11
Miskolc Mathematical Notes HU e-ISSN 1787-2413 Vol. 18 (2017), No. 2, pp. 611–621 DOI: 10.18514/MMN.2017.1379 FIXED POINT RESULTS FOR GENERALIZED RATIONAL ˛-GERAGHTY CONTRACTION MUHAMMAD ARSHAD AND AFTAB HUSSAIN Received 15 October, 2014 Abstract. In this paper, an effort has been made to improve the notion of ˛-Geraghty contrac- tion type mappings and establish some common fixed point theorems for a pair of ˛-admissible mappings under the improved approach of generalized rational ˛-Geraghty contractive type con- dition in a complete metric space. An example has been constructed to demonstrate the novelty of these results. 2010 Mathematics Subject Classification: 46S40; 47H10; 54H25 Keywords: fixed point, contraction type mapping, rational ˛-Geraghty contraction type map- ping, triangular ˛-admissible, metric space 1. PRELIMINARIES AND SCOPE In 1973, Geraghty [3] studied a generalization of Banach contraction principle. He generalized the Banach contraction principle in a different way than it was done by different investigators. In 2012, Samet et al. [16], introduced a concept of ˛ - con- tractive type mappings and established various fixed point theorems for mappings in complete metric spaces. Afterwards, Karapinar [11], refined the notion and obtained various fixed point results. See more results in [9]. Hussain et al. [7], generalized the concept of ˛-admissible mappings and proved fixed point theorems. Subsequently, Abdeljawad [1] introduced a pair of ˛admissible mappings satisfying new suffi- cient contractive conditions different from those in [7], [16] and obtained fixed point and common fixed point theorems. Salimi et al. [15], modified the concept of ˛ contractive mappings and established fixed point results. Recently, Hussain et al. [8] proved some fixed point results for single and set-valued ˛ -contractive map- pings in the setting of complete metric space. Mohammadi et al. [13], introduced a new notion of ˛ contractive mappings and showed that it was a real gener- alization for some old results. Thereafter, many papers have published on geraghty contractions. For more detail see [46, 8, 11, 14] and references therein. Definition 1 ([16]). Let S W X ! X and ˛ W X X ! R. We say that S is ˛- admissible if x;y 2 X; ˛.x;y/ 1 ) ˛.Sx;Sy/ 1: c 2017 Miskolc University Press

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Page 1: FIXED POINT RESULTS FOR GENERALIZED RATIONAL …mat76.mat.uni-miskolc.hu/mnotes/download_article/1379.pdf · Miskolc Mathematical Notes HU e-ISSN 1787-2413 Vol. 18 (2017), No. 2,

Miskolc Mathematical Notes HU e-ISSN 1787-2413Vol. 18 (2017), No. 2, pp. 611–621 DOI: 10.18514/MMN.2017.1379

FIXED POINT RESULTS FOR GENERALIZED RATIONAL˛-GERAGHTY CONTRACTION

MUHAMMAD ARSHAD AND AFTAB HUSSAIN

Received 15 October, 2014

Abstract. In this paper, an effort has been made to improve the notion of ˛-Geraghty contrac-tion type mappings and establish some common fixed point theorems for a pair of ˛-admissiblemappings under the improved approach of generalized rational ˛-Geraghty contractive type con-dition in a complete metric space. An example has been constructed to demonstrate the noveltyof these results.

2010 Mathematics Subject Classification: 46S40; 47H10; 54H25

Keywords: fixed point, contraction type mapping, rational ˛-Geraghty contraction type map-ping, triangular ˛-admissible, metric space

