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Research Article Fixed Point Results Satisfying Rational Type Contraction in -Metric Spaces Branislav Z. PopoviT, 1 Muhammad Shoaib, 2 and Muhammad Sarwar 2 1 Faculty of Science, University of Kragujevac, Radoja DomanoviΒ΄ ca 12, 34000 Kragujevac, Serbia 2 Department of Mathematics, University of Malakand, Chakdara, Lower Dir 18800, Pakistan Correspondence should be addressed to Branislav Z. PopoviΒ΄ c; [email protected] Received 15 May 2016; Accepted 6 June 2016 Academic Editor: Filomena Cianciaruso Copyright Β© 2016 Branislav Z. PopoviΒ΄ c et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A unique fixed point theorem for three self-maps under rational type contractive condition is established. In addition, a unique fixed point result for six continuous self-mappings through rational type expression is also discussed. 1. Introduction Fixed point theory is one of the core subjects of nonlinear analysis. is theory is not constrained to mathematics; it is also applicable to other disciplines. It is closely linked with social and medical science, military applications, graph the- ory [1], game theory, economics [2], statistics, and medicine. is theory is divided into three categories: topological fixed point theory, metric fixed point theory, and discrete fixed point theory. In metric fixed point theory, the first result proved by Banach [3] is known as Banach contraction principle. Many researchers extended this principle for the study of fixed points and common fixed points using different types of contraction such as weak contraction [4, 5], integral type contraction [6], rational type contraction [7], and T-Hardy Rogers type contraction [8]. For more details, see [9–11] and so forth. Dass and Gupta [12] gave the extension of Banach’s contraction mapping principle by using a contractive con- dition of rational type. Jaggi [7] proved some unique fixed point results through contractive condition of rational type in metric spaces. Harjani et al. [13] studied the results of Jaggi in the setting of partially ordered metric spaces. Using generalized weak contractions Luong and uan [14] gener- alized the results of [13] through rational type expressions in the context of partially ordered metric spaces. Chandok and Karapinar [15] generalized the results of Harjani and established common fixed point results for weak contractive conditions satisfying rational type expressions in partially ordered metric spaces. Mustafa et al. [16] discussed fixed point results by almost generalized contraction via rational type expression which generalizes, extends, and unifies the results of Jaggi [7], Harjani et al. [13], and Luong and uan [14], respectively. Fixed point theorems for contractive type conditions satisfying rational inequalities in metric spaces have been developed in a number of works; see [17–20] and so forth. Mustafa and Sims [21] generalized the notion of metric space as an appropriate notion of generalized metric space called -metric space. ey have investigated convergence in -metric spaces, introduced completeness of -metric spaces, and proved a Banach contraction mapping theorem and some other fixed point theorems involving contractive type mappings in -metric spaces using different contractive conditions. Later, various authors have proved some common fixed point theorems in these spaces (see [8, 22–24]). Sanodia et al. [25] used rational type contraction and investigated a unique fixed point theorem for single mapping in -metric spaces. Gandhi and Bajpai [26] generalized the result of Sanodia et al. and proved unique common fixed point results for three mappings in -metric space satisfying Hindawi Publishing Corporation Journal of Function Spaces Volume 2016, Article ID 9536765, 7 pages http://dx.doi.org/10.1155/2016/9536765
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Page 1: Research Article Fixed Point Results Satisfying Rational ...downloads.hindawi.com/journals/jfs/2016/9536765.pdfpoint theory, metric xed point theory, and discrete x ed pointtheory.

Research ArticleFixed Point Results Satisfying Rational TypeContraction in 𝐺-Metric Spaces

Branislav Z. PopoviT,1 Muhammad Shoaib,2 and Muhammad Sarwar2

1Faculty of Science, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia2Department of Mathematics, University of Malakand, Chakdara, Lower Dir 18800, Pakistan

Correspondence should be addressed to Branislav Z. Popovic; [email protected]

Received 15 May 2016; Accepted 6 June 2016

Academic Editor: Filomena Cianciaruso

Copyright Β© 2016 Branislav Z. Popovic et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

A unique fixed point theorem for three self-maps under rational type contractive condition is established. In addition, a uniquefixed point result for six continuous self-mappings through rational type expression is also discussed.

1. Introduction

Fixed point theory is one of the core subjects of nonlinearanalysis. This theory is not constrained to mathematics; it isalso applicable to other disciplines. It is closely linked withsocial and medical science, military applications, graph the-ory [1], game theory, economics [2], statistics, and medicine.This theory is divided into three categories: topological fixedpoint theory, metric fixed point theory, and discrete fixedpoint theory.

In metric fixed point theory, the first result proved byBanach [3] is known as Banach contraction principle. Manyresearchers extended this principle for the study of fixedpoints and common fixed points using different types ofcontraction such as weak contraction [4, 5], integral typecontraction [6], rational type contraction [7], and T-HardyRogers type contraction [8]. For more details, see [9–11] andso forth.

Dass and Gupta [12] gave the extension of Banach’scontraction mapping principle by using a contractive con-dition of rational type. Jaggi [7] proved some unique fixedpoint results through contractive condition of rational typein metric spaces. Harjani et al. [13] studied the results ofJaggi in the setting of partially ordered metric spaces. Usinggeneralized weak contractions Luong and Thuan [14] gener-alized the results of [13] through rational type expressions

in the context of partially ordered metric spaces. Chandokand Karapinar [15] generalized the results of Harjani andestablished common fixed point results for weak contractiveconditions satisfying rational type expressions in partiallyordered metric spaces. Mustafa et al. [16] discussed fixedpoint results by almost generalized contraction via rationaltype expression which generalizes, extends, and unifies theresults of Jaggi [7], Harjani et al. [13], and Luong and Thuan[14], respectively. Fixed point theorems for contractive typeconditions satisfying rational inequalities in metric spaceshave been developed in a number of works; see [17–20] andso forth.

Mustafa and Sims [21] generalized the notion of metricspace as an appropriate notion of generalized metric spacecalled 𝐺-metric space. They have investigated convergencein 𝐺-metric spaces, introduced completeness of 𝐺-metricspaces, and proved a Banach contraction mapping theoremand some other fixed point theorems involving contractivetype mappings in 𝐺-metric spaces using different contractiveconditions. Later, various authors have proved some commonfixed point theorems in these spaces (see [8, 22–24]).

