\psi, \varrho, \gamma).

    Since all conditions of Theorem 2.1 are satisfied and 0 is a fixed point of \Xi .

    Theorem 2.2. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C_{0}} (\mho) be a Mvp satisfying

    \begin{equation} \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) \geq \min \left\lbrace \dfrac{F_{\Theta_{fb}}( \varrho, \Xi\varrho, \gamma) \left[ 1+F_{\Theta_{fb}}( \psi, \Xi\psi, \gamma) \right] }{1+\Theta_{fb}( \psi, \varrho, \gamma) }, \Theta_{fb}( \psi, \varrho, \gamma) \right\rbrace, \end{equation} (2.3)

    for all \psi, \varrho \in \mho , where \beta\in \mathbb{F}_{\Theta_{fb}} as given in (1.1). Then \Xi has a fixed point.

    Proof. Choose \lbrace \psi_{n}\rbrace for \psi_{0} \in \mho as follows: Let \psi_{1} \in \mho such that \psi_{1} \in \Xi\psi_{0} . By the application of Lemma 1.3 we can choose \psi_{2} \in \Xi \psi_{1} such that

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant\mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0.\\ \end{equation*}

    By induction, we have \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma), \quad \forall\; r\; \in\mathbb{N}. \\ \end{equation*}

    By the application of (2.3) and Lemma 1.3 we have

    \begin{align*} &\quad\Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma) \notag\\ &\geq \min \Biggl\lbrace \dfrac{F_{\Theta_{fb}}\left( \psi_{r}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \left[ 1+F_{\Theta_{fb}}\left( \psi_{r-1}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \right] }{1+\Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right)}, \notag\\ &\quad \quad\quad\Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \Biggr\rbrace \notag\\ &\geq \min \Biggl\lbrace \dfrac{\Theta_{fb}\left( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \left[ 1+\Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \right] }{1+\Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) }, \notag\\ &\quad\quad\quad\quad \Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \Biggr\rbrace, \notag\\ &\Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \min \left\lbrace \Theta_{fb}\left( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right), \Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right)\right\rbrace. \end{align*} (2.4)

    If

    \begin{align*} &\quad \min \Bigg\lbrace \Theta_{fb}\left( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right), \Theta_{fb}\left( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right) \Bigg\rbrace\\ & = \Theta_{fb}\left( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\right), \end{align*}

    then (2.4) implies

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \Theta_{fb}\Bigl( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr). \end{equation*}

    The result is obvious by Lemma 1.2.

    If

    \begin{align*} &\quad\min \Bigg\lbrace \Theta_{fb}\Bigl( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigr( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigg\rbrace \\ & = \Theta_{fb}\Bigr( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigl), \end{align*}

    then from (2.4) we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)& \geq \Theta_{fb}\Big( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Big)\\ &\geq \Theta_{fb}\Big( \psi_{r-2}, \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))}\Big) \\ & \vdots \\ &\geqslant \Theta_{fb}\Big( \psi_{0}, \psi_{1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))\ldots \beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma)}\Big). \end{align*}

    The rest of the proof can be done by proceeding same as in Theorem 2.1.

    Remark 2.2.

    (1) If we take \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k with bk < 1 , we get Theorem 3.2 of [31].

    (2) By taking b = 1 and for some 0 < k < 1 setting \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k in Theorem 2.2, we get the main result of [30].

    Theorem 2.3. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C}_{0}(\mho) be a Mvp satisfying

    \begin{align} &\quad\mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) \\ &\geq \min \left\lbrace \dfrac{F_{\Theta_{fb}}( \varrho, \Xi\varrho, \gamma) \left[ 1+F_{\Theta_{fb}}( \psi, \Xi\psi, \gamma)+F_{\Theta_{fb}}( \varrho, \Xi\psi, \gamma) \right] }{2+\Theta_{fb}( \psi, \varrho, \gamma) }, \Theta_{fb}( \psi, \varrho, \gamma) \right\rbrace \end{align} (2.5)

    for all \psi, \varrho \in \mho , where \beta\in \mathbb{F}_{\Theta_{fb}} , the class of functions defined in (1.1). Then \Xi has a fixed point.

