共查询到20条相似文献,搜索用时 46 毫秒
1.
Cristian Conde Mohammad Sal Moslehian Ameur Seddik 《Linear algebra and its applications》2012,436(9):3008-3017
We prove some refinements of an inequality due to X. Zhan in an arbitrary complex Hilbert space by using some results on the Heinz inequality. We present several related inequalities as well as new variants of the Corach–Porta–Recht inequality. We also characterize the class of operators satisfying under certain conditions. 相似文献
2.
Deborah Chun 《Discrete Mathematics》2009,309(8):2592-2595
Let be a matroid with rank function , and let . The deletion–contraction polymatroid with rank function will be denoted . Notice that is uniquely determined by and . Similarly, a deletion–contraction polymatroid determines , unless is a loop or co-loop. This paper will characterize all polymatroids of this deletion–contraction form by giving the set of excluded minors. Vertigan conjectured that the class of -representable deletion–contraction polymatroids is well-quasi-ordered. From this attractive conjecture, both Rota’s Conjecture and the WQO Conjecture for -representable matroids would follow. 相似文献
3.
It is often asserted that the application of mean–variance analysis assumes normal (Gaussian) return distributions or quadratic utility functions. This common mistake confuses sufficient versus necessary conditions for the applicability of modern portfolio theory. If one believes (as does the author) that choice should be guided by the expected utility maxim, then the necessary and sufficient condition for the practical use of mean–variance analysis is that a careful choice from a mean–variance efficient frontier will approximately maximize expected utility for a wide variety of concave (risk-averse) utility functions. This paper reviews a half-century of research on mean–variance approximations to expected utility. The many studies in this field have been generally supportive of mean–variance analysis, subject to certain (initially unanticipated) caveats. 相似文献
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The convergence to equilibrium of renormalized solutions to reaction–cross-diffusion systems in a bounded domain under no-flux boundary conditions is studied. The reactions model complex balanced chemical reaction networks coming from mass-action kinetics and thus do not obey any growth condition, while the diffusion matrix is of cross-diffusion type and hence nondiagonal and neither symmetric nor positive semi-definite, but the system admits a formal gradient-flow or entropy structure. The diffusion term generalizes the population model of Shigesada, Kawasaki and Teramoto to an arbitrary number of species. By showing that any renormalized solution satisfies the conservation of masses and a weak entropy–entropyproduction inequality, it can be proved under the assumption of no boundary equilibria that all renormalized solutions converge exponentially to the complex balanced equilibrium with a rate which is explicit up to a finite dimensional inequality. 相似文献
6.
Salvador Moll Ken Shirakawa 《Calculus of Variations and Partial Differential Equations》2014,51(3-4):621-656
In this paper, a coupled system of two parabolic type initial-boundary value problems is considered. The system is known as the Kobayashi–Warren–Carter model of grain boundary motion in a polycrystal. Kobayashi–Warren–Carter model is derived as a gradient descent flow of an energy functional, which is called “free-energy”, with respect to two unknown variables and it involves a weighted-unknown dependent total variation term. The main goal of this paper is to obtain existence of solutions to this system. We solve the problem by means of a time-discretization of a relaxed system and a highly non-trivial passage to the limit. We point out that our time-discretization method is effective not only for the original Kobayashi–Warren–Carter system but also for its relaxed versions. Therefore, we provide a uniform approach for obtaining solutions to systems associated with this model. 相似文献
7.
Hui Yin Shuyue Chen Jing Jin 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,1(2):969-1001
This paper is concerned with the large time behavior of traveling wave solutions to the Cauchy problem of generalized Benjamin–Bona–Mahony–Burgers
equations
$u_t- u_{txx}- vu_{xx}+\beta u_x+f(u)_x = 0,\, t > 0,\, x \in {\bf R}\quad\quad ({\rm E})$u_t- u_{txx}- vu_{xx}+\beta u_x+f(u)_x = 0,\, t > 0,\, x \in {\bf R}\quad\quad ({\rm E}) 相似文献
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Hui Yin Shuyue Chen Jing Jin 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(6):969-1001
This paper is concerned with the large time behavior of traveling wave solutions to the Cauchy problem of generalized Benjamin–Bona–Mahony–Burgers
equations
10.