Sanodia et al. [25] used rational type contraction andinvestigated a unique fixed point theorem for single mappingin 𝐺-metric spaces. Gandhi and Bajpai [26] generalized theresult of Sanodia et al. and proved unique common fixedpoint results for three mappings in 𝐺-metric space satisfying

Hindawi Publishing CorporationJournal of Function SpacesVolume 2016, Article ID 9536765, 7 pageshttp://dx.doi.org/10.1155/2016/9536765

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2 Journal of Function Spaces

rational type contractive condition. Recently, Shrivastava etal. [27] established some unique fixed point theorem for somenew rational type contraction.

The aim of this paper is to establish two common fixedpoint theorems satisfying rational type contraction. In thefirst result, we discuss the existence and uniqueness ofcommon fixed point for three self-maps in the context of𝐺-metric space, while in the second one we studied theuniqueness of common fixed point for six continuous self-mappings in the setting of 𝐺-metric through rational typeexpression.

2. Preliminaries

We recall some definitions that will be used in our discussion.

Definition 1 (see [21]). Let𝑋 be a nonempty set and let𝐺 : 𝑋×

𝑋×𝑋 β†’ R+ be a function satisfying the following conditions:

(1) 𝐺(π‘₯, 𝑦, 𝑧) = 0 implies that π‘₯ = 𝑦 = 𝑧 for all π‘₯, 𝑦, 𝑧 ∈

𝑋.

(2) 𝐺(π‘₯, π‘₯, 𝑦) ≀ 𝐺(π‘₯, 𝑦, 𝑧) for all π‘₯, 𝑦, 𝑧 ∈ 𝑋.

(3) 𝐺(π‘₯, 𝑦, 𝑧) = 𝐺(π‘₯, 𝑧, 𝑦) = 𝐺(𝑦, 𝑧, π‘₯) β‹… β‹… β‹… for all π‘₯, 𝑦, 𝑧 ∈

𝑋.

(4) 𝐺(π‘₯, 𝑦, 𝑧) ≀ 𝐺(π‘₯, π‘Ž, π‘Ž)+𝐺(π‘Ž, 𝑦, 𝑧) for allπ‘₯, 𝑦, 𝑧, π‘Ž ∈ 𝑋.

Then, it is called 𝐺-metric and the pair (𝑋, 𝐺) is a 𝐺-metric space.

Proposition 2 (see [21]). Let (𝑋, 𝐺) be a 𝐺-metric space. Thefollowing are equivalent:

(1) (π‘₯𝑛) is 𝐺-convergent to π‘₯.

(2) 𝐺(π‘₯𝑛, π‘₯𝑛, π‘₯) β†’ 0 as 𝑛 β†’ ∞.

(3) 𝐺(π‘₯𝑛, π‘₯, π‘₯) β†’ 0 as 𝑛 β†’ ∞.

(4) 𝐺(π‘₯𝑛, π‘₯π‘š, π‘₯) β†’ 0 as 𝑛,π‘š β†’ ∞.

Definition 3 (see [22, 28]). A pair of self-mappings 𝑓, 𝑔 in a𝐺-metric space is said to be weakly commuting if

𝐺 (𝑓𝑔π‘₯, 𝑔𝑓π‘₯, 𝑔𝑓π‘₯) ≀ 𝐺 (𝑓π‘₯, 𝑔π‘₯, 𝑔π‘₯) , βˆ€π‘₯ ∈ 𝑋. (1)

Sanodia et al. [25] proved the following fixed point theoremin the setting of 𝐺-metric space.

Theorem4. Let (𝑋, 𝐺) be a𝐺-complete𝐺-metric space and let𝑓 : 𝑋 β†’ 𝑋 be a self-map satisfying the condition

𝐺 (𝑓π‘₯, 𝑓𝑦, 𝑓𝑧) ≀ 𝐴

β‹…

max {𝐺2(π‘₯, 𝑓π‘₯, 𝑓𝑦) , 𝐺

2(𝑦, 𝑓𝑦, 𝑓𝑧) , 𝐺

2(𝑧, 𝑓𝑧, 𝑓π‘₯)}

𝐺 (π‘₯, 𝑦, 𝑧)

(2)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with 0 ≀ 𝐴 < 1. Then, 𝑓 has a uniquecommon fixed point in 𝑋.

Theorem 5. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑆, 𝑇 : 𝑋 β†’ 𝑋 be two self-maps such that 𝑆(𝑋) βŠ‚ 𝑇(𝑋)

satisfying the following condition:

𝐺 (𝑇π‘₯, 𝑇𝑦, 𝑇𝑧) ≀ 𝐴

β‹…

max {𝐺2(𝑆π‘₯, 𝑇π‘₯, 𝑇𝑦) , 𝐺

2(𝑆𝑦, 𝑇𝑦, 𝑇𝑧) , 𝐺

2

(𝑆𝑧, 𝑇𝑧, 𝑇π‘₯)}

𝐺 (𝑆π‘₯, 𝑆𝑦, 𝑆𝑧)

(3)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋with 0 ≀ 𝐴 < 1.Then, 𝑆 and𝑇 have a uniquecommon fixed point in 𝑋.

Gandhi and Bajpai [26] proved unique common fixedpoint results satisfying the following rational type contractivecondition.

Theorem6. Let (𝑋, 𝐺) be a𝐺-complete𝐺-metric space and let𝑓, 𝑔, β„Ž : 𝑋 β†’ 𝑋 be three self-mappings satisfying the condition

𝐺 (𝑓π‘₯, 𝑔𝑦, β„Žπ‘§) ≀ 𝐴

β‹…

max {𝐺2(π‘₯, 𝑓π‘₯, 𝑔𝑦) , 𝐺

2(𝑦, 𝑔𝑦, β„Žπ‘§) , 𝐺

2(𝑧, β„Žπ‘§, 𝑓π‘₯)}

𝐺 (π‘₯, 𝑦, 𝑧)

(4)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with 0 ≀ 𝐴 < 1. Then, 𝑓, 𝑔, and β„Ž have aunique common fixed point in 𝑋.

Currently, Shrivastava et al. [27] studied the followingresult.

Theorem7. Let (𝑋, 𝐺) be a𝐺-complete𝐺-metric space and let𝑓 : 𝑋 β†’ 𝑋 be a self-map satisfying the condition

𝐺 (𝑓π‘₯, 𝑓𝑦, 𝑓𝑧) ≀ 𝐴 ⋅𝐺 (π‘₯, 𝑓𝑦, 𝑓𝑦) + 𝐺 (π‘₯, 𝑓𝑧, 𝑓𝑧)

2+ 𝐡

β‹… (𝐺 (π‘₯, 𝑓𝑦, 𝑓𝑦)𝐺 (π‘₯, 𝑓𝑦, 𝑓𝑦) + 𝐺 (π‘₯, 𝑓𝑧, 𝑓𝑧)

+ 𝐺 (𝑦, 𝑓π‘₯, 𝑓π‘₯) + 𝐺 (𝑧, 𝑓π‘₯, 𝑓π‘₯))

β‹… (2 (𝐺 (π‘₯, 𝑓𝑦, 𝑓𝑦) + 𝐺 (𝑦, 𝑓π‘₯, 𝑓π‘₯)))βˆ’1

(5)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with 0 ≀ 𝐴 + 𝐡 < 1/2. Then, 𝑓 has a uniquecommon fixed point in 𝑋 and 𝑓 is 𝐺-continuous at 𝑒.