    Proof. Choose \lbrace \psi_{n}\rbrace for \psi_{0} \in \mho as follows: Let \psi_{1} \in \mho such that \psi_{1} \in \Xi\psi_{0} . by the application of Lemma 1.3 we can choose \psi_{2} \in \Xi \psi_{1} such that

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0.\\ \end{equation*}

    By induction, we have \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma), \quad \forall\; r\; \in\mathbb{N}. \\ \end{equation*}

    By the application of (2.5) and Lemma 1.3, we have

    \begin{align} &\quad\Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma)\\ &\geq \min \Biggl\lbrace \dfrac{F_{\Theta_{fb}}( \psi_{r}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})+F_{\Theta_{fb}}( \psi_{r}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{2+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad\quad\quad \Theta_{fb}\Bigl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Biggr\rbrace \\ &\geq \min \Biggl\lbrace \dfrac{\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})+\Theta_{fb}( \psi_{r}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{2+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad\quad\quad \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Biggr\rbrace \\ &\geq \min \left\lbrace \dfrac{\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})+1 \right] }{2+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right\rbrace \\ &\geq \min \left\lbrace \dfrac{\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 2+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{2+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right\rbrace \\ &\geq \min \left\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right\rbrace. \end{align} (2.6)

    If

    \begin{align*} &\quad\min \Bigg\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Bigg\rbrace\\ & = \Theta_{fb}\Bigg( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigg), \end{align*}

    then (2.6) implies

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \Theta_{fb}\Bigl( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{equation*}

    and the proof follows by Lemma 1.2.

    If

    \begin{align*} &\quad\min \left\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right\rbrace\\ & = \Theta_{fb}\Bigl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr).\nonumber \end{align*}

    Then from (2.6) we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) &\geq \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})\\ &\geqslant \ldots \geqslant \Theta_{fb}\Biggl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))\ldots \beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma))}\Biggr). \end{align*}

    The rest of the proof is same as in Theorem 2.1.

    Remark 2.3. Theorem 3.3 of [31] becomes a special csae of the above theorem by setting \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k where k is chosen such that bk < 1 .

    Theorem 2.4. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C}_{0}(\mho) be a multivalued mapping satisfying

    \begin{align} &\quad\mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma) \\ &\geq \min \Biggl\lbrace \dfrac{F_{\Theta_{fb}}( \psi, \Xi\psi, \gamma) \left[ 1+F_{\Theta_{fb}}( \varrho, \Xi\varrho, \gamma) \right] }{1+F_{\Theta_{fb}}( \Xi\psi, \Xi\varrho, \gamma) }, \dfrac{F_{\Theta_{fb}}( \psi, \Xi\varrho, \gamma) \left[ 1+F_{\Theta_{fb}}( \psi, \Xi\psi, \gamma) \right] }{1+\Theta_{fb}( \psi, \varrho, \gamma) }, \\ &\quad\quad\quad \dfrac{F_{\Theta_{fb}}( \psi, \Xi\psi, \gamma) \left[ 2+F_{\Theta_{fb}}( \psi, \Xi\varrho, \gamma) \right] }{1+\Theta_{fb}( \psi, \Xi\varrho, \gamma)+F_{\Theta_{fb}}( \varrho, \Xi\psi, \gamma) }, \Theta_{fb}( \psi, \varrho, \gamma) \Biggr \rbrace, \end{align} (2.7)

    for all \psi, \varrho \in \mho , where \beta \in \mathbb{F}_{fb} , the class of functions defined in (1.1). Then \Xi has a fixed point.