1. PRELIMINARIES AND SCOPE

In 1973, Geraghty [3] studied a generalization of Banach contraction principle. Hegeneralized the Banach contraction principle in a different way than it was done bydifferent investigators. In 2012, Samet et al. [16], introduced a concept of ˛� - con-tractive type mappings and established various fixed point theorems for mappings incomplete metric spaces. Afterwards, Karapinar [11], refined the notion and obtainedvarious fixed point results. See more results in [9]. Hussain et al. [7], generalized theconcept of ˛-admissible mappings and proved fixed point theorems. Subsequently,Abdeljawad [1] introduced a pair of ˛�admissible mappings satisfying new suffi-cient contractive conditions different from those in [7], [16] and obtained fixed pointand common fixed point theorems. Salimi et al. [15], modified the concept of ˛� �contractive mappings and established fixed point results. Recently, Hussain et al. [8]proved some fixed point results for single and set-valued ˛��� -contractive map-pings in the setting of complete metric space. Mohammadi et al. [13], introduceda new notion of ˛���contractive mappings and showed that it was a real gener-alization for some old results. Thereafter, many papers have published on geraghtycontractions. For more detail see [4–6, 8, 11, 14] and references therein.

Definition 1 ([16]). Let S W X ! X and ˛ W X �X ! R. We say that S is ˛-admissible if x;y 2X; ˛.x;y/� 1) ˛.Sx;Sy/� 1:

c 2017 Miskolc University Press

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612 MUHAMMAD ARSHAD AND AFTAB HUSSAIN

Example 1 ([12]). Consider X D Œ0;1/, and define S WX !X and ˛ WX �X !Œ0;1/ by Sx D 2x; for all x;y 2X and

˛ .x;y/D

�e

yx ; if x � y;x ¤ 00; if x < y:

Then S is ˛�admissible.

Definition 2 ([1]). Let S;T W X ! X and ˛ W X �X ! Œ0;C1/. We say thatthe pair .S;T / is ˛-admissible if x;y 2 X such that ˛.x;y/ � 1, then we have˛.Sx;Ty/� 1 and ˛.T x;Sy/� 1:

Definition 3 ([10]). Let S W X ! X and ˛ W X �X ! Œ0;C1/. We say that S istriangular ˛-admissible if x;y 2X; ˛.x;´/� 1 and ˛.´;y/� 1) ˛.x;y/� 1:

Definition 4 ([10]). Let S WX !X and ˛ WX �X ! .�1;C1/. We say that Sis a triangular ˛-admissible mapping if

(T1) ˛.x;y/� 1 implies ˛.Sx;Sy/� 1; x;y 2X ,(T2) ˛.x;´/� 1, ˛.´;y/� 1, implies ˛.x;y/� 1, x;y;´ 2X .

Definition 5 ([1]). Let S;T W X ! X and ˛ W X �X ! .�1;C1/. We say thata pair .S;T / is triangular ˛-admissible if

(T1) ˛.x;y/� 1, implies ˛.Sx;Ty/� 1 and ˛.T x;Sy/� 1; x;y 2X:(T2) ˛.x;´/� 1, ˛.´;y/� 1, implies ˛.x;y/� 1, x;y;´ 2X .

Definition 6 ([15]). Let S W X ! X and let ˛;� W X �X ! Œ0;C1/ be twofunctions. We say that T is ˛-admissible mapping with respect to � if x;y 2 X;˛.x;y/� �.x;y/) ˛.Sx;Sy/� �.Sx;Sy/: Note that if we take �.x;y/D 1; thenthis definition reduces to definition in [16]. Also if we take ˛.x;y/D 1; then we saysthat S is an �-subadmissible mapping.

Lemma 1 ([2]). Let S W X ! X be a triangular ˛-admissible mapping. Assumethat there exists x0 2X such that ˛.x0;Sx0/� 1:Define a sequence fxng by xnC1DSxn: Then we have ˛.xn;xm/� 1 for all m;n 2N[f0g with n < m:

Lemma 2. Let S;T W X ! X be a triangular ˛-admissible mapping. Assumethat there exists x0 2 X such that ˛.x0;Sx0/ � 1: Define sequence x2iC1 D Sx2i ;and x2iC2 D T x2iC1, where i D 0;1;2; : : : :: Then we have ˛.xn;xm/ � 1 for allm;n 2N[f0g with n < m:

We denote by˝ the family of all functions ˇ W Œ0;C1/! Œ0;1/ such that, for anybounded sequence ftng of positive reals, ˇ.tn/! 1 implies tn! 0.

