渐近非扩展映象的多步迭代

建立了渐近非扩展映象族的多步迭代格式的几个强收敛结果，所得结果扩展并改进了Xu和Noor等人的最新结果．     

一致凸Banach空间非扩张映象的修正Ishikawa迭代序列的强收敛

在一致凸Banach空间上，研究了半紧的非扩张压缩映象的修正Ishikawasa三重迭代序列的强收敛问题，建立并证明了若干强收敛定理，推广了Mann和Ishikawa的迭代方法，改进和发展了Xu和贾如鹏等作者的主要结果．     

非扩张映象对公共不动点的迭代逼近

对非扩张映象对引入了修改的Mann迭代格式，并证明了在一致光滑Banach空间中强收敛到其公共不动点，改进并推广了Tae—Hwa Kim and Hong—Kun Xu在2005年的结果．     

凸度量空间中拟压缩映象具误差的Ishikawa型迭代序列的收敛性

对凸度量空间中非线性拟压缩映象具误差的Ishikawa型迭代序列的收敛性问题证明了几个新的收敛性定理,结果不仅改进和推广了L.B.Ciric,Q.H.Liu,H.E.Rhoades,H.K.Xu等人的相应结果,而且对Rhoades-Naimplally-Singh所提出的公开问题,在凸度量空间的框架下给出了肯定的答复.     

有限族严格伪压缩映象具误差的隐迭代序列的强收敛性

在适当的条件下,证明了有限族严格伪压缩映象具误差的隐迭代序列强收敛于其公共不动点. 所得结果改进了Osilike 与 Xu, Ori 的相应结果.     

Banach空间中Lipschitz伪压缩半群公共不点的强收敛定理

在Banach空间的框架下,建立了几个关于Lipschitz伪压缩半群的隐迭代程序的弱收敛定理.所得结果改进和推广了Zhou,Chen等,Xu等及 Osilike 等人的最新结果.     

一般Banach空间中渐近非扩张型半群的不动点定理

该文首先在一般Banach空间中对渐近非扩张型半群证明了两个不动点存在定理,并由此给出了渐近非扩张型半群Mann型迭代序列的强收敛定理.该文的主要结果将Suzuki和Takahashi的相应结果推广到non-Lipschitzian半群情形.     

Hilbert空间中求解分裂可行问题CQ算法的强收敛性

在Hilbert空间中,为了研究分裂可行问题迭代算法的强收敛性,提出了一种新的CQ算法.首先利用CQ算法构造了一个改进的Halpern迭代序列； 然后通过把分裂可行问题转化为算子不动点， 在较弱的条件下， 证明了该序列强收敛到分裂可行问题的一个解. 推广了Wang和Xu的有关结果.     

含参广义集值强向量平衡问题的稳定性

本文借助集合极限的性质和弱f-性假设证明了含参广义集值强向量平衡问题解集映射的下半连续性,其方法不同于最近文献(Zhao,2016和Meng,2018).此外,建立了含参广义集值强向量平衡问题解集连通性的充分条件,并举例验证了所得结果的正确性.本文得结果推广和改进了已有文献(Gong,2008,Xu,2009,Chen,2010,Xu,2013和Zhao,2013)中相应结果.     

关于Romanoff常数及其推广问题

1934年,Romanoff证明了：可表为一个素数和一个2的方幂之和的大奇数在全体正整数中具有正密度．本文证明了此密度大于0．09322,从而改进了该问题的已有结果0．0868．作为此问题的推广,本文还建立了一个类似的数值结果：可表为两个素数的平方和两个2的方幂之和的大偶数具有正密度．     

Fixed point theory for generalized contractions in cone metric spaces

In this paper, we prove some fixed point theorems for generalized contractions in cone metric spaces. Our theorems extend some results of Suzuki (2008) [T. Suzuki, A generalized Banach contraction principle that characterizes metric completeness, Proc Amer Math Soc 136(5) (2008), 1861-1869] and Kikkawa and Suzuki (2008) [M. Kikkawa and T. Suzuki, Three fixed point theorems for generalized contractions with constants in complete metric spaces, Nonlinear Anal 69(9) (2008), 2942-2949].     

On quasi-contraction mappings of Ćirić and Fisher type via ω-distance

Kada, Suzuki, and Takahashi introduced and studies the concept of ω- distance in fixed point theory. In this paper, we generalize and unify ?iri?’ and Fisher fixed points results for quasi-contractions on metric space to ω-distance on complete metric spaces. We also extend some results of Kada, Suzuki and Takahashi, and Suzuki. Our methods of proofs are new and even simpler than the corresponding methods in metric spaces.     