    Proof. In the same way as Theorem 2.1, we have

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0. \end{equation*}

    By induction, we obtain \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma), \quad \forall\; n\; \in\mathbb{N}. \end{equation*}

    Now, by (2.7) together with Lemma 1.3, we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)& \geq \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma) \\ &\geq \min \Biggl\lbrace \dfrac{F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+F_{\Theta_{fb}}( \psi_{r}, S_{\psi_{r}}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+F_{\Theta_{fb}}( \Xi \psi_{r-1}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad \quad \dfrac{F_{\Theta_{fb}}( \psi_{r}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad \quad\dfrac{F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 2+F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+F_{\Theta_{fb}}( \psi_{r-1}, \Xi \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})+F_{\Theta_{fb}}( \psi_{r}, \Xi \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad \quad \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Biggr\rbrace\\ &\geq \min \Biggl\lbrace \dfrac{\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ &\quad \quad \dfrac{\Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 1+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ & \quad \quad \dfrac{\Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \left[ 2+\Theta_{fb}( \psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right] }{1+\Theta_{fb}( \psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})+\Theta_{fb}( \psi_{r}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) }, \\ & \quad\quad \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Biggr\rbrace, \\ \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geq & \min \left\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \right\rbrace.\end{align*} (2.8)

    If

    \begin{align*} &\quad\min \Bigg\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Bigg\rbrace \\ & = \Theta_{fb}\Bigr( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigl), \end{align*}

    then (2.8) implies

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \Theta_{fb}\Bigl( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr). \end{equation*}

    Then the proof follows by Lemma 1.2.

    If

    \begin{align*} &\quad\min \Bigg\lbrace \Theta_{fb}( \psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Bigg\rbrace \\ & = \Theta_{fb}\Bigl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then from (2.6) we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) &\geq \Theta_{fb}\Bigl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & \vdots\\ & \geqslant \Theta_{fb}\bigl( \psi_{0}, \psi_{1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))\ldots \beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma))}\Bigr). \end{align*}

    The rest of the proof is similar as in Theorem 2.1.

    Remark 2.4. Again by taking \beta(\Theta_{fb}(\psi, \varrho, \gamma)) = k with kb < 1 , we get Theorem 3.4 of [31].

    Theorem 2.5. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C}_{0}(\mho) be a Mvp satisfying

    \begin{align} &\quad\mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)\\ &\geq \dfrac{ \min \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \gamma). \Theta_{fb}(\psi, \varrho, \gamma) , \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma). \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\varrho, \gamma) \rbrace )}{ \max \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma), \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\varrho, \gamma)\rbrace}, \end{align} (2.9)

    for all \psi, \varrho \in \mho , where \beta \in \mathbb{F}_{fb}. Then \Xi has a fixed point.

    Proof. In the same way as Theorem 2.1, we have

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0. \end{equation*}

    By induction we have \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma), \quad \forall\; n\; \in\mathbb{N}. \\ \end{equation*}

    Now by (2.7) together with Lemma 1.3 and some obvious simplification step, we have

    \begin{align} &\quad\Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) \geq \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{r-1}, \Xi \psi_{r}, \gamma) \\ &\geq \dfrac{\min \Biggl\lbrace \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}).\Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}). \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})\Biggr \rbrace}{\max \lbrace \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}), \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \rbrace}\\ &\geq \dfrac{\Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}). \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})}{\max \lbrace \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}), \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \rbrace} \end{align} (2.10)

    If

    \begin{align*} &\quad\max \lbrace \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \rbrace \\ & = \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then (2.10) implies

    \Theta_{fb}(\psi_{r}, \psi_{r+1}, t)\geq \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)

    Then the proof follows by Lemma 1.2.

    If

    \begin{align*} &\quad\max \lbrace \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \rbrace\\ & = \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then from (2.10) we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) &\geq \Theta_{fb}\Bigr( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & \vdots\\ & \geqslant \Theta_{fb}\Bigl( \psi_{0}, \psi_{1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))\ldots \beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma))}\Bigr). \end{align*}

    The remaining proof follows in the same way as in Theorem 2.1.