Anjan Biswas Ghodrat Ebadi Houria Triki Ahmet Yildirim Nazila Yousefzadeh 《Results in Mathematics》2013,63(1-2):687-703
This paper studies the KdV–Caudrey–Dodd–Gibbon equation. The modified F-expansion method, exp-function method as well as the G′/G method are used to extract a few exact solutions to this equation. Later, the ansatz method is used to obtain the topological 1-soliton solution to this equation. The constraint conditions are also obtained that must remain valid for the existence of these solutions. 相似文献
11.
We study the three-dimensional Cauchy problem of the Poisson–Nernst–Planck–Navier–Stokes equations. We first show that the corresponding stationary system has a unique semi-trivial solution under a general doping profile. Under initial small perturbations around such the semi-trivial stationary solution and small doping profile, we obtain the unique global-in-time solution to the non-stationary system. Moreover, we prove the asymptotic convergence of the solution toward the semi-trivial stationary solution as time tends to infinity. 相似文献
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13.
Mirjam Dür 《Mathematical Programming》2001,91(1):117-125
Branch–and–Bound methods with dual bounding procedures have recently been used to solve several continuous global optimization
problems. We improve results on their convergence theory and give a condition that enables us to detect infeasible partition
sets from the dual optimal value.
Received: May 5, 1999 / Accepted: April 19, 2001?Published online September 17, 2001 相似文献
14.
The convergence of solutions of nonlinear Fokker–Planck–Kolmogorov equations to stationary solutions is studied. Broad sufficient conditions for convergence in variation with an exponential bound are obtained. 相似文献
15.
Takafumi Miyazaki 《The Ramanujan Journal》2018,45(3):601-613
For any given odd prime p and a fixed positive integer D prime to p, we study the equation \(x^2+D^m=p^n\) in positive integers x, m and n. We use a classical work of Dem’janenko in 1965 on a certain quadratic Diophantine equation together with some results concerning the existence of primitive divisors of Lucas sequences to examine our equation when D is a product of \(p-1\) and a square. 相似文献
16.
P. Dutta 《Theoretical and Mathematical Physics》2016,187(3):899-908
We discuss Liouville field theory in the framework of the Schwinger–Dyson approach and derive a functional equation for the three-point structure constant. We prove the existence of a second Schwinger–Dyson equation based on the duality between the screening charge operators and obtain a second functional equation for the structure constant. We use the system of these two equations to uniquely determine the structure constant. 相似文献
17.
To any right comodule coalgebra C over a Hopf algebra H we associate a left H-comodule algebra A. Under certain conditions, in particular in the case where H has nonzero integrals, we show that the category of right C, H-comodules is isomorphic to a certain subcategory of the category of Doi–Hopf modules associated to A. As an application, we investigate the connection between C and the smash coproduct C ? H being right semiperfect. 相似文献
18.
Philippe Laurençot 《偏微分方程通讯》2019,44(9):773-800
Existence of mass-conserving self-similar solutions with a sufficiently small total mass is proved for a specific class of homogeneous coagulation and fragmentation coefficients. The proof combines a dynamical approach to construct such solutions for a regularized coagulation–fragmentation equation in scaling variables and a compactness method. 相似文献
19.
We present a simple direct proof of the classical Sobolev inequality in with best constant from the geometric Brunn–Minkowski–Lusternik inequality.
Research supported in part by NSF Gr. No. 0405587 and B. Zegarlinski’s Pierre de Fermat Grant 2006 from the Région Midi-Pyrénées,
France. 相似文献
20.
Serkan Eryılmaz 《Annals of the Institute of Statistical Mathematics》2011,63(1):101-115
The stress–strength models have been widely used for reliability design of systems. In these models the reliability is defined
as the probability that the strength is larger than the stress. The analysis is then based on the binary reliability theory
since there are two possible states for the system. In this paper, we study the stress–strength reliability in a different
framework assigning more than two states to the system depending on the difference between strength and stress values. In
other words, the stress–strength reliability is studied under multi-state system modeling. System state probabilities are
evaluated and estimated under various assumptions on the system. The multicomponent form is also studied and some results
are provided for large systems. 相似文献
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