#### Abstract

This paper is aimed at establishing some unique common fixed point theorems in complex-valued -metric space under the rational type contraction conditions for three self-mappings in which the one self-map is continuous. A continuous self-map is commutable with the other two self-mappings. Our results are verified by some suitable examples. Ultimately, our results have been utilized to prove the existing solution to the two Urysohn integral type equations. This application illustrates how complex-valued -metric space can be used in other types of integral operators.

#### 1. Introduction

In 1922, Banach [1] proved a fixed point theorem (FP-theorem), which is stated as the following: “a single-valued contractive type mapping on a complete metric space has a unique fixed point.” After the publication of the Banach FP-theorem, many researchers have contributed their ideas to the theory of FP. Chandok [2, 3], Jungck and Rhoades [4], and Al-Shami and Abo-Tabl [5, 6] proved different contractive types of FPs and a-fixed soft point results in the context of metric spaces.

Bakhtin [7] introduced the idea of -metric space, while Czerwik [8] proved some fixed point results for nonlinear set-valued contractive type mappings in -metric spaces. Suzuki in [9] proved basic inequality and some FP-theorems. Jain and Kaur [10] presented a new class of functions to define new contractive maps and established FP-results for these maps. They also extended some results in the framework of -metric-like spaces. They presented examples and established the application of their main results. They also presented some open problems. Petrusel et al. [11] considered coupled FP-problems for single-valued operators satisfying contraction in said space. They discussed uniqueness, data dependence, and shadowing-property of coupled FP-problem and also established an application for main results. Ameer et al. [12], Boriceanu [13, 14], Bota et al. [15], Czerwik et al. [16, 17], Hussain and Shah [18], Karapinar et al. [19], and Samreen et al. [20] established different contractive type FP and common FP (CFP) results in the context of -metric spaces.

In 2011, the concept of complex-valued metric space was given by Azam et al. [21], and they proved some CFP-theorems for self-mappings. The notion of said space was proposed by Rouzkard and Imdad [22] which generalizes the results of Azam et al. [21] and established some CFP-results. Abbas et al. [23] presented some generalized CFP-results by using cocyclic mappings in complex-valued metric space. They provided examples to indicate the authenticity of his expressions. Sarwar and Zada [24] used the ideas of and properties and proved FP-results for six self-mappings. They showed the existence of their results by establishing some examples. Abbas et al. [25], Nashine et al. [26], Mohanta and Maitra [27], Sintunavarat and Kumam [28], and Verma and Pathak [29] proved some results in the context of complex-valued metric space.

In 2013, Rao et al. [30] introduced the notion of complex-valued -metric space. Mukheimer et al. [31] established CFP-results on said space by extending and generalizing the results of [30, 31]. In [32], Chantakun et al. extend the work of Dubey et al. [33] by introducing sufficient conditions to prove some CFP-results in complex-valued -metric space. Yadav et al. [34] used compatible and weakly compatible maps to find CFP-results. They proved the validity of the results by providing some examples and establishing an application. Berrah et al. [35], Hasana [36], Mehmood et al. [37], and Mukheimer [38] established some FP and CFP theorems in complex-valued -metric spaces.

In this paper, we provide some extended and effective CFP-results for commuting three self-maps on complex-valued -metric spaces. To verify the validity of our work, we present some illustrative examples in the main section. Further, our results have been utilized to prove the existing solution to the two Urysohn integral type equations. This application is also illustrative of how complex-valued -metric space can be used in other integral type operators. This paper is organized as follows: In Section 2, we present the preliminary concepts. In Section 3, we establish some extended and modified CFP-results for commuting self-maps in complex-valued -metric space under the generalized rational type conditions. We also provide authentic examples to indicate the effectiveness of these results. In Section 4, we present an application of the two UITEs to support our main work. Finally, in Section 5, we discuss the conclusion.

#### 2. Preliminaries

Let be the set of all complex numbers and . Define as , iff and , where denotes the real part and denotes the imaginary part of a complex number. Accordingly, , if any one of the following conditions holds:

and

and

and

and

Know that if and one of (), (), and () is satisfied.

*Remark 1 (see [31]). *We can easily check the following:
(i)If and , (ii)(iii) and

*Definition 2 (see [8]). *Let be a nonempty set and a given real number. A mapping *is* called a *-*metric on if the following conditions are satisfied:

if and only if

,

for all . Then, is called a -metric space.

*Definition 3 (see [30]). *Let be a nonempty set and a given real number. A mapping *is* called a complex-valued *-*metric on if the following conditions are satisfied:

and if and only if

,

for all . Then, is called a complex-valued -metric space.

*Example 4. *Let . Define the mapping *by*, for all .

Then, is a complex-valued -metric space with .

*Definition 5 (see [30, 31]). *Let be a complex-valued *-*metric space and a sequence in and . Then,
(1) is said to converge to if for every there exists such that , . We denote this by or as (2)if for every there exists such that for all , , then is called a Cauchy sequence(3)if every Cauchy sequence is convergent, then is called a complete complex-valued -metric space

Lemma 6 (see [30, 31]). *Let be a complex-valued -metric space and let be a sequence in . Then, converges to iff as .*

Lemma 7 (see [30, 31]). *Let be a complex-valued -metric space and let be a sequence in . Then, is a Cauchy sequence iff as .*

*Definition 8 (see [39]). *Let be a complex-valued *-*metric space. The self-mappings and are said to be commuting if for all .

#### 3. Main Result

In this section, we prove some CFP theorems in complex-valued -metric space under the generalized rational type contraction conditions for three self-mappings in which one is continuous. We present some examples for the validation of our work.

Theorem 9. *Let be a complete complex-valued -metric space and be three self-maps satisfying
for all , such that and . If is continuous and , are commutable pairs, then , and have a unique CFP in .*

*Proof. *Fix , and define a sequence sequences in such that

Now, by using (1),

This implies that

After simplification, we get that

This implies that

After simplification, we get that

Now, from (8) and (5) and by induction, we have that

So, for with ,

Therefore, the sequence is Cauchy. Since is complete, there exists such that , as , or , and from (2), we have

As is continuous, so

Since, and are commutable pairs, therefore, from (12), we have that

Now, we have to show that , so by putting and , in (1),

This implies that

Taking and using (11), (12), and (13), we get that

After simplification, we get that

Since , hence, we get that

Next, we have to show that , by the view of (1),

This implies that

Now, again applying on both sides and by using (11) and (18), we have that

This implies that . Hence,

Now, we have to show that , by using (1),

This implies that

Taking and using (11) and (18), we get

This implies that . Hence,

Thus, from (18), (22), and (26), we find that is a CFP of , and , i.e.,

Uniqueness: suppose that is another CFP of , and such that

Then, from (1), we have that

This implies that . Since . Hence, prove that , and have a unique CFP in .

If we put in Theorem 9, we get the following corollary.

Corollary 10. *Let be a complete complex-valued -metric space and be three self-maps satisfying
*

*for all , such that and . If is continuous and , are commutable pairs, then , and have a unique CFP in .*

If we put in Theorem 9, we can get the following corollary.

Corollary 11. *Let be a complete complex-valued -metric space and be three self-maps satisfying:
*

*for all , and . If is continuous and , are commutable pairs, then , and have a unique CFP in .*

Theorem 12. *Let be a complete complex-valued -metric space and be three self-maps satisfying
*