    Theorem 2.6. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C}_{0}(\mho) be a Mvp satisfying

    \begin{equation} \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)\geq \Gamma_{1}(\psi, \varrho, \gamma)* \Gamma_{2}(\psi, \varrho, \gamma), \end{equation} (2.11)

    where,

    \begin{align} \left. \begin{cases} \Gamma_{1}(\psi, \varrho, \gamma)& = \min \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \gamma) , \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma), \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\varrho, \gamma), \Theta_{fb}(\psi, \varrho, \gamma) \rbrace\\ \Gamma_{2}(\psi, \varrho, \gamma)& = \max \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\varrho, \gamma) , \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \varrho, \gamma) \rbrace \end{cases} \right\}, \end{align} (2.12)

    for all \psi, \varrho \in \mho , and \beta \in \mathbb{F}_{fb}. Then \Xi has a fixed point.

    Proof. In the same way as Theorem 2.1, we have

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0.\\ \end{equation*}

    By induction we have \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{align} \mathcal{H}_{F_{\Theta_{fb}}}(\psi_{r}, \psi_{r+1}, \gamma)& = F_{\theta}(\Xi\psi_{r-1}, \Xi\psi_{r}, \gamma)\\ &\geq \Gamma_{1}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)* \Gamma_{2}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \end{align} (2.13)

    Now,

    \begin{align} &\quad\Gamma_{1}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & = \min \Biggl \lbrace \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\Xi\psi_{r-1}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r-1}, \Xi\psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \\ &\quad\quad\quad \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\Biggr \rbrace \\ & = \min \Biggl \lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \\ & \quad\quad\quad \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\Biggr \rbrace. \\&\quad\Gamma_{1}(\psi_{r-1}, \psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \\ & = \min \Biggl\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \biggr\rbrace. \end{align} (2.14)
    \begin{align} &\quad\Gamma_{2}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigl) \\ & = \max \Bigl\lbrace \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r-1}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\Xi\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\Bigr\rbrace\\ & = \max \Bigl\lbrace \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \Theta_{fb}\Bigl(\psi_{r}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigr\rbrace \\ & = \max \Bigl\lbrace \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , 1 \Bigr\rbrace. \notag \\ \\ & \ \ \ \ \ \ \ \ \ \Gamma_{2}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) = 1. \end{align} (2.15)

    Using (2.14) and (2.15) in (2.13) we have

    \begin{align} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)&\geq \min \Bigl\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigr\rbrace *1, \\ \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)&\geq \min \Bigl\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigr\rbrace. \end{align} (2.16)

    If

    \begin{align*} &\min \Bigg\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigg\rbrace \\ & = \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigl), \end{align*}

    then (2.16) implies

    \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geq \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigl)

    Then the proof follows by Lemma 1.2

    If

    \begin{align*} &\quad\min \Bigl\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigr\rbrace\\ & = \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then from (2.16), we have

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma) &\geq \Theta_{fb}\Bigl( \psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & \vdots \\ &\geqslant \Theta_{fb}\Bigl( \psi_{0}, \psi_{1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))\beta(\Theta_{fb}(\psi_{r-2}, \psi_{r-1}, \gamma))\ldots \beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma))}\Big). \end{align*}

    The remaining proof is similar as in Theorem 2.1.

    Remark 2.5. If we set \hat{C_{0}} (\mho) = \mho the map \Xi becomes a singlevalued and we get Theorem 3.11 of [32]. Again as stated in Remark 2.1, the corresponding fixed point will be unique.

    Theorem 2.7. Let (\mho, \Theta_{fb}, *) be a G -complete Fbms with b\geqslant 1 and (\hat{C_{0}} (\mho), \mathcal{H}_{F_{\Theta_{fb}}}, *) be a Hfbms. Let \Xi \colon \mho \rightarrow \hat{C}_{0}(\mho) be a Mvp satisfying

    \begin{align} \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \beta(\Theta_{fb}(\psi, \varrho, \gamma))\gamma)\geq \dfrac{\Gamma_{1}(\psi, \varrho, \gamma)* \Gamma_{2}(\psi, \varrho, \gamma)}{\Gamma_{3}(\psi, \varrho, \gamma)}, \end{align} (2.17)

