@ Appl. Gen. Topol. 23, no. 1 (2022), 213-223 doi:10.4995/agt.2022.11902 © AGT, UPV, 2022 Numerical reckoning fixed points via new faster iteration process Kifayat Ullah a,∗ , Junaid Ahmad b and Fida Muhammad Khan c a Department of Mathematical Sciences, University of Lakki Marwat, Lakki Marwat - 28420, Pakistan (kifayatmath@yahoo.com) b Department of Mathematics, International Islamic University, Islamabad - 44000, Pakistan (ahmadjunaid436@gmail.com) c Department of Mathematics, University of Science and Technology, Bannu - 28100, Pak- istan (fidamuhammad809@gmail.com) Communicated by M. Abbas Abstract In this paper, we propose a new iteration process which is faster than the leading; S [J. Nonlinear Convex Anal. 8, no. 1 (2007), 61–79], Thakur et al. [App. Math. Comp. 275 (2016), 147–155] and M [Filomat 32, no. 1 (2018), 187–196] iterations for numerical reckoning fixed points. Using this new iteration process, some fixed point convergence results for generalized α-nonexpansive mappings in the setting of uniformly convex Banach spaces are proved. At the end of paper, we offer a numerical example to compare the rate of convergence of the proposed iteration process with the leading iteration processes. 2020 MSC: 47H09; 47H10. Keywords: generalized α-nonexpansive mappings; uniformly convex Banach space; iteration process; weak convergence; strong convergence. 1. Introduction Throughout this paper, we will denote the set of natural numbers by N. Let X be a Banach space and M be a nonempty subset of X. A mapping Received 27 May 2019 – Accepted 24 November 2021 http://dx.doi.org/10.4995/agt.2022.11902 https://orcid.org/0000-0002-6991-4287 K. Ullah, J. Ahmad and F. M. Khan T : M → M is said to nonexpansive if ||Tx−Ty|| ≤ ||x−y||, for all x,y ∈ M. An element p ∈ M is said to be a fixed point of T if p = T(p). From now on, we will denote the set of all fixed points of T by F(T). A mapping T : M → M is said to be a quasi-nonexpansive mapping if F(T) 6= ∅ and ||T(x) −T(p)|| ≤ ||x−p|| for all x ∈ M and p ∈ F(T). It is well-known that F(T) is nonempty in the case when X is uniformly convex, T is nonexpansive and M is closed, bounded and convex; see [6, 7, 10]. A number of generaliza- tions of nonexpansive mappings have been considered by some researchers in recent years. Suzuki [17] introduced a new class of mappings known as Suzuki generalized nonexpansive mappings which is a condition on mappings called condition (C) and obtained some convergence and existence results for such mappings. Note that, a mapping T : M → M is said to satisfy condition (C) if 1 2 ||x−Tx|| ≤ ||x−y|| implies ||Tx−Ty|| ≤ ||x−y||, for each x,y ∈ M. Aoyama and Kohsaka [4] introduced the class of α-nonexpansive mappings in the framework of Banach spaces and obtained some fixed point results for such mappings. A mapping T : M → M is said to be α-nonexpansive if there exists a real number α ∈ [0, 1) such that for all x,y ∈ M, ||Tx−Ty||2 ≤ α||Tx−y||2 + α||x−Ty||2 + (1 − 2α)||x−y||2. Ariza-Puiz et al. [5] proved that the concept of α-nonexpansive is trivial for α < 0. It is obvious that every nonexpansive mapping is 0-nonexpansive and also every α-nonexpansive mapping with F(T) 6= ∅ is a quasi-nonexpansive. Note that, in general condition (C) and α-nonexpansive mappings are not con- tinuous (see [17] and [14] ). Recently, Pant and Shukla [14] introduced an interesting class of generalized nonexpansive mappings in Banach spaces known as generalized α-nonexpansive mappings which contains the class of Suzuki generalized nonexpansive map- pings. A mapping T : M → M is said to generalized α-nonexpansive if there exists a real number α ∈ [0, 1) such that for each x,y ∈ M, 1 2 ||x−Tx|| ≤ ||x−y|| ⇒ ||Tx−Ty|| ≤ α||Tx−y||+α||Ty−x||+(1−2α)||x−y||. Once the existence result of a fixed point for a mapping is established, an algorithm to find the value of the fixed point is desirable. The famous Banach contraction mapping principle uses Picard iteration xn+1 = Txn for approx- imation of fixed point. Some other well-known iterations are the Mann [11], Ishikawa [9], S [3], Picard-S [8], Noor [12], Abbas [1], Thakur et al. [19] and so on. Speed of convergence plays an important role for an iteration process to be preferred on another iteration process. Rhoades [15] mentioned that the Mann iteration process for a decreasing function converges faster than the Ishikawa iteration process and for an increasing function the Ishikawa iteration process is better than the Mann iteration process. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 214 Numerical reckoning fixed points via new faster iteration process The well-known Mann [11] and Ishikawa [9] iteration schemes are respec- tively defined as: (1.1) { x1 ∈ M, xn+1 = (1 −αn)xn + αnTxn,n ∈ N, where αn ∈ (0, 1). (1.2)   x1 ∈ M, yn = (1 −βn)xn + βnTxn, xn+1 = (1 −αn)xn + αnTyn,n ∈ N, where αn,βn ∈ (0, 1). In 2007, Agarwal et al. [3] introduced the following iteration process known as S iteration: (1.3)   x1 ∈ M, yn = (1 −βn)xn + βnTxn, xn+1 = (1 −αn)Txn + αnTyn,n ∈ N, where αn,βn ∈ (0, 1). They proved that the rate of convergence of iteration process (1.3) is same to the Picard iteration xn+1 = Txn and faster than the Mann [11] iteration process in the class of contraction mappings. In 2016, Thakur et al. [19] introduced the following iteration scheme: (1.4)   x1 ∈ M, zn = (1 −βn)xn + βnTxn, yn = T ((1 −αn)xn + αnzn) , xn+1 = Tyn,n ∈ N, where αn,βn ∈ (0, 1). With the help of a numerical example, they proved that (1.4) is faster than the Picard, Mann [11], Ishikawa [9], S [3], Noor [12] and Abbas [1] iteration processes in the class of Suzuki generalized nonexpansive mappings. Recently in 2018, Ullah and Arshad [20] used a new iteration process known as M iteration: (1.5)   x1 ∈ M, zn = (1 −αn)xn + αnTxn, yn = Tzn, xn+1 = Tyn,n ∈ N, where αn ∈ (0, 1). With the help of a numerical example, they proved that (1.5) is faster than S [3], Picard-S [8] and Thakur et al. [19] iteration processes for Suzuki generalized nonexpansive mappings. Problem 1.1. Is it possible to develop an iteration process whose rate of con- vergence is even faster than the iteration process (1.5) ? © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 215 K. Ullah, J. Ahmad and F. M. Khan As an answer, we introduce the following new iteration called KF iteration scheme: (1.6)   x1 ∈ M, zn = T((1 −βn)xn + βnTxn), yn = Tzn, xn+1 = T((1 −αn)Txn + αnTyn),n ∈ N, where αn,βn ∈ (0, 1). With the help of numerical example, we compare the rate of convergence of iteration (1.6) with the leading S (1.3), Thakur et al. (1.4) and M (1.5) iteration. 