3. Main Results

Our first new result is the following.

Theorem8. Let (𝑋, 𝐺) be a𝐺-complete𝐺-metric space and let𝑆, 𝑇, 𝑅 : 𝑋 β†’ 𝑋 be three self-mappings satisfying the followingcondition:

𝐺 (𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) ≀ 𝐴 β‹… (𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (𝑦, 𝑇𝑦, 𝑅𝑧)

+ [𝐺 (π‘₯, 𝑦, 𝑧)]2

+ 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑦, 𝑧))

β‹… (𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺 (π‘₯, 𝑦, 𝑧) + 𝐺 (𝑦, 𝑇𝑦, 𝑅𝑧))βˆ’1

+ 𝐡 β‹… (𝐺 (𝑦, 𝑇𝑦, 𝑅𝑧) [1 + 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)]

β‹… (1 + 𝐺 (π‘₯, 𝑦, 𝑧))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯, 𝑦, 𝑧)

(6)

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Journal of Function Spaces 3

for allπ‘₯, 𝑦, 𝑧 ∈ 𝑋withπ‘₯ = 𝑦 = 𝑧 = π‘₯,𝐴, 𝐡, 𝐢 β‰₯ 0with 0 ≀ 𝐴+

𝐡+𝐢 < 1,𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦)+𝐺(π‘₯, 𝑦, 𝑧)+𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0.Then, 𝑆,𝑇, and 𝑅 have a common fixed point. Further, if𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦)+

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0 implies 𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) = 0, then𝑆, 𝑇, and 𝑅 have a unique common fixed point in 𝑋.

Proof. Let π‘₯0be arbitrary in 𝑋; we define a sequence π‘₯

𝑛by

the following rules:

π‘₯3𝑛+1

= 𝑆π‘₯3𝑛

,

π‘₯3𝑛+2

= 𝑇π‘₯3𝑛+1

,

π‘₯3𝑛+3

= 𝑅π‘₯3𝑛+2

,

βˆ€π‘› ∈ X.

(7)

Now, we have to show that π‘₯𝑛is a 𝐺-Cauchy sequence in 𝑋.

Consider 𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0; from(6), we have

𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) = 𝐺 (𝑆π‘₯3𝑛

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

) ≀ 𝐴

β‹… [𝐺 (π‘₯3𝑛

, 𝑆π‘₯3𝑛

, 𝑇π‘₯3𝑛+1

) 𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

)

+ [𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]2

+ 𝐺 (π‘₯3𝑛

, 𝑆π‘₯3𝑛

, 𝑇π‘₯3𝑛+1

)

β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)] (𝐺 (π‘₯3𝑛

, 𝑆π‘₯3𝑛

, 𝑇π‘₯3𝑛+1

)

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

+ 𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

))βˆ’1

+ 𝐡

β‹… (𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

) [1

+ 𝐺 (π‘₯3𝑛

, 𝑆π‘₯3𝑛

, 𝑇π‘₯3𝑛+1

)] (1

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

= 𝐴 β‹… [𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

)

+ [𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]2

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)] (𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) + 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

))βˆ’1

+ 𝐡 β‹… (𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) [1

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)] (1

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

= 𝐴 β‹… [𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) (𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

)

+ 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) + 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

))]

β‹… (𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) + 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

+ 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

))βˆ’1

+ 𝐡

β‹… (𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) [1 + 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]

β‹… (1 + 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

,

π‘₯3𝑛+2

) = 𝐴 β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) + 𝐡 β‹… 𝐺 (π‘₯3𝑛+1

,

π‘₯3𝑛+2

, π‘₯3𝑛+3

) + 𝐢 β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) = (𝐴 + 𝐢)

β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) + 𝐡 β‹… 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) ,

(8)

which implies that

𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) ≀ β„Ž β‹… 𝐺 (π‘₯3𝑛

, π‘₯3𝑛+1

, π‘₯3𝑛+2

) , (9)

where β„Ž = (𝐴 + 𝐢)/(1 βˆ’ 𝐡).Similarly,

𝐺 (π‘₯3𝑛+3

, π‘₯3𝑛+4

, π‘₯3𝑛+5

) ≀ β„Ž β‹… 𝐺 (π‘₯3𝑛+2

, π‘₯3𝑛+3

, π‘₯3𝑛+4

) . (10)

Therefore, for all 𝑛, we have

𝐺 (π‘₯𝑛+1

, π‘₯𝑛+2

, π‘₯𝑛+3

) ≀ β„Ž β‹… 𝐺 (π‘₯𝑛, π‘₯𝑛+1

, π‘₯𝑛+2

) ≀ β‹… β‹… β‹…

≀ β„Žπ‘›+1

β‹… 𝐺 (π‘₯0, π‘₯1, π‘₯2) .

(11)

Now, for all 𝑙, π‘š, 𝑛, with 𝑙 > π‘š > 𝑛, using rectangularinequality, the second axiom of the 𝐺-metric, and (11), wehave

𝐺 (π‘₯𝑛, π‘₯π‘š, π‘₯𝑙) ≀ 𝐺 (π‘₯

𝑛, π‘₯𝑛+1

, π‘₯𝑛+1

)

+ 𝐺 (π‘₯𝑛+1

, π‘₯𝑛+2

, π‘₯𝑛+2

) + β‹… β‹… β‹…

+ 𝐺 (π‘₯π‘™βˆ’2

, π‘₯π‘™βˆ’1

, π‘₯𝑙)

≀ 𝐺 (π‘₯𝑛, π‘₯𝑛+1

, π‘₯𝑛+2

)

+ 𝐺 (π‘₯𝑛+1

, π‘₯𝑛+2

, π‘₯𝑛+3

) + β‹… β‹… β‹…

+ 𝐺 (π‘₯π‘™βˆ’2

, π‘₯π‘™βˆ’1

, π‘₯𝑙)

≀ β„Žπ‘›

+ β„Žπ‘›+1

+ β‹… β‹… β‹… + β„Žπ‘™βˆ’2

β‹… 𝐺 (π‘₯0, π‘₯1, π‘₯2)

=β„Žπ‘›

1 βˆ’ β„Žβ‹… 𝐺 (π‘₯

0, π‘₯1, π‘₯2) ,

(12)

where 𝐺(π‘₯𝑛, π‘₯π‘š, π‘₯𝑙) β†’ 0 as 𝑛,π‘š, 𝑙 β†’ ∞.