    where

    \begin{align} \left. \begin{cases} \Gamma_{1}(\psi, \varrho, \gamma)& = \min \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi, \Xi\varrho, \gamma). \Theta_{fb}(\psi, \varrho, \gamma) , \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma). \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\varrho, \gamma) \rbrace\\ \Gamma_{2}(\psi, \varrho, \gamma)& = \max \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma). \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\varrho, \gamma) , \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\psi, \gamma))^{2}\rbrace\\ \Gamma_{3}(\psi, \varrho, \gamma)& = \max \lbrace \mathcal{H}_{F_{\Theta_{fb}}}(\psi, \Xi\psi, \gamma), \mathcal{H}_{F_{\Theta_{fb}}}(\varrho, \Xi\varrho, \gamma)\rbrace \end{cases} \right\}, \end{align} (2.18)

    for all \psi, \varrho \in \mho , and \beta \in \mathbb{F}_{fb}. Then \Xi has a fixed point.

    Proof. In the same way as Theorem 2.1, we have

    \begin{equation*} \Theta_{fb}(\psi_{1}, \psi_{2}, \gamma)\geqslant \mathcal{H}_{F_{\Theta_{fb}}}(\Xi \psi_{0}, \Xi \psi_{1}, \gamma), \quad \forall\; \gamma > 0. \end{equation*}

    By induction we have \psi_{r+1} \in \Xi \psi_{r} satisfying

    \begin{align} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)& = \mathcal{H}_{F_{\Theta_{fb}}}(\Xi\psi_{r-1}, \Xi\psi_{r}, \gamma)\\ &\geq \dfrac{\Gamma_{1}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})* \Gamma_{2}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})}{\Gamma_{3}(\psi, \varrho, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})}. \end{align} (2.19)
    \begin{align} &\quad\Gamma_{1}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \\ & = \min \Biggl \lbrace \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\Xi\psi_{r-1}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr).F_{\theta}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \\ &\quad\quad\quad \mathcal{H}_{F_{\Theta_{fb}}}(\psi_{r-1}, \Xi\psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}). \mathcal{H}_{F_{\Theta_{fb}}}(\psi_{r}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \Biggr \rbrace \\ & = \min \Biggl \lbrace \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}).\Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) , \\ &\quad\quad\quad\Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr). \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Biggr \rbrace \\ & = \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr).\Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr). \end{align} (2.20)

    Similarly,

    \begin{align} &\quad\Gamma_{2}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & = \max \Biggl \lbrace \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r-1}, \Xi\psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r-1}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \\ &\quad\quad\quad \Bigl(\mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r}, \Xi\psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\Bigr)^{2} \Biggr \rbrace\\ & = \max \Biggl \lbrace \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \\ &\quad\quad\quad \Bigl(\Theta_{fb}\Bigl(\psi_{r}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\Bigr)^{2} \Biggr \rbrace\\ & = \max \Biggl\lbrace \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , 1 \Biggr\rbrace. \end{align}

    It follows that

    \begin{equation} \Gamma_{2}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) = 1. \end{equation} (2.21)
    \begin{align} &\quad\Gamma_{3}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & = \max\Big\lbrace \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r-1}, \Xi\psi_{r-1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Big), \mathcal{H}_{F_{\Theta_{fb}}}\Bigl(\psi_{r}, \Xi\psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Big\rbrace \\ & = \max \Big\lbrace \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Big) \Big\rbrace. \end{align} (2.22)

    Using (2.20), (2.21) and (2.22) in (2.19), we have

    \begin{align} \Theta_{fb}(\psi_{r}, \psi_{r+1}, t)\geq \dfrac{ \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}).\Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))})}{\max \lbrace \Theta_{fb}(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}), \Theta_{fb}(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}) \rbrace}. \end{align} (2.23)

    If

    \begin{align*} &\quad\max \Bigg \lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigg\rbrace \\ & = \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then (2.23) implies

    \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geq \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr).

    It is obvious by Lemma 1.2.