Theorem 1 ([3]). Let .X;d/ be a metric space. Let S WX!X be a self mapping.Suppose that there exists ˇ 2˝ such that for all x;y 2X ,

d.Sx;Sy/� ˇ .d.x;y//d.x;y/:

then S has a fixed unique point p 2X and fSnxg converges to p for each x 2X .

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FIXED POINT RESULTS FOR G-RATIONAL ˛-GERAGHTY CONTRACTION 613

2. RESULTS

In this section, we prove some fixed point theorems satisfying generalized rational˛-Geraghty contraction type mappings in complete metric space. Let .X;d/ be ametric space, and let ˛ WX �X! R be a function. Let S;T WX!X is called a pairof generalized rational ˛-Geraghty contraction type mappings if there exists ˇ 2 ˝such that for all x;y 2X ,

˛.x;y/d.Sx;Ty/� ˇ .M.x;y//M.x;y/ (2.1)

where

M.x;y/Dmax�d.x;y/;

d.x;Sx/d.y;Ty/

1Cd.x;y/;d.x;Sx/d.y;Ty/

1Cd.Sx;Ty/

�:

If S D T then T is called generalized rational ˛-Geraghty contraction type mappingsif there exists ˇ 2˝ such that for all x;y 2X ,

˛.x;y/d.T x;Ty/� ˇ .N.x;y//N.x;y/

where

N.x;y/Dmax�d.x;y/;

d.x;T x/d.y;Ty/

1Cd.x;y/;d.x;T x/d.y;Ty/

1Cd.T x;Ty/

�:

Theorem 2. Let .X;d/ be a complete metric space, ˛ WX �X! R be a function.Let S;T WX !X be two mappings then suppose that the following holds:

(i) .S;T / is pair of generalized rational ˛-Geraghty contraction type mapping;(ii) .S;T / is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� 1;(iv) S and T are continuous;Then .S;T / have common fixed point.

Proof. Let x1 inX be such that x1D Sx0 and x2D T x1. Continuing this process,we construct a sequence xn of points in X such that,

x2iC1 D Sx2i ; and x2iC2 D T x2iC1, where i D 0;1;2; : : : : (2.2)

By assumption ˛.x0;x1/� 1 and pair .S;T / is ˛ -admissible, by Lemma 2, we have

˛.xn;xnC1/� 1 for all n 2N[f0g: (2.3)

Then

d.x2iC1;x2iC2/D d.Sx2i ;T x2iC1/� ˛.x2i ;x2iC1/d.Sx2i ;T x2iC1/

� ˇ .M.x2i ;x2iC1//M.x2i ;x2iC1/;

for all i 2N[f0g: Now

M.x2i ;x2iC1/Dmax�d.x2i ;x2iC1/;

d.x2i ;Sx2i /d.x2iC1;T x2iC1/

1Cd.x2i ;x2iC1/;d.x2i ;Sx2i /d.x2iC1;T x2iC1/

1Cd.Sx2i ;T x2iC1/

�Dmax

�d.x2i ;x2iC1/;

d.x2i ;x2iC1/d.x2iC1;x2iC2/

1Cd.x2i ;x2iC1/;d.x2i ;x2iC1/d.x2iC1;x2iC2/

1Cd.x2iC1;x2iC2/

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614 MUHAMMAD ARSHAD AND AFTAB HUSSAIN

�max˚d.x2i ;x2iC1/;d.x2iC1;x2iC2/

:

Thus

d.x2iC1;x2iC2/� ˇ .M.x2i ;x2iC1//M.x2i ;x2iC1/

� ˇ .d.x2i ;x2iC1//d..x2i ;x2iC1/ < d.x2i ;x2iC1/:

so that,d..x2iC1;x2iC2/ < d.x2i ;x2iC1/: (2.4)

This implies that

d.xnC1;xnC2/ < d.xn;xnC1/; for all n 2N[f0g: (2.5)

So, sequence fd.xn;xnC1/g is nonnegative and nonincreasing. Now, we prove thatd.xn;xnC1/! 0: It is clear that fd.xn;xnC1/g is a decreasing sequence. Therefore,there exists some positive number r such that limn!1d.xn;xnC1/D r: From .2:4/;

we haved.xnC1;xnC2/

d.xn;xnC1/� ˇ.d.xn;xnC1//� 1:

Now by taking limit n!1; we have

1� ˇ.d.xn;xnC1//� 1;

that islimn!1

ˇ.d.xn;xnC1//D 1:

By the property of ˇ, we have

limn!1

d.xn;xnC1/D 0: (2.6)

Now, we show that sequence fxng is Cauchy sequence. Suppose on contrary thatfxng is not a Cauchy sequence. Then there exists � > 0 and sequences fxmk

g andfxnkg such that, for all positive integers k, we have mk > nk > k,

d.xmk;xnk

/� � (2.7)

andd.xmk

;xnk�1/ < �: (2.8)

By the triangle inequality, we have

� � d.xmk;xnk

/

� d.xmk;xnk�1

/Cd.xnk�1;xnk

/

< �Cd.xnk�1;xnk

/:

That is,� < �Cd.xnk�1

;xnk/ (2.9)

for all k 2N. In the view of .2:9/, .2:6/; we have

limk!1

d.xmk;xnk

/D �: (2.10)

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FIXED POINT RESULTS FOR G-RATIONAL ˛-GERAGHTY CONTRACTION 615

Again using triangle inequality, we have

d.xmk;xnk

/� d.xmk;xmkC1

/Cd.xmkC1;xnkC1

/Cd.xnkC1;xnk

/

and

d.xmkC1;xnkC1

/� d.xmkC1;xmk

/Cd.xmk;xnk

/Cd.xnk;xnkC1

/:

Taking limit as k!C1 and using .2:6/ and .2:10/; we obtain

limk!C1

d.xmkC1;xnkC1

/D �: (2.11)

By Lemma 2, ˛.xnk;xmkC1

/� 1; we have

d.xnkC1;xmkC2

/D d.Sxnk;T xmkC1

/� ˛.xnk;xmkC1

/d.Sxnk;T xmkC1

/

� ˇ.M.xnk;xmkC1

//M.xnk;xmkC1

/:

Finally, we conclude thatd.xnkC1

;xmkC2/

M.xnk;xmkC1

/� ˇ.M.xnk

;xmkC1//:

By using .2:6/, taking limit as k!C1 in the above inequality; we obtain

limk!1

ˇ.d.xnk;xmkC1

//D 1: (2.12)

So, limk!1d.xnk;xmkC1

/ D 0 < �; which is a contradiction. Hence fxng is aCauchy sequence. Since X is complete so there exists p 2 X such that xn ! p

implies that x2iC1 ! p and x2iC2 ! p. As S and T are continuous, so we getT x2iC1 ! Tp and Sx2iC2 ! Sp . Thus p D Sp similarly, p D Tp; we haveSp D Tp D p: Then .S;T / have common fixed point. �

In the following Theorem, we dropped continuity.

Theorem 3. Let .X;d/ be a complete metric space, ˛ WX �X! R be a function.Let S;T WX !X be two mappings then suppose that the following holds:

(i) .S;T / is a pair of generalized rational ˛ -Geraghty contraction type mapping;(ii) .S;T / is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� 1;(iv) if fxng is a sequence in X such that ˛.xn;xnC1/ � 1 for all n 2N[f0g and

xn! p 2 X as n!C1; then there exists a subsequencefxnkg of fxng such that

˛.xnk;p/� 1 for all k:

Then .S;T / have common fixed point.

Proof. Follows the similar lines of the Theorem 2. Define a sequence x2iC1 DSx2i ; and x2iC2 D T x2iC1, where i D 0;1;2; : : : : converges to p 2X: By the hypo-theses of (iv) there exists a subsequencefxnk

g of fxng such that ˛.x2nk;p/ � 1 for

all k: Now by using .2:1/ for all k; we have

d.x2nkC1;Tp/D d.Sx2nk;Tp/� ˛.x2nk

;p/d.Sx2nk;Tp/

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616 MUHAMMAD ARSHAD AND AFTAB HUSSAIN