Edelstein's method and fixed point theorems for some generalized nonexpansive mappings

A new condition for mappings, called condition (C), which is more general than nonexpansiveness, was recently introduced by Suzuki [T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mappings, J. Math. Anal. Appl. 340 (2008) 1088-1095]. Following the idea of Kirk and Massa Theorem in [W.A. Kirk, S. Massa, Remarks on asymptotic and Chebyshev centers, Houston J. Math. 16 (1990) 364-375], we prove a fixed point theorem for mappings with condition (C) on a Banach space such that its asymptotic center in a bounded closed and convex subset of each bounded sequence is nonempty and compact. This covers a result obtained by Suzuki [T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mappings, J. Math. Anal. Appl. 340 (2008) 1088-1095]. We also present fixed point theorems for this class of mappings defined on weakly compact convex subsets of Banach spaces satisfying property (D). Consequently, we extend the results in [T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mappings, J. Math. Anal. Appl. 340 (2008) 1088-1095] to many other Banach spaces.     

Fixed points of asymptotic pointwise contractions in modular spaces

Kirk and Xu introduced the concept of asymptotic pointwise contractions. In this paper, we investigate these kinds of mappings in modular spaces. Moreover, the fixed point theorem for asymptotic pointwise nonexpansive mappings in modular spaces is also studied. The results of this paper improve and extend the results of Razani et al. [A. Razani, E. Nabizadeh, M. Beyg Mohamadi, S. Homaei Pour, Fixed points of nonlinear and asymptotic contractions in the modular spaces, Abstract and Applied Analysis, 2007 (2007)], and Kirk and Xu [W. A. Kirk, Hong-Kun Xu, Asymptotic pointwise contractions, Nonlinear Analysis 69 (2008) 4706–4712] to modular spaces.     

$$\mathcal {H}^+$$-multivalued contractions and their application to homotopy theory

Kikkawa and Suzuki (Nonlinear Anal 69:2942–2949, 2008) and Kikkawa and Suzuki (Fixed Point Theory Appl, 2008, Art. ID 649749) proved some fixed point results that are generalizations of Kannan’s, Nadler’s and Suzuki’s fixed point theorems. Here, we present fixed point results of this kind for multivalued mappings in the setting of \(\mathcal {H}^+\)-metric spaces. The theorems provided allow upgrading of some known results which is shown by examples. Moreover, we give a homotopy result as an application of our main theorem.     

On a new condition for strictly positive definite functions on spheres

Recently, Xu and Cheney (1992) have proved that if all the Legendre coefficients of a zonal function defined on a sphere are positive then the function is strictly positive definite. It will be shown in this paper that, even if finitely many of the Legendre coefficients are zero, the strict positive definiteness can be assured. The results are based on approximation properties of singular integrals, and provide also a completely different proof of the results of Xu and Cheney.

     

Approximating fixed points of Suzuki-generalized nonexpansive mappings

In this paper, we prove weak and strong convergence theorems for Ishikawa iteration of Suzuki-generalized nonexpansive mappings in uniformly convex Banach spaces. Furthermore, we extend the results to CAT(0) spaces. Our work extends the results of Suzuki [T. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mapping, J. Math. Anal. Appl. 340 (2008) 1088–1095] and Takahashi and Kim [W. Takahashi, G.E. Kim, Approximating fixed points of nonexpansive mappings in Banach spaces, Math. Jpn. 48 (1998) 1–9].     

涉及Picard例外值的亚纯函数正规族

本文研究了徐炎等人在文(Xu Y,Wu F Q,Liao L W.Picard values and normal families of meromorphic functions,Proc.R.Soc.Edinburgh,2009,139:1091-1099.)中提出的一个有关亚纯函数正规族猜想,得到了两个正规定则...     

Suzuki?s type characterizations of completeness for partial metric spaces and fixed points for partially ordered metric spaces

Recently, Suzuki [T. Suzuki, A generalized Banach contraction principle that characterizes metric completeness, Proc. Amer. Math. Soc. 136 (2008) 1861-1869] proved a fixed point theorem that is a generalization of the Banach contraction principle and characterizes the metric completeness. In this paper we prove an analogous fixed point result for a self-mapping on a partial metric space or on a partially ordered metric space. Our results on partially ordered metric spaces generalize and extend some recent results of Ran and Reurings [A.C.M. Ran, M.C. Reurings, A fixed point theorem in partially ordered sets and some applications to matrix equations, Proc. Amer. Math. Soc. 132 (2004) 1435-1443], Nieto and Rodríguez-López [J.J. Nieto, R. Rodríguez-López, Contractive mapping theorems in partially ordered sets and applications to ordinary differential equations, Order 22 (2005) 223-239]. We deduce, also, common fixed point results for two self-mappings. Moreover, using our results, we obtain a characterization of partial metric 0-completeness in terms of fixed point theory. This result extends Suzuki?s characterization of metric completeness.