    If

    \begin{align*} &\quad\max \Bigg\lbrace \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) , \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr) \Bigg\rbrace \\ & = \Theta_{fb}\Bigl(\psi_{r}, \psi_{r+1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr), \end{align*}

    then from (2.23), we have

    \begin{equation*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, \gamma)\geq \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr). \end{equation*}

    Continuing in this way, we will get

    \begin{align*} \Theta_{fb}(\psi_{r}, \psi_{r+1}, t)&\geq \Theta_{fb}\Bigl(\psi_{r-1}, \psi_{r}, \frac{\gamma}{\beta(F_{\theta}(\psi_{r-1}, \psi_{r}, \gamma))}\Bigr)\\ & \vdots\\ & \geq \Theta_{fb}\Bigl(\psi_{0}, \psi_{1}, \frac{\gamma}{\beta(\Theta_{fb}(\psi_{r-1}, \psi_{r}, \gamma)).\beta(\Theta_{fb}(\psi_{n-2}, \psi_{r-1}, \gamma))\ldots\beta(\Theta_{fb}(\psi_{0}, \psi_{1}, \gamma))}\Bigr). \end{align*}

    The rest of the proof follows in the same way as in Theorem 2.1.

    Remark 2.6. By setting \hat{C_{_0}} (\mho) = \mho , the mapping \Xi \colon \mho \rightarrow \hat{C_{_0}} (\mho) becomes a self (singlevalued) mapping and we get Theorem 3.13 of [32].

    An application of Theorem 2.1 is presented here. Recall that the space of all continuous realvalued functions on [0, 1] is denoted by C([0, 1], \mathbb{R}) . Now set \mho = C([0, 1], \mathbb{R}) and define the G -complete Fbm on \mho by

    \Theta_{fb} (\psi, \varrho, \gamma) = e^{-\dfrac{ {\sup\limits_{u \in[0, 1]}}\vert \psi(u)-\varrho(u) \vert^{2}} {\gamma}}, \quad \forall \;\; \gamma > 0 \;\; \text{and} \; \; \psi, \varrho \in \mho.

    Consider

    \begin{equation} \psi(u)\in \int_0^u G(u, v, \psi(v))dv + h(u) \quad \text{for all} \;\; u, v \in[0, 1], \quad \text{whereas}\quad h, \psi\in C([0, 1], \mathbb{R}). \end{equation} (3.1)

    Here G \colon [0, 1]\times[0, 1] \times \mathbb{R}\rightarrow P_{cv}(\mathbb{R}) is multivalued function and P_{cv}(\mathbb{R}) represents the collections of convex and compact subsets of \mathbb{R} . Moreover, for each \psi in C([0, 1], \mathbb{R}) the operator G(\cdot, \cdot, \psi) is lower semi-continuous.

    For the integral inclusion given in (3.1), define a multivalued operator S: \mho\rightarrow \hat{C_{0}} (\mho) by

    S\psi(u) = \Biggl\lbrace w \in \mho : w \in \int_0^u G(u, v, \psi(v))dv + h(u), \quad u \in [0, 1]\Biggr\rbrace.

    Now for arbitrary \psi \in (C([0, 1], \mathbb{R}) , denote G_\psi(u, v) = G(u, v, \psi(v)) where u, v\in [0, 1] . For the multivalued map G_\psi : [0, 1]\times [0, 1]\rightarrow P_{cv}(\mathbb{R}) , by Michael selection theorem [34], there exists a continuous selection g_\psi :[0, 1] \times [0, 1]\rightarrow \mathbb{R} such that g_\psi(u, v)\in G_\psi(u, v) for each u, v\in [0, 1] . It follows that

    \int_0^u g_\psi(u, v)dv + h(u) \in S\psi(u).

    Since g_\psi is continuous on [0, 1]\times [0, 1] and h is continuous on [0, 1] , therefore both g_\psi and h are bounded realvalued functions. It follows that, the operator S\psi is nonempty and S\psi \in \hat{C_{0}} (\mho) .

    With the above setting, the upcoming outcome shows the existence of a solution of the integral inclusion (3.1).