This shows that π‘₯𝑛is a 𝐺-Cauchy sequence. But (𝑋, 𝐺) is

𝐺-complete 𝐺-metric space so there exists 𝑀 in 𝑋 such thatπ‘₯𝑛→ 𝑀 as 𝑛 tends to infinity.Now, we assume that 𝑠𝑀 = 𝑀. Using condition (6), we

have

𝐺 (𝑆𝑀, π‘₯3𝑛+2

, π‘₯3𝑛+3

) = 𝐺 (𝑆𝑀, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

) ≀ 𝐴

β‹… [𝐺 (𝑀, 𝑆𝑀, 𝑇π‘₯3𝑛+1

) 𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

)

+ [𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]2

+ 𝐺 (𝑀, 𝑆𝑀, 𝑇π‘₯3𝑛+1

)

β‹… 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)] (𝐺 (𝑀, 𝑆𝑀, 𝑇π‘₯3𝑛+1

)

+ 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

+ 𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

))βˆ’1

+ 𝐡

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4 Journal of Function Spaces

β‹… (𝐺 (π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+1

, 𝑅π‘₯3𝑛+2

)

β‹… [1 + 𝐺 (𝑀, 𝑆𝑀, 𝑇π‘₯3𝑛+1

)]

β‹… (1 + 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

))βˆ’1

) + 𝐢

β‹… 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

) = 𝐴 β‹… [𝐺 (𝑀, 𝑆𝑀, π‘₯3𝑛+2

)

β‹… 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) + [𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]2

+ 𝐺 (𝑀, 𝑆𝑀, π‘₯3𝑛+2

) 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)]

β‹… (𝐺 (𝑀, 𝑠𝑀, π‘₯3𝑛+2

) + 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

)

+ 𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

))βˆ’1

+ 𝐡

β‹… (𝐺 (π‘₯3𝑛+1

, π‘₯3𝑛+2

, π‘₯3𝑛+3

) [1 + 𝐺 (𝑀, 𝑆𝑀, π‘₯3𝑛+2

)]

β‹… (1 + 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

))βˆ’1

) + 𝐢

β‹… 𝐺 (𝑀, π‘₯3𝑛+1

, π‘₯3𝑛+2

) .

(13)

As π‘₯𝑛is 𝐺-Cauchy sequence and converges to 𝑀, therefore,

by taking limit 𝑛 β†’ ∞, we get 𝐺(𝑆𝑀,𝑀, 𝑀) ≀ 0 which is heldonly if 𝐺(𝑆𝑀,𝑀, 𝑀) = 0 implies that 𝑆𝑀 = 𝑀. Similarly, it canbe shown that 𝑇𝑀 = 𝑀 and 𝑅𝑀 = 𝑀. Hence, 𝑀 is a commonfixed point of 𝑆, 𝑇 and 𝑅.

Uniqueness. Suppose that 𝑆, 𝑇, and 𝑅 have two common fixedpoints 𝑧 and𝑀 such that 𝑧 = 𝑀. Since condition𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦)+

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0 implies 𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) = 0, wehave that𝐺(𝑧, 𝑆𝑧, 𝑇𝑀)+𝐺(𝑧, 𝑀, 𝑀)+𝐺(𝑧, 𝑇𝑀, 𝑅𝑀) = 0 implies𝐺(𝑆𝑧, 𝑇𝑀, 𝑅𝑀) = 0. Therefore, one can get the following:

𝐺 (𝑆𝑧, 𝑇𝑀, 𝑅𝑀) = 𝐺 (𝑧, 𝑀, 𝑀) = 0

implies that 𝑧 = 𝑀,

(14)

which is a contradiction. Therefore, the common fixed pointis unique.

Corollary 9. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑆, 𝑇, 𝑅 : 𝑋 β†’ 𝑋 be three self-mappings satisfying thecondition

𝐺 (𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) ≀ 𝐴 β‹… [𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑇𝑦, 𝑅𝑧)

+ [𝐺 (π‘₯, 𝑦, 𝑧)]2

+ 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑦, 𝑧)]

β‹… (𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺 (π‘₯, 𝑦, 𝑧) + 𝐺 (π‘₯, 𝑇𝑦, 𝑅𝑧))βˆ’1

(15)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴 β‰₯ 0 with 0 ≀ 𝐴 <

1, 𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0. Then, 𝑆, 𝑇,and 𝑅 have a common fixed point. Further, if 𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦) +

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0 implies 𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) = 0, then𝑆, T, and 𝑅 have a unique common fixed point in 𝑋.

Proof. The proof follows by taking 𝐡 = 𝐢 = 0 in Theorem 8.

Corollary 10. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑆, 𝑇, 𝑅 : 𝑋 β†’ 𝑋 be three self-mappings satisfying thecondition

𝐺 (𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) ≀ 𝐡

⋅𝐺 (𝑦, 𝑇𝑦, 𝑅𝑧) [1 + 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)]

1 + 𝐺 (π‘₯, 𝑦, 𝑧)

+ 𝐢 β‹… 𝐺 (π‘₯, 𝑦, 𝑧)

(16)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐡, 𝐢 β‰₯ 0 with 0 ≀

𝐡+𝐢 < 1,𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦)+𝐺(π‘₯, 𝑦, 𝑧)+𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0.Then 𝑆,𝑇, and 𝑅 have a common fixed point. Further, if𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦)+

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑅𝑧) = 0 implies 𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) = 0, then𝑆, 𝑇, and 𝑅 have a unique common fixed point in 𝑋.

Proof. The proof follows by taking 𝐴 = 0 in Theorem 8.

Corollary 11. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑆, 𝑇 : 𝑋 β†’ 𝑋 be two self-mappings satisfying the condition

𝐺 (𝑆π‘₯, 𝑇𝑦, 𝑇𝑧) ≀ 𝐴 β‹… [𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑇𝑦, 𝑇𝑧)

+ [𝐺 (π‘₯, 𝑦, 𝑧)]2

+ 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑦, 𝑧)]

β‹… (𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺 (π‘₯, 𝑦, 𝑧) + 𝐺 (π‘₯, 𝑇𝑦, 𝑇𝑧))βˆ’1

+ 𝐡 β‹… (𝐺 (𝑦, 𝑇𝑦, 𝑇𝑧) [1 + 𝐺 (π‘₯, 𝑆π‘₯, 𝑇𝑦)]

β‹… (1 + 𝐺 (π‘₯, 𝑦, 𝑧))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯, 𝑦, 𝑧)

(17)

for allπ‘₯, 𝑦, 𝑧 ∈ 𝑋withπ‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴, 𝐡, 𝐢 β‰₯ 0with 0 ≀ 𝐴+

𝐡 +𝐢 < 1, 𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦) + 𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑇𝑧) = 0. Then,𝑆 and 𝑇 have a common fixed point. Further, if 𝐺(π‘₯, 𝑆π‘₯, 𝑇𝑦) +

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑇𝑧) = 0 implies 𝐺(𝑆π‘₯, 𝑇𝑦, 𝑇𝑧) = 0, then𝑆 and 𝑇 have a unique common fixed point in 𝑋.