� ˇ�M.x2nk

;p/�M.x2nk

;p/:

so that,d.x2nkC1;Tp/� ˇ

�M.x2nk

;p/�M.x2nk

;p/: (2.13)On the other hand, we obtain

M.x2nk;p/Dmax

�d.x2nk

;p/;d.x2nk

;Sx2nk/;d.p;Tp/

1Cd.x2nk;p/

;d.x2nk

;Sx2nk/;d.p;Tp/

1Cd.Sx2nk;Tp/

�:

Letting k!1 then we have

limk!1

M.x2nk;p/Dmaxfd.p;Sp/;d.p;Tp/g : (2.14)

Case I.limk!1M.x2nk

;p/ D d.p;Tp/: Suppose that d.p;Tp/ > 0. From .2:14/, for alarge k , we have M.x2nk

;p/ > 0, which implies that

ˇ.M.x2nk;p// <M.x2nk

;p/:

Then, we haved.x2nk

;Tp/ <M.x2nk;p/ (2.15)

Letting k!1 in .2:15/, we obtain that d.p;Tp/ < d.p;Tp/, which is a contradic-tion. Thus, we find that d.p;Tp/D 0, implies p D Tp:Case II.limk!1M.x2nk

;p/D d.p;Sp/: Similarly p D Sp: Thus p D Tp D Sp: �

IfM.x;y/Dmax�d.x;y/;

d.x;Sx/d.y;Sy/

1Cd.x;y/;d.x;Sx/d.y;Sy/

1Cd.Sx;Sy/

�and S D T in

Theorem 2 and Theorem 3 , we have the following corollaries.

Corollary 1. Let .X;d/ be a complete metric space and let S is ˛� admissiblemappings such that the following holds:

(i) S is a generalized rational ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;T .x0//� 1;(iv) S is continuous;Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0g

converges to p.

Corollary 2. Let .X;d/ be a complete metric space and let S is ˛� admissiblemappings such that the following holds:

(i) S is a generalized rational ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� 1;(iv) if fxng is a sequence in X such that ˛.xn;xnC1/ � 1 for all n 2N[f0g and

xn! p 2 X as n!C1; then there exists a subsequencefxnkg of fxng such that

˛.xnk;p/� 1 for all k:

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FIXED POINT RESULTS FOR G-RATIONAL ˛-GERAGHTY CONTRACTION 617

Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0gconverges to p.

IfM.x;y/Dmaxfd.x;y/;d.x;Sx/;d.y;Sy/g in Theorem 1, Theorem 2, we ob-tain the following corollaries.

Corollary 3 ([2]). Let .X;d/ be a complete metric space, ˛ W X �X ! R be afunction. Let S WX !X be a mapping then suppose that the following holds:

(i) S is a generalized ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� 1;(iv) S is continuous;Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0g

converges to p.

Corollary 4 ([2]). Let .X;d/ be a complete metric space, ˛ W X �X ! R be afunction. Let S WX !X be a mapping then suppose that the following holds:

(i) S is a generalized ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� 1;(iv) if fxng is a sequence in X such that ˛.xn;xnC1/ � 1 for all n 2N[f0g and

xn! p 2 X as n!C1; then there exists a subsequencefxnkg of fxng such that

˛.xnk;p/� 1 for all k:

Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0gconverges to p.

Let .X;d/ be a metric space, and let ˛;� W X �X ! R be a function. A mapS;T W X ! X is called a pair of generalized rational ˛-Geraghty contraction typemappings if there exists ˇ 2˝ such that for all x;y 2X ,

˛.x;y/� �.x;y/) d.Sx;Ty/� ˇ .M.x;y//M.x;y/ (2.16)

where

M.x;y/Dmax�d.x;y/;

d.x;Sx/d.y;Ty/

1Cd.x;y/;d.x;Sx/d.y;Ty/

1Cd.Sx;Ty/

�:

Theorem 4. Let .X;d/ be a complete metric space. Let S is ˛�admissible map-pings with respect to � such that the following holds:

(i) .S;T / is a generalized rational ˛-Geraghty contraction type mapping;(ii) .S;T / is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� �.x0;Sx0/;(iv) S and T are continuous;Then .S;T / have common fixed point.

