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In 1985, W.K.Hayman (Bayer. Akad. Wiss. Math.-Natur. Kl. Sitzungsber, 1984(1985), 1-13.) proved that there do not exist non-constant meromorphic functions $f,$ $g$ and $h$ satisfying the functional equation $f^n+g^n+h^n=1$ for $n\geq 9.$ We prove that there do not exist non-constant meromorphic solutions $f,$ $g,$ $h$ satisfying the functional equation $f^8+g^8+h^8=1.$ In 1971, N. Toda (T\^{o}hoku Math. J. 23(1971), no. 2, 289-299.) proved that there do not exist non-constant entire functions $f,$ $g,$ $h$ satisfying $f^n+g^n+h^n=1$ for $n\geq 7.$ We prove that there do not exist non-constant entire functions $f,$ $g,$ $h$ satisfying the functional equation $f^6+g^6+h^6=1.$ Our results answer questions of G. G. Gundersen., Comment: 40 pages. arXiv admin note: text overlap with arXiv:math/9310226 by other authors

In 1992, Gundersen (Complex Var. Elliptic Equ.20 (1992), no. 1-4, 99-106.) proposed the following famous open question: if two non-constant meromorphic functions share three values IM and share a fourth value CM, then do the functions necessarily share all four values CM? The open question is a long-standing question in the studies of the Nevanlinna$'$s value distribution theory of meromorphic functions, and has not been completely resolved by now. In this paper, we prove that if two distinct non-constant meromorphic functions $f$ and $g$ of finite order share $0,$ $1,$ $c$ IM and $\infty$ CM, where $c$ is a finite complex value such that $c\not\in\{0,1\},$ then $f$ and $g$ share $0,$ $1,$ $c,$ $\infty$ CM. Applying the main result obtained in this paper, we completely resolve a question proposed by Gary G. Gundersen on Page 458 of his paper (J. London Math. Soc. 20(1979), no. 2, 457-466.)concerning the nonexistence of two distinct non-constant meromorphic functions sharing three distinct values DM and a fourth value CM. The obtained result also improves the corresponding result on Pages 109-117 in (E. Mues, Bemerkungen zum vier-punkte-satz, Complex Methods on Partial Diferential Equations, 109-117, Math. Res. 53, Akademie-Verlag, Berlin, 1989.) concerning the nonexistence of two distinct non-constant entire functions that share three distinct finite values DM. Examples are provided to show that the main results obtained in this paper, in a sense, are best possible., Comment: The total pages of the present paper is 39. Neither figures nor conferences are related to this present paper

We investigate the propagation of the gravitational waves in a cosmological background. Based on the framework of spatially covariant gravity, we derive the general quadratic action for the gravitational waves. The spatial derivatives of the extrinsic curvature and the parity-violating terms are systematically introduced. Special attention is paid to the propagation speed of the gravitational waves. We find that it is possible to make the two polarization modes propagate in the same speed, which may differ from that of the light, in the presence of parity-violating terms in the action. In particular, we identify a large class of spatially covariant gravity theories with parity violation, in which both the polarization modes propagate in the speed of light. Our results imply that there are more possibilities in the framework of spatially covariant gravity in light of the propagation speed of the gravitational waves., Comment: 20 pages

The purpose of this article is to study the uniqueness problem for meromorphic mappings from $\mathbb{C}^{n}$ into the complex projective space $\mathbb{P}^{N}(\mathbb{C}).$ By making using of the method of dealing with multiple values due to L. Yang and the technique of Dethloff-Quang-Tan respectively, we obtain two general uniqueness theorems which improve and extend some known results of meromorphic mappings sharing hyperplanes in general position., Comment: 10 pages

In this paper, we shall study the uniqueness problems on meromorphic functions sharing a polynomial. We give a complete answer to a problem posed by Fang Mingliang. Our results improve or generalize those given by Fang and Hua, Yang and Hua, Fang, Fang and Qiu, Lin and Yi, Zhang, Xu, et al., Comment: The authors regret Lemmma 2.8 is not cited correctly, which is different with [17. Theorem 4.8]