Proof. The proof follows by taking 𝑅 = 𝑇 in Theorem 8.

By setting 𝑅 = 𝑇 = 𝑆 inTheorem 8, we have the followingcorollary.

Corollary 12. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑇 : 𝑋 β†’ 𝑋 be a self-mapping satisfying the condition

𝐺 (𝑇π‘₯, 𝑇𝑦, 𝑇𝑧) ≀ 𝐴 β‹… [𝐺 (π‘₯, 𝑇π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑇𝑦, 𝑇𝑧)

+ [𝐺 (π‘₯, 𝑦, 𝑧)]2

+ 𝐺 (π‘₯, 𝑇π‘₯, 𝑇𝑦)𝐺 (π‘₯, 𝑦, 𝑧)]

β‹… (𝐺 (π‘₯, 𝑇π‘₯, 𝑇𝑦) + 𝐺 (π‘₯, 𝑦, 𝑧) + 𝐺 (π‘₯, 𝑇𝑦, 𝑇𝑧))βˆ’1

+ 𝐡 β‹… (𝐺 (𝑦, 𝑇𝑦, 𝑇𝑧) [1 + 𝐺 (π‘₯, 𝑇π‘₯, 𝑇𝑦)]

β‹… (1 + 𝐺 (π‘₯, 𝑦, 𝑧))βˆ’1

) + 𝐢 β‹… 𝐺 (π‘₯, 𝑦, 𝑧)

(18)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴, 𝐡, 𝐢 β‰₯ 0 with0 ≀ 𝐴+𝐡+𝐢 < 1,𝐺(π‘₯, 𝑇π‘₯, 𝑇𝑦)+𝐺(π‘₯, 𝑦, 𝑧)+𝐺(π‘₯, 𝑇𝑦, 𝑇𝑧) = 0.Then, 𝑇 has a unique fixed point. Further, if 𝐺(π‘₯, 𝑇π‘₯, 𝑇𝑦) +

𝐺(π‘₯, 𝑦, 𝑧) + 𝐺(π‘₯, 𝑇𝑦, 𝑇𝑧) = 0 implies 𝐺(𝑇π‘₯, 𝑇𝑦, 𝑇𝑧) = 0, then𝑇 has a unique common fixed point in 𝑋.

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Journal of Function Spaces 5

The second main result in this section is the following.

Theorem 13. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space. Let𝑅, 𝑆, 𝑇, 𝐼, 𝐽, 𝑄 : 𝑋 β†’ 𝑋 be six continuous self-maps and let{𝑆, 𝐼}, {𝑇, 𝐽}, and {𝑅, 𝑄} be weakly commuting pairs of self-mapping such that 𝑇(𝑋) βŠ‚ 𝐼(𝑋), 𝑆(𝑋) βŠ‚ 𝐽(𝑋), and 𝑅(𝑋) βŠ‚

𝑄(𝑋), satisfying the condition

𝐺 (𝑅π‘₯, 𝑆𝑦, 𝑇𝑧) ≀ 𝐴 β‹… [𝐺 (𝑄π‘₯, 𝑆π‘₯, 𝐼𝑧) 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯)

+ [𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)]2

+ 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)] (𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯)

+ 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯))βˆ’1

+ 𝐡

β‹… 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)

(19)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴, 𝐡 β‰₯ 0 with0 ≀ 𝐴+𝐡 < 1,𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯)+𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)+𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) =

0. Then 𝑅, 𝑆, 𝑇, 𝐼, 𝐽, 𝑄 have a common fixed point. Further, if𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) + 𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) = 0 implies𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) + 𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) = 0, then 𝑅, 𝑆, 𝑇, 𝐼, 𝐽, 𝑄 havea unique common fixed point in 𝑋.

Proof. Take π‘₯0as arbitrary point of 𝑋. Since 𝑅(𝑋) βŠ‚ 𝑄(𝑋),

we can find a point π‘₯1in 𝑋 such that 𝑅π‘₯

0= 𝑄π‘₯

1. For

𝑆(𝑋) βŠ‚ 𝐽(𝑋), we can find a point π‘₯2in𝑋 such that𝑅π‘₯

1= 𝑄π‘₯2

and for 𝑇(𝑋) βŠ‚ 𝐼(𝑋) we can find a point π‘₯3in 𝑋 such that

𝑇π‘₯2= 𝐼π‘₯3. Generally, for a point π‘₯

3𝑛, choose π‘₯

3𝑛+1such that

𝑅π‘₯3𝑛

= 𝑄π‘₯3𝑛+1

; for a point π‘₯3𝑛+1

, choose π‘₯3𝑛+2

such that𝑆π‘₯3𝑛+1

= 𝐽π‘₯3𝑛+2

; and for a point π‘₯3𝑛+2

, choose π‘₯3𝑛+3

such that𝑇π‘₯3𝑛+2

= 𝐼π‘₯3𝑛+3

for 𝑛 = 0, 1, 2, 3, . . ..Suppose 𝐺

3𝑛= 𝐺(𝑅π‘₯

3𝑛, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) = 0 and 𝐺3𝑛+1

=

𝐺(𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+2

, 𝑇π‘₯3𝑛+3

) = 0. Then, from condition (19), wehave

𝐺3𝑛+1

= 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+2

, 𝑇π‘₯3𝑛+3

) ≀ 𝐴

β‹… [𝐺 (𝑄π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝐼π‘₯3𝑛+3

)

β‹… 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝐼π‘₯3𝑛+1

)

+ [𝐺 (𝑄π‘₯3𝑛+1

, 𝐽π‘₯3𝑛+2

, 𝐼π‘₯3𝑛+3

)]2

+ 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝐼π‘₯3𝑛+1

)

β‹… 𝐺 (𝑄π‘₯3𝑛+1

, 𝐽π‘₯3𝑛+2

, 𝐼π‘₯3𝑛+3

)]

β‹… [𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝐼π‘₯3𝑛+1

)

+ 𝐺 (𝑄π‘₯3𝑛+1

, 𝐽π‘₯3𝑛+2

, 𝐼π‘₯3𝑛+3

)

+ 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝐼π‘₯3𝑛+1

)]βˆ’1

+ 𝐡

β‹… 𝐺 (𝑄π‘₯3𝑛+1

, 𝐽π‘₯3𝑛+2

, 𝐼π‘₯3𝑛+3

) = 𝐴

β‹… [𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

)

β‹… 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛

)

+ [𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

)]2

+ 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛

)

β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

)]

β‹… [𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛

)

+ 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

)

+ 𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛

)]βˆ’1

+ 𝐡

β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) = 𝐴

β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) + 𝐡

β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) = (𝐴 + 𝐡)

β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) .