2. Preliminaries In this section, we give some preliminaries. Let X be a Banach space and M be a nonempty closed convex subset of X. Let {xn} be a bounded sequence in M. For x ∈ X, set r(x,{xn}) = lim sup n→∞ ||x−xn||. The asymptotic radius of {xn} relative to M is given by r(M,{xn}) = inf{r(x,{xn}) : x ∈ M}. The asymptotic center of {xn} relative to M is the set A(M,{xn}) = {x ∈ M : r(x,{xn}) = r(M,{xn})}. It is well-known that in a uniformly convex Banach space setting, A(M,xn) consists of exactly one point. Also, A(M,xn) is nonempty and convex when M is weakly compact and convex (see, [18] and [2]). A Banach space X is said to uniformly convex if for all ε > 0, there is a λ > 0 such that, for x,y ∈ X with ||x|| ≤ 1, ||y|| ≤ 1 and ||x − y|| ≤ ε, ||x + y|| ≤ 2(1 − λ) holds. Note that, a Banach space X is said to have Opial’s property [13] if for each sequence {xn} in X which weakly converges to x ∈ X and for every y ∈ X, it follows the following lim sup n→∞ ||xn −x|| < lim sup n→∞ ||xn −y||. Examples of Banach spaces satisfying this condition are Hilbert spaces and all lp spaces (1 < p < ∞). We now list some basic facts about generalized α-nonexpansive mappings, which can be found in [14]. Proposition 2.1. Let X be a Banach space, M be a nonempty subset of X and T : M → M be a mapping. (i) If T is a Suzuki generalized nonexpansive mapping, then T is a gener- alized α-nonexpansive mapping. (ii) If T is a generalized α-nonexpansive mapping and has a fixed point, then T is a quasi-nonexpansive mapping. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 216 Numerical reckoning fixed points via new faster iteration process (iii) If T is a generalized α-nonexpansive mapping. Then F(T) is closed. Moreover, if X is strictly convex and M is convex, then F(T) is also convex. (iv) If T is a generalized α-nonexpansive mapping. Then for each x,y ∈ M, ||x−Ty|| ≤ ( 3 + α 1 −α ) ||x−Tx|| + ||x−y||. (v) If X has Opial property, T is generalized α-nonexpansive, {xn} con- verges weakly to a point v and limn→∞ ||Txn−xn|| = 0, then v ∈ F(T). Lemma 2.2 ([16]). Let X be a uniformly convex Banach space and 0 < p ≤ αn ≤ q < 1 for every n ∈ N. If {xn} and {yn} are two sequences in X such that lim supn→∞ ||xn|| ≤ t, lim supn→∞ ||yn|| ≤ t and limn→∞ ||αnxn + (1 − αn)yn|| = t for some t ≥ 0 then, limn→∞ ||xn −yn|| = 0. 3. Main Results We open this section with the following important lemma. Lemma 3.1. Let M be a nonempty closed convex subset of a Banach space X and T : M → M be a generalized α-nonexpansive mapping with F(T) 6= ∅. Let {xn} be a sequence generated by (1.6), then limn→∞ ||xn − p|| exists for each p ∈ F(T). Proof. Let p ∈ F(T). By Proposition 2.1 part (ii), we have ||zn −p|| = ||T((1 −βn)xn + βnTxn) −p|| ≤ ||(1 −βn)xn + βnTxn −p|| ≤ (1 −βn)||xn −p|| + βn||Txn −p|| ≤ (1 −βn)||xn −p|| + βn||xn −p|| ≤ ||xn −p||, and ||yn −p|| = ||Tzn −p|| ≤ ||zn −p||. They imply that, ||xn+1 −p|| = ||T((1 −αn)Txn + αnTyn) −p|| ≤ ||(1 −αn)Txn + αnTyn −p|| ≤ (1 −αn)||Txn −p|| + αn||Tyn −p|| ≤ (1 −αn)||xn −p|| + αn||yn −p|| ≤ (1 −αn)||xn −p|| + αn||zn −p|| ≤ (1 −αn)||xn −p|| + αn||xn −p|| ≤ ||xn −p||. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 217 K. Ullah, J. Ahmad and F. M. Khan Thus {||xn−p||} is bounded and nonincreasing, which implies that limn→∞ ||xn− p|| exists for all p ∈ F(T). � The following theorem is necessary for the next results. Theorem 3.2. Let M be a nonempty closed convex subset of a uniformly con- vex Banach space X and T : M → M a generalized α-nonexpansive mapping. Let {xn} be a sequence generated by (1.6). Then, F(T) 6= ∅ if and only if {xn} is bounded and limn→∞ ||Txn −xn|| = 0. Proof. Suppose that F(T) 6= ∅ and p ∈ F(T). Then, by Lemma 3.1, limn→∞ ||xn− p|| exists and {xn} is bounded. Put (3.1) lim n→∞ ||xn −p|| = t. In view of the proof of Lemma 3.1 together with (3.1), we have (3.2) lim sup n→∞ ||zn −p|| ≤ lim sup n→∞ ||xn −p|| = t. By Proposition 2.1 part (ii), we have (3.3) lim sup n→∞ ||Txn −p|| ≤ lim sup n→∞ ||xn −p|| = t. Again by the proof of Lemma 3.1, we have ||xn+1 −p|| ≤ (1 −αn)||xn −p|| + αn||zn −p||. It follows that, ||xn+1 −p||− ||xn −p|| ≤ ||xn+1 −p||− ||xn −p|| αn ≤ ||zn −p||− ||xn −p||. So, we can get ||xn+1 −p|| ≤ ||zn −p|| and from (3.1), we have (3.4) t ≤ lim inf n→∞ ||zn −p||. From (3.2) and (3.4), we obtain (3.5) t = lim n→∞ ||zn −p||. From (3.1) and (3.5), we have t = lim n→∞ ||zn −p|| = lim n→∞ ||T((1 −βn)xn + βnTxn) −p|| ≤ lim n→∞ ||(1 −βn)xn + βnTxn −p|| = lim n→∞ ||(1 −βn)(xn −p) + βn(Txn −p)|| ≤ lim n→∞ (1 −βn)||xn −p|| + lim n→∞ βn||Txn −p|| ≤ lim n→∞ (1 −βn)||xn −p|| + lim n→∞ βn||xn −p|| ≤ t. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 218 Numerical reckoning fixed points via new faster iteration process Hence, (3.6) t = lim n→∞ ||(1 −βn)(xn −p) + βn(Txn −p)||. Now from (3.1), (3.3) and (3.6) together with Lemma 2.2, we obtain lim n→∞ ||Txn −xn|| = 0. Conversely, we assume that {xn} is bounded and limn→∞ ||Txn−xn|| = 0. Let p ∈ A(M,{xn}). By proposition 2.1 part (iv), we have r(Tp,{xn}) = lim sup n→∞ ||xn −Tp|| ≤ ( 3 + α 1 −α ) lim sup n→∞ ||Txn −xn|| + lim sup n→∞ ||xn −p|| = lim sup n→∞ ||xn −p|| = r(p,{xn}). Hence, we conclude that Tp ∈ A(M,{xn}. Since X is uniformly convex, A(M,{xn}) consist of a unique element. Thus, we have p = T(p). � First we prove our weak convergence result. Theorem 3.3. Let X be a uniformly Banach space with Opial property, M a nonempty closed convex subset of X and T : M → M be generalized α- nonexpansive mapping with F(T) 6= ∅. Then, {xn} generated by (1.6) con- verges weakly to an element of F(T). Proof. By Theorem 3.2, {xn} is bounded and limn→∞ ||Txn −xn|| = 0. Since X is uniformly convex, X is reflexive. So, a subsequence {xni} of {xn} exists such that {xni} converges weakly to some v1 ∈ M. By Proposition 2.1 part (v), we have v1 ∈ F(T). It is sufficient to show that {xn} converges weakly to v1. In fact, if {xn} does not converges weakly to v1. Then, there exists a subsequence {xnj} of {xn} and v2 ∈ M such that {xnj} converges weakly to v2 and v2 6= v1. Again by Proposition 2.1 part (v), v2 ∈ F(T). By Lemma 3.1 together with Opial property, we have lim n→∞ ||xn −v1|| = lim i→∞ ||xni −v1|| < lim i→∞ ||xni −v2|| = lim n→∞ ||xn −v2|| = lim j→∞ ||xnj −v2|| < lim j→∞ ||xnj −v1|| = lim n→∞ ||xn −v1||. This is a contradiction, so, v1 = v2. Thus, {xn} converges weakly to v1 ∈ F(T). � © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 219 K. Ullah, J. Ahmad and F. M. Khan We now prove our strong convergence result. Theorem 3.4. Let M be a nonempty closed convex subset of a uniformly con- vex Banach space X and T : M → M be a generalized α-nonexpansive map- ping. If F(T) 6= ∅ and lim infn→∞dist(xn,F(T)) = 0 (where dist(x,F(T)) = inf{||x−p|| : p ∈ F(T)}). Then, {xn} generated by (1.6) converges strongly to an element of F(T). Proof. By Lemma 3.1, limn→∞ ||xn − p|| exists, for each p ∈ F(T). So, limn→∞dist(xn,F(T)) exists, thus lim n→∞ dist(xn,F(T)) = 0. Therefore, there exists a subsequence {xnk} of {xn} and {vk} in FT such that ||xnk − vk|| ≤ 1 2k for each k ∈ N. By the proof of Lemma 3.1, {xn} is nonin- creasing, so ||xnk+1 −vk|| ≤ ||xnk −vk|| ≤ 1 2k . Therefore, ||vk+1 −vk|| ≤ ||vk+1 −xnk+1|| + ||xnk+1 −vk|| ≤ 1 2k+1 + 1 2k ≤ 1 2k−1 → 0, as k →∞. Hence, {vk} is a Cauchy sequence in F(T) and so it converges to some p. Since, by Proposition 2.1 part (iii), F(T) is closed, we have p ∈ F(T). By Lemma 3.1, limn→∞ ||xn −p|| exists, hence {xn} converges strongly to p ∈ F(T). � 4. example We compare rate of convergence of our new KF iteration (1.6) with leading S (1.3), M (1.5) Thakur et al. (1.4) in slightly general setting using Exam- ple 4.1, in which T is generalized α-nonexpansive but not Suzuki generalized nonexpansive. Example 4.1. Let M = [0,∞) with absolute valued norm. Define a mapping T : M → M by Tx = { 0 if x ∈ [ 0, 1 5000 ) x 2 if x ∈ [ 1 5000 ,∞ ) . Choose x = 1 8000 and y = 1 5000 . We see that, 1 2 |x − Tx| < |x − y| but |Tx − Ty| > |x − y|. Thus, T does not satisfy condition (C) and so T is not Suzuki generalized nonexpansive. On the other hand, T is a generalized α-nonexpansive mapping. In fact, for α = 1 3 , we have: Case I: When x,y ∈ [ 0, 1 5000 ) , then clearly 1 3 |Tx−y| + 1 3 |x−Ty| + 1 3 |x−y| ≥ 0 = |Tx−Ty|. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 220 Numerical reckoning fixed points via new faster iteration process Case II: When x ∈ [ 1 5000 ,∞ ) and y ∈ [ 0, 1 5000 ) , we have 1 3 |Tx−y| + 1 3 |x−Ty| + 1 3 |x−y| = 1 3 ∣∣∣x 2 −y ∣∣∣ + 1 3 |x− 0| + 1 3 |x−y| ≥ 1 3 ∣∣∣(x 2 −y ) − (x−y) ∣∣∣ + 1 3 |x| = 1 3 ∣∣∣x 2 ∣∣∣ + 1 3 |x| ≥ 1 3 ∣∣∣x 2 + x ∣∣∣ = 1 2 |x| = |Tx−Ty|. Case III: When x,y ∈ [ 1 5000 ,∞), we have 1 3 |Tx−y| + 1 3 |x−Ty| + 1 3 |x−y| = 1 3 ∣∣∣x 2 −y ∣∣∣ + 1 3 ∣∣∣x− y 2 ∣∣∣ + 1 3 |x−y| ≥ 1 3 ∣∣∣(x 2 −y ) + ( x− y 2 )∣∣∣ + 1 3 |x−y| = 1 2 |x−y| + 1 3 |x−y| ≥ 1 2 |x−y| = |Tx−Ty|. Hence, T is a generalized α-nonexpansive mapping with F(T) = {0}. Take αn = 0.70 and βn = 0.65. The iterative values for x1 = 10 are given in Table 1. Figure 1 shows the convergence behaviors of different iterative schemes. Clearly the new KF iteration process is moving fast to the fixed point of T as compared to other iteration processes. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 221 K. Ullah, J. Ahmad and F. M. Khan Table 1. Sequences generated by KF (1.6), M (1.5), Thakur et al. (1.4) and S (1.3) iteration schemes for mapping T of Example 4.1. KF (1.6) M (1.5) Thakur et al. (1.4) S (1.3) x1 10 10 10 10 x2 1.0453120000 1.62500000000 1.9312500000 3.8625000000 x3 0.1092678222 0.26406250000 0.3729726562 1.4918906250 x4 0.0114219020 0.04291015625 0.0720303442 0.5762427539 x5 0.0011939456 0.00697290039 0.0139108602 0.2225737636 x6 0.0001248046 0.00113309631 0.0026865348 0.0859691162 x7 0 0.00018412815 0.0005188370 0.0332055711 x8 0 0 0.0001002004 0.0128256518 x9 0 0 0 0.0049539080 x10 0 0 0 0.0019134469 x11 0 0 0 0.0007390688 x12 0 0 0 0.0002854653 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 0 2 4 6 8 10 12 14 0 1 2 3 4 5 Number of iteration V a lu e o f x n KF M Thakur et al. S Figure 1. Convergence behaviors of KF, M, Thakur et al. and S iteration processes to the fixed point of the mapping defined in Example 4.1 where x1 = 10. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 222 Numerical reckoning fixed points via new faster iteration process References [1] M. Abbas and T. Nazir, A new faster iteration process applied to constrained minimiza- tion and feasibility problems, Mat. Vesnik 66, no. 2 (2014) 223–234. [2] R. P. Agarwal, D. O’Regan and D. S. Sahu, Fixed Point Theory for Lipschitzian-type Mappings with Applications Series: Topological Fixed Point Theory and Its Applica- tions, vol. 6. Springer, New York (2009). [3] R. P. Agarwal, D. O’Regan and D. R. Sahu, Iterative construction of fixed points of nearly asymptotically nonexpansive mappings, J. Nonlinear Convex Anal. 8, no. 1 (2007), 61–79. [4] K. Aoyama and F. Kohsaka, Fixed point theorem for α-nonexpansive mappings in Ba- nach spaces, Nonlinear Anal. 74 (2011), 4387–4391. [5] D. Ariza-Ruiz, C. Hermandez Linares, E. Llorens-Fuster and E. Moreno-Galvez, On α-nonexpansive mappings in Banach spaces, Carpath. J. Math. 32 (2016), 13–28. [6] F. E. Browder, Nonexpansive nonlinear operators in a Banach space, Proc. Nat. Acad. Sci. USA. 54 (1965), 1041–1044. [7] D. Gohde, Zum Prinzip der Kontraktiven Abbildung, Math. Nachr. 30 (1965), 251–258. [8] F. Gursoy and V. Karakaya, A Picard-S hybrid type iteration method for solving a differential equation with retarted argument, (2014) arXiv:1403.2546v2. [9] S. Ishikawa, Fixed points by a new iteration method, Proc. Am. Math. Soc. 44 (1974), 147–150. [10] W. A. Kirk, A fixed point theorem for mappings which do not increase distance, Am. Math. Monthly 72 (1965), 1004–1006. [11] W. R. Mann, Mean value methods in iterations, Proc. Amer. Math. Soc. 4 (1953), 506–510. [12] M. A. Noor, New approximation schemes for general variational inequalities, J. Math. Anal. Appl. 251, no. 1 (2000), 217–229. [13] Z. Opial, Weak and strong convergence of the sequence of successive approximations for nonexpansive mappings, Bull. Am. Math. Soc. 73 (1967), 591–597. [14] D. Pant and R. Shukla, Approximating fixed points of generalized α-nonexpansive map- pings in Banach spaces, Numer. Funct. Anal. Optim. 38, no. 2 (2017), 248–266. [15] B. E. Rhoades, Some fixed point iteration procedures, Int. J. Math. Math. Sci. 14 (1991), 1–16. [16] J. Schu, Weak and strong convergence to fixed points of asymptotically nonexpansive mappings, Bull. Austral. Math. Soc. 43 (1991), 153-159. [17] T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonex- pansive mappings, J. Math. Anal. Appl. 340 (2008), 1088–1095. [18] W. Takahashi, Nonlinear Functional Analysis. Yokohoma Publishers, Yokohoma (2000). [19] B. S. Thakur, D. Thakur and M. Postolache, A new iterative scheme for numerical reck- oning fixed points of Suzuki’s generalized nonexpansive mappings, App. Math. Comp. 275 (2016), 147–155. [20] K. Ullah and M. Arshad, Numerical reckoning fixed points for Suzuki’s Generalized nonexpansive mappings via new iteration process, Filomat 32, no. 1 (2018), 187–196. [21] H. H. Wicke and J.M. Worrell, Jr., Open continuous mappings of spaces having bases of countable order, Duke Math. J. 34 (1967), 255–271. © AGT, UPV, 2022 Appl. Gen. Topol. 23, no. 1 223