    Theorem 3.1. Let \mho = C([0, 1], \mathbb{R}) and define the multivalued operator S: \mho \rightarrow \hat{C_{0}} (\mho) by

    S\psi(u) = \Biggl\lbrace w \in \mho : w \in \int_0^u G(u, v, \psi(v))dv + h(u), \quad u \in [0, 1]\Biggr\rbrace,

    where h:[0, 1]\rightarrow \mathbb{R} is continuous and the map G:[0, 1]\times [0, 1]\times \mathbb{R}\rightarrow P_{cv}(\mathbb{R}) is defined in such a way that for every \psi\in C([0, 1], \mathbb{R}) , the operator G(\cdot, \cdot, \psi) is lower semi-continuous. Assume further that the given terms are satisfied:

    (i) There exists a continuous mapping f \colon [0, 1]\times [0, 1]\rightarrow [0, \infty) such that

    \mathcal{H}_{F_{\Theta_{fb}}}( G(u, v, \psi(v))-G(u, v, \varrho(v))\leq f^{2}(u, v)\vert \psi(v)-\varrho(v)\vert^{2},

    for each \psi, \varrho \in \mho and u, v\in [0, 1] .

    (ii) There exists \beta \in \mathbb{F}_{\Theta 2} , such that

    { \sup\limits_{u \in[0, 1]}}\int_0^u f^{2}(u, v)dv \leq \beta({\Theta_{fb}}(\psi, \varrho, \gamma)) .

    Then (3.1) has a solution in \mho .

    Proof. We will show that the operator S satisfies the conditions of Theorem 2.1. In particular we prove (2.1) as follows:

    Let \psi, \varrho \in \mho be such that q\in S\psi . As stated earlier, by selection theorem there is g_\psi(u, v)\in G_\psi(u, v) = G(u, v, \psi(v)) for u, v \in [0, 1] such that

    q(u) = \int_0^u g_\psi(u, v)dv+h(u), \quad u\in [0, 1].

    Further, the condition (ⅰ) ensures that there is some g(u, v)\in G_\varrho(u, v) such that

    \vert g_\psi(u, v)-g(u, v)\le f^{2}(u, v)\vert \psi(v)-\varrho(v)\vert^{2}, \quad\forall\, u, v\in [0, 1].

    Now consider the multivalued operator T defined as follows:

    T(u, v) = G_\varrho(u, v)\cap \left\lbrace w\in \mathbb{R} : \left\vert g_\psi(u, v)-w\right\vert\le f^{2}(u, v)\vert \psi(v)-\varrho(v)\vert^{2}\right\rbrace.

    Since, by construction, T is lower semi-continuous, it follows again by the selection theorem that there is continuous function g_\varrho(u, v):[0, 1]\times [0, 1]\rightarrow \mathbb{R} such that for each u, v \in [0, 1] , g_\varrho(u, v) \in T(u, v) .

    Thus, we have

    r(u) = \int_0^u g_\varrho(u, v)dv+h(u)\, \in \int_0^u G(u, v, \varrho(v))dv+h(u), \quad u\in [0, 1].

    Therefore, for each u\in [0, 1] we get

    \begin{align*} e^{-\dfrac{ {\sup\limits_{t \in[0, 1]}}\vert q(u)- r(u)) \vert^{2}}{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma}}& \geq e^{-\dfrac{ {\sup\limits_{u \in[0, 1]}}\int_0^u \vert g_{\psi}(u, v)-g_{\varrho}(u, v) \vert^{2} dv}{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma}}\\ & \geq e^{-\dfrac{ {\sup\limits_{u \in[0, 1]}}\int_0^u f^{2}(u, v) \vert \psi(v)-\varrho(v) \vert^{2} dv}{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma}}\\ & \geq e^{-\dfrac{\vert \psi(v)-\varrho(v) \vert^{2} {\sup\limits_{u \in[0, 1]}}\int_0^u f^{2}(u, v) dv}{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma}}\\ & \geq e^{-\dfrac{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\vert \psi(v)-\varrho(v) \vert^{2}}{\beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma}}\\ & = e^{-\dfrac{\vert \psi(v)-\varrho(v) \vert^{2}}{\gamma}}\\ & \geq e^{-\dfrac{ {\sup\limits_{v \in[0, 1]}}\vert \psi(v)-\varrho(v) \vert^{2}}{\gamma}}\\ & = \Theta_{fb}(\psi, \varrho, \gamma). \end{align*}