(20)

Hence,

𝐺 (𝑅π‘₯3𝑛+1

, 𝑆π‘₯3𝑛+2

, 𝑇π‘₯3𝑛+3

)

≀ (𝐴 + 𝐡) β‹… 𝐺 (𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) ,

𝐺3𝑛+1

≀ β„Ž β‹… 𝐺3𝑛

,

(21)

where β„Ž = 𝐴 + 𝐡. Continuing this procedure, in the end weget

𝐺3𝑛+1

≀ β„Ž β‹… 𝐺3𝑛

≀ β„Ž2

β‹… 𝐺3π‘›βˆ’1

≀ β„Ž3

β‹… 𝐺3π‘›βˆ’2

≀ β„Ž4

β‹… 𝐺3π‘›βˆ’3

≀ β‹… β‹… β‹… ≀ β„Ž3𝑛+1

β‹… 𝐺0.

(22)

Clearly, 𝐺3𝑛+1

β†’ 0 as 𝑛 β†’ ∞. So, 𝐺(𝑅π‘₯3𝑛

, 𝑆π‘₯3𝑛+1

, 𝑇π‘₯3𝑛+2

) β†’

0; we get the following sequence:

{𝑅π‘₯0, 𝑆π‘₯1, 𝑇π‘₯2, 𝑅π‘₯3, 𝑆π‘₯4, 𝑇π‘₯5, 𝑅π‘₯6, 𝑆π‘₯7, 𝑇π‘₯8, . . . , 𝑅π‘₯

3𝑛+1,

𝑆π‘₯3𝑛+2

, 𝑇π‘₯3𝑛+3

, . . .} ,

(23)

which is a Cauchy sequence in 𝐺-complete 𝐺-metric spaceand therefore converges to a limit point 𝑀. But all subse-quences of a convergent sequence converge; so, we have

limπ‘›β†’βˆž

𝑅π‘₯3𝑛

= limπ‘›β†’βˆž

𝑄π‘₯3𝑛+1

= 𝑀,

limπ‘›β†’βˆž

𝑆π‘₯3𝑛

= limπ‘›β†’βˆž

𝐽π‘₯3𝑛+1

= 𝑀,

limπ‘›β†’βˆž

𝑇π‘₯3π‘›βˆ’1

= limπ‘›β†’βˆž

𝐼π‘₯3𝑛

= 𝑀.

(24)

Since {𝑆, 𝐼} are weakly commuting mappings, thus we have

𝐺 (𝑆𝐼π‘₯3𝑛

, 𝐼𝑆π‘₯3𝑛

, 𝐼𝑆π‘₯3𝑛

) ≀ 𝐺 (𝐼π‘₯3𝑛

, 𝑆π‘₯3𝑛

, 𝑆π‘₯3𝑛

) . (25)

Taking limit 𝑛 β†’ ∞ and noting that 𝑆 and 𝐼 are continuousmappings, we have

𝐺 (𝑆𝑀, 𝐼𝑀, 𝐼𝑀) ≀ 𝐺 (𝑀,𝑀, 𝑀) , (26)

Page 6: Research Article Fixed Point Results Satisfying Rational ...downloads.hindawi.com/journals/jfs/2016/9536765.pdfpoint theory, metric xed point theory, and discrete x ed pointtheory.

6 Journal of Function Spaces

which gives the notion that 𝑆𝑀 = 𝐼𝑀. Analogously, we canget 𝑇𝑀 = 𝐽𝑀 and 𝑅𝑀 = 𝑄𝑀. We claim that 𝑅𝑀 = 𝑆𝑀 and𝑆𝑀 = 𝑇𝑀 and then from condition (3)

𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀) ≀ 𝐴

β‹… [𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀)𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀)

+ [𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)]2

+ 𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀)𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)]

β‹… (𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀) + 𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)

+ 𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀))βˆ’1

+ 𝐡 β‹… 𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀) ,

𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀) ≀ (𝐴 + 𝐡)𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀) ,

(27)

which is a contraction:

𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀) = 0 implies 𝑅𝑀 = 𝑆𝑀 = 𝑇𝑀. (28)

Similarly, using similar arguments to those given above, weobtain a contradiction for 𝑅𝑀 = 𝑆𝑀 and 𝑆𝑀 = 𝑇𝑀 or for𝑅𝑀 = 𝑆𝑀 and 𝑆𝑀 = 𝑇𝑀. Hence, in all the cases, we concludethat 𝑅𝑀 = 𝑆𝑀 = 𝑇𝑀. We prove that any fixed point of 𝑅 is afixed point of 𝑆, 𝑇, 𝑄, 𝐼, and 𝐽. Assume that𝑀 ∈ 𝑋 is such that𝑅𝑀 = 𝑀. Now, we prove that 𝑀 = 𝑇𝑀 = 𝑆𝑀. If it is not thecase, then, for 𝑀 = 𝑆𝑀 and 𝑀 = 𝑇𝑀, we get

𝐺 (𝑀, 𝑆𝑀, 𝑇𝑀) = 𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀) ≀ 𝐴

β‹… [𝐺 (𝑅𝑀, 𝑆𝑀, 𝑇𝑀)𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀)

+ [𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)]2

+ 𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀)𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)]

β‹… (𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀) + 𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀)

+ 𝐺 (𝑅𝑀, 𝑆𝑀, 𝑆𝑀))βˆ’1

+ 𝐡 β‹… 𝐺 (𝑅𝑀, 𝑇𝑀, 𝑆𝑀) ,

𝐺 (𝑀, 𝑆𝑀, 𝑇𝑀) ≀ (𝐴 + 𝐡)𝐺 (𝑀, 𝑇𝑀, 𝑆𝑀) ,

(29)

where 𝐺(𝑀, 𝑆𝑀, 𝑇𝑀) = 0 which implies that 𝑀 = 𝑆𝑀 = 𝑇𝑀;in a similar argument, we can prove the other cases.

