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UNIFORM QUASI-DIFFERENTIABILITY OF SEMIGROUP TO NONLINEAR REACTION-DIFFUSION EQUATIONS WITH SUPERCRITI C AL EXPONENT 被引量:1
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作者 钟延生 孙春友 《Acta Mathematica Scientia》 SCIE CSCD 2017年第2期301-315,共15页
A new approach, is established to show that the semigroup {S(t)≥0 generated by a reaction-diffusion equation with supercritical exponent is uniformly quasi-differentiable in L^q(Ω) (2 ≤ q 〈 ∞) with respect ... A new approach, is established to show that the semigroup {S(t)≥0 generated by a reaction-diffusion equation with supercritical exponent is uniformly quasi-differentiable in L^q(Ω) (2 ≤ q 〈 ∞) with respect to the initial value. As an application, this proves the upper-bound of fractal dimension for its global attractor in the corresponding space. 展开更多
关键词 Uniform quasi-differentiability semigroup reaction-diffusion equation
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Calculus of Generalized Quasi-differentiable Functions I: Some Results on the Space of Pairs of Convex-Set Collections 被引量:3
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作者 张宏伟 张立卫 夏尊铨 《Northeastern Mathematical Journal》 CSCD 2003年第1期75-85,共11页
A Riesz space K1 whose elements are pairs of convex-set collections is presented for the study on the calculus of generalized quasi-differentiable functions. The space K1 is constructed by introducing a well-defined e... A Riesz space K1 whose elements are pairs of convex-set collections is presented for the study on the calculus of generalized quasi-differentiable functions. The space K1 is constructed by introducing a well-defined equivalence relation among pairs of collections of convex sets. Some important properties on the norm and operations in K1 are given. 展开更多
关键词 convex-set collection Riesz space quasi-differentiable function quasi-differential
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On the Spectra of General Ordinary Quasi-Differential Operators and Their L2w-Solutions
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2022年第3期186-205,共20页
In this paper, we consider the general ordinary quasi-differential expression τ of order n with complex coefficients and its formal adjoint τ<sup>+</sup> on the interval [a,b). We shall show in the case ... In this paper, we consider the general ordinary quasi-differential expression τ of order n with complex coefficients and its formal adjoint τ<sup>+</sup> on the interval [a,b). We shall show in the case of one singular end-point and under suitable conditions that all solutions of a general ordinary quasi-differential equation are in the weighted Hilbert space provided that all solutions of the equations and its adjoint are in . Also, a number of results concerning the location of the point spectra and regularity fields of the operators generated by such expressions may be obtained. Some of these results are extensions or generalizations of those in the symmetric case, while the others are new. 展开更多
关键词 General Ordinary quasi-differential Expressions Regular and Singular End-Points Singular Differential Operators Essential Spectra Point Spectra and Regularity Fields
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The Products of Regularly Solvable Operators with Their Spectra in Direct Sum Spaces
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2013年第4期415-429,共15页
In this paper, we consider the general quasi-differential expressions each of order n with complex coefficients and their formal adjoints on the interval (a,b). It is shown in direct sum spaces of functions defined on... In this paper, we consider the general quasi-differential expressions each of order n with complex coefficients and their formal adjoints on the interval (a,b). It is shown in direct sum spaces of functions defined on each of the separate intervals with the cases of one and two singular end-points and when all solutions of the equation and its adjoint are in (the limit circle case) that all well-posed extensions of the minimal operator have resolvents which are HilbertSchmidt integral operators and consequently have a wholly discrete spectrum. This implies that all the regularly solvable operators have all the standard essential spectra to be empty. These results extend those of formally symmetric expression studied in [1-10] and those of general quasi-differential expressions in [11-19]. 展开更多
关键词 Product of quasi-differential EXPRESSIONS Regular and Singular ENDPOINTS Regularly SOLVABLE OPERATORS Essential Spectra Hilbert-Schmidt Integral OPERATORS
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On the Domains of General Ordinary Differential Operators in the Direct Sum Spaces
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2022年第3期206-228,共23页
Given general quasi-differential expressions , each of order n with complex coefficients and their formal adjoint are on the interval [a,b) respectively, we give a characterization of all regularly solvable operators ... Given general quasi-differential expressions , each of order n with complex coefficients and their formal adjoint are on the interval [a,b) respectively, we give a characterization of all regularly solvable operators and their adjoints generated by a general ordinary quasi-differential expression in the direct sum Hilbert spaces . The domains of these operators are described in terms of boundary conditions involving -solutions of the equations and their adjoint on the intervals [a<sub>p</sub>,b<sub>p</sub>). This characterization is an extension of those obtained in the case of one interval with one and two singular end-points of the interval (a,b), and is a generalization of those proved in the case of self-adjoint and J-self-adjoint differential operators as a special case, where J denotes complex conjugation. 展开更多
关键词 quasi-differential Expressions Regular and Singular Equations Minimal and Maximal Operators Regularly Solvable Operators J-Self-Adjoint Extension Boundary Conditions
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The Well-Posed Operators with Their Spectra in Lpw-Spaces
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2023年第6期347-368,共22页
In this paper, we have considered the general ordinary quasi-differential operators generated by a general quasi-differential expression τ<sub>p,q</sub> in L<sup>p</sup>w</sub>-spaces of... In this paper, we have considered the general ordinary quasi-differential operators generated by a general quasi-differential expression τ<sub>p,q</sub> in L<sup>p</sup>w</sub>-spaces of order n with complex coefficients and its formal adjoint τ<sup>+</sup><sub>q',p' </sub>in L<sup>p</sup>w</sub>-spaces for arbitrary p,q∈[1,∞). We have proved in the case of one singular end-point that all well-posed extensions of the minimal operator T<sub>0</sub> (τ<sub>p,q</sub>) generated by such expression τ<sub>p,q</sub> and their formal adjoint on the interval [a,b) with maximal deficiency indices have resolvents which are Hilbert-Schmidt integral operators and consequently have a wholly discrete spectrum. This implies that all the regularly solvable operators have all the standard essential spectra to be empty. Also, a number of results concerning the location of the point spectra and regularity fields of the operators generated by such expressions can be obtained. Some of these results are extensions or generalizations of those in the symmetric case, while others are new. 展开更多
关键词 quasi-differential Expressions Regular and Singular Endpoints Minimal and Maximal Operators Regularly Solvable Operators Well-Posed Operators Deficiency Indices
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