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618 MUHAMMAD ARSHAD AND AFTAB HUSSAIN

Proof. Let x1 inX be such that x1D Sx0 and x2D T x1. Continuing this process,we construct a sequence xn of points in X such that,

x2iC1 D Sx2i ; and x2iC2 D T x2iC1, wherei D 0;1;2; : : : : (2.17)

By assumption ˛.x0;x1/� �.x0;x1/ and the pair .S;T / is ˛-admissible with respectto �, we have; ˛.Sx0;T x1/ � �.Sx0;T x1/ from which we deduce that ˛.x1;x2/ ��.x1;x2/ which also implies that ˛.T x1;Sx2/ � �.T x1;Sx2/: Continuing in thisway we obtain ˛.xn;xnC1/� �.xn;xnC1/ for all n 2N[f0g:

d.x2iC1;x2iC2/ D d.Sx2i ;T x2iC1/� ˛.x2i ;x2iC1/d.Sx2i ;T x2iC1/

� ˇ .M.x2i ;x2iC1//M.x2i ;x2iC1/;

Therefore,d.x2iC1;x2iC2/� ˛.x2i ;x2iC1/d.Sx2i ;T x2iC1/ (2.18)

for all i 2N[f0g: Now

M.x2i ;x2iC1/Dmax�d.x2i ;x2iC1/;

d.x2i ;Sx2i /d.x2iC1;T x2iC1/

1Cd.x2i ;x2iC1/;d.x2i ;Sx2i /d.x2iC1;T x2iC1/

1Cd.Sx2i ;T x2iC1/

�Dmax

�d.x2i ;x2iC1/;

d.x2i ;x2iC1/d.x2iC1;x2iC2/

1Cd.x2i ;x2iC1/;d.x2i ;Sx2i /d.x2iC1;T x2iC1/

1Cd.x2iC1;x2iC2/

��max

˚d.x2i ;x2iC1/;d.x2iC1;x2iC2/

:

From the definition of ˇ, the case M.x2i ;x2iC1/D d.x2iC1;x2iC2/ is impossible.

d.x2iC1;x2iC2/� ˇ .M.x2i ;x2iC1//M.x2i ;x2iC1/

� ˇ .d.x2iC1;x2iC2//d.x2iC1;x2iC2/ < d.x2iC1;x2iC2/:

Which is a contradiction. Otherwise, in other case

d.x2iC1;x2iC2/� ˇ .M.x2i ;x2iC1//M.x2i ;x2iC1/

� ˇ .d.x2i ;x2iC1//d..x2i ;x2iC1/ < d.x2i ;x2iC1/:

This, implies that

d.xnC1;xnC2/ < d.xn;xnC1/; for all n 2N[f0g: (2.19)

Follows the similar lines of the Theorem 2. Hence p is common fixed point of S andT . �

Theorem 5. Let .X;d/ be a complete metric space and let .S;T / are ˛�admissiblemappings with respect to � such that the following holds:

(i) .S;T / is a generalized rational ˛-Geraghty contraction type mapping;(ii) .S;T / is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� �.x0;Sx0/;(iv) if fxng is a sequence in X such that ˛.xn;xnC1/ � �.xn;xnC1/ for all n 2

N[f0g and xn! p 2X as n!C1; then there exists a subsequencefxnkg of fxng

such that ˛.xnk;p/� �.xnk

;p/ for all k:Then S and T has common fixed point.

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FIXED POINT RESULTS FOR G-RATIONAL ˛-GERAGHTY CONTRACTION 619

Proof. Follows the similar line of the Theorem 3. �

IfM.x;y/Dmax�d.x;y/;

d.x;Sx/d.y;Sy/

1Cd.x;y/;d.x;Sx/d.y;Sy/

1Cd.Sx;Sy/

�and S D T in

the Theorem 4, Theorem 5 , we get the following corollaries.

Corollary 5. Let .X;d/ be a complete metric space and let S is ˛�admissiblemappings with respect to � such that the following holds:

(i) S is a generalized rational ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� �.x0;Sx0/;(iv) S is continuous;Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0g

converges to p.