    This implies that,

    \Theta_{fb}(q, r, \beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma)\geq \Theta_{fb}(\psi, \varrho, \gamma).

    Interchanging the roles of \psi and \varrho , we get

    \mathcal{H}_{F_{\Theta_{fb}}}(S\psi, S\varrho, \beta({\Theta_{fb}}(\psi, \varrho, \gamma))\gamma) \geq \Theta_{fb}( \psi, \varrho, \gamma).

    Hence, by Theorem 2.1, the operator S has a fixed point which in turn proves the existence of a solution of integral inclusion (3.1).

    In the present work, in the setting of a Hausdorff Fbms, some fixed fixed point results for multivalued mappings are established. The main result, that is, Theorem 2.1 shows that a multivalued mapping satisfying Geraghty type contractions on G -complete Hfbms has a fixed point. Example 2.1 illustrates the main result. Some other interesting fixed point theorems are also proved for the multivalued mappings satisfying certain contraction condition on G -complete Hfbms. The results proved in [30,31,32] turn out to be special cases of the results established in this work. For the significance of our results, an application is presented to prove the existence of solution of an integral inclusion.

    The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work grant code: 22UQU4331214DSR02

    The authors declare that they have no conflict of interest.

    [1] W. Boothby, An Introduction to Differentiable Manifolds and Riemannian Geometry, Academic Press, NY, 1975.
    [2] P. Bracken, Integrability and Prolongation Structure for a Generalized Korteweg-de Vries Equation, Pacific J. Math., 2, (2009), 293-302.
    [3] P. Bracken, A Geometric Interpretation of Prolongation by Means of Connections, J. Math. Phys., 51, (2010), 113502.
    [4] P. Bracken, Geometric Approaches to Produce Prolongations for Nonlinear Partial Differential Equations, Int. J. Geom. Methods M., 10, (2013), 1350002.
    [5] P. Bracken, An Exterior Differential System for a Generalized Korteweg-de Vries Equation and its Associated Integrability, Acta Appl. Math., 95, (2007), 223-231.
    [6] S. S. Chern, W. H. Chen and K. S. Lam, Lectures on Differential Geometry, World Scientific, Singpore, 1999.
    [7] C. S. Gardner, J. M. Greene, M. D. Kruskal and R. M. Muira, A method for solving the Korteweg-de Vries equation, Phys. Rev. Lett., 19, (1967), 1095-1097.
    [8] P. D. Lax, Integrals of Nonlinear Equations of Evolution and Solitary Waves, Commun. Pur. Appl. Math., 21 (1968), 467-490.
    [9] J. M. Lee, Manifolds and Differential Geometry, AMS Graduate Studies in Mathematics, vol. 107, Providence, RI, 2009.
    [10] C.-Q. Su, Y. Tian Gao, X. Yu, L. Xue and Yu-Jia Shen, Exterior differential expression of the (1+1)-dimensional nonlinear evolution equation with Lax integrability, J. Math. Anal. Appl., 435, (2016), 735-745.
    [11] H. D. Wahlquist and F. B. Estabrook, Bäcklund Transformation for Solutions of the Korteweg-de Vries Equation, Phys. Rev. Lett., 31 (1973), 1386-1390.
    [12] H. D. Wahlquist and F. B. Estabrook, Prolongation structures of nonlinear evolution equations, J. Math. Phys., 16, (1975), 1-7.
    [13] H. D. Wahlquist and F. B. Estabrook, Prolongation structures of nonlinear evolution equations, J. Math. Phys., 17, (1976), 1293-1297.
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