Uniqueness. Suppose that 𝑆, 𝑇, 𝑅, 𝐼, 𝐽, and 𝑄 have two com-mon fixed points 𝑧 and 𝑀 such that 𝑧 = 𝑀. Since condition𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) + 𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) = 0 implies𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧)+𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) = 0, we have that𝐺(𝑅𝑧, 𝑆𝑧, 𝐼𝑧)+

𝐺(𝑄𝑧, 𝐽𝑧, 𝐼𝑀) + 𝐺(𝑅𝑧, 𝑆𝑧, 𝐼𝑧) = 0 implies 𝐺(𝑆𝑧, 𝑇𝑧, 𝑅𝑀) +

𝐺(𝑄𝑧, 𝐽𝑧, 𝐼𝑀) = 0, which can be written as𝐺(𝑆𝑧, 𝑇𝑧, 𝑅𝑀) = 0

or 𝐺(𝑄𝑧, 𝐽𝑧, 𝐼𝑀) = 0.Therefore, one can get the following:

𝐺 (𝑧, 𝑧, 𝑀) = 0

or 𝐺 (𝑧, 𝑧, 𝑀) = 0 implies that 𝑧 = 𝑀.

(30)

Theorem 13 produces the following corollaries.

Corollary 14. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑅, 𝑆, 𝑇, 𝐼, 𝐽, 𝑄 : 𝑋 β†’ 𝑋 be three self-maps and let {𝑆, 𝐼},{𝑇, 𝐽}, and {𝑅, 𝑄} be weakly commuting pairs of self-mappingsuch that 𝑇(𝑋) βŠ‚ 𝐼(𝑋), 𝑆(𝑋) βŠ‚ 𝐽(𝑋), and 𝑅(𝑋) βŠ‚ 𝑄(𝑋),satisfying

𝐺 (𝑅π‘₯, 𝑆𝑦, 𝑇𝑧) ≀ 𝐡 β‹… 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) (31)

for all π‘₯, 𝑦, 𝑧 in 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ with 0 ≀ 𝐡 < 1. Then,𝑅, 𝑆, 𝑇, 𝐼, 𝐽, and 𝑄 have a unique common fixed point in 𝑋.

Proof. It follows by taking 𝐴 = 0 in Theorem 13.

Corollary 15. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑅, 𝑆, 𝑇, 𝐼, 𝐽, 𝑄 : 𝑋 β†’ 𝑋 be three self-maps and let {𝑆, 𝐼},{𝑇, 𝐽}, and {𝑅, 𝑄} be weakly commuting pairs of self-mappingsuch that 𝑇(𝑋) βŠ‚ 𝐼(𝑋), 𝑆(𝑋) βŠ‚ 𝐽(𝑋), and 𝑅(𝑋) βŠ‚ 𝑄(𝑋),satisfying

𝐺 (𝑅π‘₯, 𝑆𝑦, 𝑇𝑧) ≀ 𝐴 β‹… [𝐺 (𝑄π‘₯, 𝑆π‘₯, 𝐼𝑧) 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯)

+ [𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)]2

+ 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧)] (𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯)

+ 𝐺 (𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺 (𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯))βˆ’1

+ 𝐡

β‹… 𝐺 (𝑅𝑧, 𝑇𝑧, 𝑆𝑧)

(32)

for all π‘₯, 𝑦, 𝑧 in 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴 β‰₯ 0 with 0 ≀

𝐴 < 1, 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) + 𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) = 0.Then, 𝑅, 𝑆, 𝑇, 𝐼, 𝐽, and 𝑄 have a common fixed point. Further,if 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) + 𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺(𝑅π‘₯, 𝑆π‘₯, 𝐼π‘₯) = 0 implies𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧)+𝐺(𝑄π‘₯, 𝐽𝑦, 𝐼𝑧) = 0, then𝑅, 𝑆, 𝑇, 𝐼, 𝐽, and𝑄 havea unique common fixed point in 𝑋.

Proof. It follows by taking 𝐡 = 0 in Theorem 13.

Corollary 16. Let (𝑋, 𝐺) be a 𝐺-complete 𝐺-metric space andlet 𝑇, 𝑅, 𝐼, 𝐽 : 𝑋 β†’ 𝑋 be three self-maps and let {𝑇, 𝐼}, {𝑇, 𝐽},and {𝑅, 𝐼} be weakly commuting pairs of self-mapping such that𝑇(𝑋) βŠ‚ 𝐼(𝑋), 𝑇(𝑋) βŠ‚ 𝐽(𝑋), and 𝑅(𝑋) βŠ‚ 𝐼(𝑋), satisfying

𝐺 (𝑅π‘₯, 𝑇𝑦, 𝑇𝑧) ≀ 𝐴 β‹… [𝐺 (𝐼π‘₯, 𝑇π‘₯, 𝐼𝑧) 𝐺 (𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯)

+ [𝐺 (𝐼π‘₯, 𝐽𝑦, 𝐼𝑧)]2

+ 𝐺 (𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯) 𝐺 (𝐼π‘₯, 𝐽𝑦, 𝐼𝑧)]

β‹… (𝐺 (𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯) + 𝐺 (𝐼π‘₯, 𝐽𝑦, 𝐼𝑧)

+ 𝐺 (𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯))βˆ’1

+ 𝐡 β‹… 𝐺 (𝐼π‘₯, 𝐽𝑦, 𝐼𝑧)

(33)

for all π‘₯, 𝑦, 𝑧 ∈ 𝑋 with π‘₯ = 𝑦 = 𝑧 = π‘₯ 𝐴, 𝐡 β‰₯ 0 with0 ≀ 𝐴+𝐡 < 1,𝐺(𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯)+𝐺(𝐼π‘₯, 𝐽𝑦, 𝐼𝑧)+𝐺(𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯) =

0. Then, 𝑇, 𝑅, 𝐼, and 𝐽 have a common fixed point. Further,if 𝐺(𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯) + 𝐺(𝐼π‘₯, 𝐽𝑦, 𝐼𝑧) + 𝐺(𝑅π‘₯, 𝑇π‘₯, 𝐼π‘₯) = 0 implies𝐺(𝑆π‘₯, 𝑇𝑦, 𝑅𝑧) + 𝐺(𝐼π‘₯, 𝐽𝑦, 𝐼𝑧) = 0, then 𝑇, 𝑅, 𝐼, and 𝐽 have aunique common fixed point in 𝑋.

Proof. The proof follows by setting 𝑆 = 𝑇 and 𝐼 = 𝑄 inTheorem 13.

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Journal of Function Spaces 7

Competing Interests

The authors declare that they have no competing interests.