Corollary 6. Let .X;d/ be a complete metric space and let S is ˛�admissiblemappings with respect to � such that the following holds:

(i) S is a generalized rational ˛-Geraghty contraction type mapping;(ii) S is triangular ˛-admissible;(iii) there exists x0 2X such that ˛.x0;Sx0/� �.x0;Sx0/;(iv) if fxng is a sequence in X such that ˛.xn;xnC1/ � �.xn;xnC1/ for all n 2

N[f0g and xn! p 2X as n!C1; then there exists a subsequencefxnkg of fxng

such that ˛.xnk;p/� �.xnk

;p/ for all k:Then S has a fixed point p 2 X , and S is a Picard operator, that is, fSnx0g

converges to p.

Example 2. Let X D f1;2;3g with metric

d.1;3/D d.3;1/D5

7d.1;1/D d.2;2/D d.3;3/D 0

d.1;2/D d.2;1/D 1; d.2;3/D d.3;2/D4

7

˛ .x;y/D

�1; if x;y 2X;0; otherwise

�:

Define the mappings S;T WX !X as follows:

Sx D 1 for each x 2X:

T .1/D T .3/D 1; T .2/D 3:

and ˇ W Œ0;C1/! Œ0;1�, then

˛.x;y/d.T x;Ty/� ˇ.M.x;y//M.x;y/:

Let x D 2 and y D 3 then condition (2.1) is not satisfied.

d .T .2/;T .3//D d.3;1/D5

7

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620 MUHAMMAD ARSHAD AND AFTAB HUSSAIN

M.x;y/Dmaxfd.2;3/;d.2;T .2//;d.3;T .3//g

Dmax�4

7;4

7;5

7

�D5

7

and˛.2;3/d .T .2/;T .3//— ˇ.M.x;y//M.x;y/:

If

M.x;y/Dmax�d.2;3/;

d.2;T .2//d.3;T .3//

1Cd.2;3/;d.2;T .2//d.3;T .3//

1Cd.T 2;T 3/

�Dmax

�4

7;20

77;20

84

�D4

7

Then the contractions does not holds.

˛.2;3/d .T .2/;T .3//— ˇ.M.x;y//M.x;y/:

We prove that Theorem 1 can be applied to S and T: Let x;y 2 X; clearly .S;T / is˛�admissible mapping such that ˛.x;y/ � 1: Let x;y 2 X and so that Sx;Ty 2 Xand ˛.Sx;Ty/D 1: Hence .S;T / is ˛-admissible. We show that condition .2:1/ ofTheorem 1 is satisfied. If x;y 2X then ˛.x;y/D 1; we have

˛.x;y/d.Sx;Ty/� ˇ.M.x;y//.M.x;y// :

where

M.x;y/Dmax�d.2;3/;

d.2;S.2//d.3;T .3//

1Cd.2;3/;d.2;S.2//d.3;T .3//

1Cd.S2;T 3/

�Dmax

�4

7;20

77;20

49

�D4

7

andd.S2;T 3/D d.1;1/D 0:

˛.x;y/d.Sx;Ty/� ˇ.M.x;y//.M.x;y// :

Hence all the hypothesis of the Theorem 1 is satisfied, So S;T have a common fixedpoint.

Remark 1. More detail, applications and examples see in [2] and references therein. Our results are more general than those in [2], [15] and improve several resultsexisting in the literature.

ACKNOWLEDGEMENT

The authors sincerely thank the learned referee for a careful reading and thoughtfulcomments. The present version of the paper owes much to the precise and kindremarks of anonymous referees.

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FIXED POINT RESULTS FOR G-RATIONAL ˛-GERAGHTY CONTRACTION 621

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Authors’ addresses

Muhammad ArshadInternational Islamic University, Department of Mathematics and Statistics, H-10, Islamabad, PakistanE-mail address: [email protected]

Aftab HussainInternational Islamic University, Department of Mathematics and Statistics, H-10, Islamabad, PakistanCurrent address: Khwaja Fareed University of Engineering & Information Technology, 64200,

Rahim Yar Khan, PakistanE-mail address: [email protected]