References

[1] S. Aleomraninejad, S. Rezapour, and N. Shahzad, β€œFixed pointresults on subgraphs of directed graphs,”Mathematical Sciences,vol. 7, article 41, 2013.

[2] K. C. Border, Fixed Point Theorems with Applications to Eco-nomics and Game Theory, Cambridge University Press, Cam-bridge, Uk, 1985.

[3] S. Banach, β€œSur les oprations dans les ensembles abstraitset leurs applications aux equations integrales,” FundamentaMathematicae, vol. 3, pp. 133–181, 1922.

[4] Ya. I. Alber and S. Guerre-Delabriere, β€œPrinciple of weaklycontractive maps in Hilbert spaces,” in New Results in OperatorTheory and Its Applications, I. Gohberg and Yu. Lyubich, Eds.,vol. 98 ofOperatorTheory: Advances and Applications, pp. 7–22,Springer, New York, NY, USA, 1997.

[5] R. P. Agarwal, Z. Kadelburg, and S. Radenovic, β€œOn coupledfixed point results in asymmetric G-metric spaces,” Journal ofInequalities and Applications, vol. 2013, article 528, 2013.

[6] A. Branciari, β€œA fixed point theorem for mappings satisfyinga general contractive condition of integral type,” InternationalJournal of Mathematics and Mathematical Sciences, vol. 29, no.9, pp. 531–536, 2002.

[7] D. S. Jaggi, β€œSome unique fixed point theorems,” Indian Journalof Pure and AppliedMathematics, vol. 8, no. 2, pp. 223–230, 1977.

[8] M. Abbas and T. Nazir, β€œFixed points of T-Hardy Rogers typecontraction mapping in metric spaces,” Afrika Matematika, vol.25, no. 1, pp. 103–113, 2014.

[9] M. Abbas, T. Nazir, and S. Radenovic, β€œSome periodic pointresults in generalized metric spaces,” Applied Mathematics andComputation, vol. 217, no. 8, pp. 4094–4099, 2010.

[10] M. Abbas, T. Nazir, and S. Radenovic, β€œCommon fixed pointof generalized weakly contractive maps in partially ordered G-metric spaces,” Applied Mathematics and Computation, vol. 218,no. 18, pp. 9383–9395, 2012.

[11] S. Radenovic, β€œRemarks on some recent coupled coincidencepoint results in symmetric G-metric spaces,” Journal of Opera-tors, vol. 2013, Article ID 290525, 8 pages, 2013.

[12] B. K. Dass and S. Gupta, β€œAn extension of Banach contractionprinciple through rational expression,” Indian Journal of Pureand Applied Mathematics, vol. 6, no. 12, pp. 1455–1458, 1975.

[13] J. Harjani, B. Lopez, and K. Sadarangani, β€œA fixed point theoremfor mappings satisfying a contractive condition of rationaltype on a partially ordered metric space,” Abstract and AppliedAnalysis, vol. 2010, Article ID 190701, 8 pages, 2010.

[14] N. V. Luong and N. X. Thuan, β€œFixed point theorem forgeneralized weak contractions satisfying rational expressions inorderedmetric spaces,” Fixed PointTheory andApplications, vol.2011, article 46, 2011.

[15] S. Chandok and E. Karapinar, β€œCommon fixed point of gener-alized rational type contraction mappings in partially orderedmetric spaces,” Thai Journal of Mathematics, vol. 11, no. 2, pp.251–260, 2013.

[16] Z. Mustafa, E. Karapinar, and H. Aydi, β€œA discussion on gener-alized almost contractions via rational expressions in partiallyordered metric spaces,” Journal of Inequalities and Applications,vol. 2014, article 219, 2014.

[17] S. Chandok and J. K. Kim, β€œFixed point theorem in orderedmetric spaces for generalized contractions mappings satisfyingrational type expressions,” Journal of Nonlinear FunctionalAnalysis and Applications, vol. 17, pp. 301–306, 2012.

[18] S. Chandok, M. S. Khan, and K. P. R. Rao, β€œSome coupledcommon fixed point theorems for a pair of mappings satisfyinga contractive condition of rational type,” Journal of NonlinearAnalysis and Application, vol. 2013, Article ID jnaa-00174, 6pages, 2013.

[19] D. S. Jaggi and B. K. Dass, β€œAn extension of Banach’s fixed pointtheorem through a rational expression,” Bulletin of the CalcuttaMathematical Society, vol. 72, no. 5, pp. 261–262, 1980.

[20] B. G. Pachpatte, β€œCommon fixed-point theorems for mappingssatisfying rational inequalities,” Indian Journal of Pure andApplied Mathematics, vol. 10, no. 11, pp. 1362–1368, 1979.

[21] Z. Mustafa and B. Sims, β€œA new approach to generalized metricspaces,” Journal of Nonlinear and Convex Analysis, vol. 7, no. 2,pp. 289–297, 2006.

[22] S. Manro, S. S. Bhatia, S. Kumar, and C. Vetro, β€œA commonfixed point theorem for two weakly compatible pairs in G-metric spaces using the property E.A,” Fixed Point Theory andApplications, vol. 2013, article 41, 2013.

[23] H. K. Nashine and Z. Kadelburg, β€œNonlinear generalized cycliccontractions in complete 𝐺-metric spaces and applications tointegral equations,” Nonlinear Analysis: Modelling and Control,vol. 18, no. 2, pp. 160–176, 2013.

[24] R. Saadati, S. M. Vaezpour, P. Vetro, and B. E. Rhoades,β€œFixed point theorem in generalized partially ordered G-metricspaces,”Mathematical and Computer Modelling, vol. 52, no. 5-6,pp. 797–801, 2010.

[25] P. L. Sanodia, D. Jaiswal, and S. S. Rajput, β€œFixed point theoremsin G-metric spaces via rational type contractive condition,”International Journal of Mathematical Archive, vol. 3, no. 3, pp.1292–1296, 2012.

[26] M. P. Gandhi and K. B. Bajpai, β€œUnique common fixedpoint theorem in G-Metric space via rational type contractivecondition,” in Proceedings of the International Conference onBenchmarks in Engineering Science and Technology, pp. 1–4,September 2012.

[27] R. Shrivastava, M. Sharma, and R. Bhardwaj, β€œFixed pointresults in G-Metric spaces through rational contractive condi-tions,” International Journal of Theoretical and Applied Sciences,vol. 6, pp. 82–88, 2014.

[28] S. Manro, S. S. Bhatia, and S. Kumar, β€œExpansion mappingstheorems in G-metric spaces,” International Journal of Contem-porary Mathematical Sciences, vol. 5, no. 49-52, pp. 2529–2535,2010.

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