共查询到20条相似文献,搜索用时 15 毫秒
1.
Chun-Gil Park Hahng-Yun Chu Won-Gil Park Hee-Jeong Wee 《Czechoslovak Mathematical Journal》2005,55(4):1055-1065
It is shown that every almost linear Pexider mappings f, g, h from a unital C*-algebra
into a unital C*-algebra ℬ are homomorphisms when f(2
n
uy) = f(2
n
u)f(y), g(2
n
uy) = g(2
n
u)g(y) and h(2
n
uy) = h(2
n
u)h(y) hold for all unitaries u ∈
, all y ∈
, and all n ∈ ℤ, and that every almost linear continuous Pexider mappings f, g, h from a unital C*-algebra
of real rank zero into a unital C*-algebra ℬ are homomorphisms when f(2
n
uy) = f(2
n
u)f(y), g(2
n
uy) = g(2
n
u)g(y) and h(2
n
uy) = h(2
n
u)h(y) hold for all u ∈ {v ∈
: v = v* and v is invertible}, all y ∈
and all n ∈ ℤ.
Furthermore, we prove the Cauchy-Rassias stability of *-homomorphisms between unital C*-algebras, and ℂ-linear *-derivations on unital C*-algebras.
This work was supported by Korea Research Foundation Grant KRF-2003-042-C00008.
The second author was supported by the Brain Korea 21 Project in 2005. 相似文献
2.
M. K. Jain R. K. Jain R. K. Mohanty 《Numerical Methods for Partial Differential Equations》1989,5(2):87-95
We present a nine-point fourth-order finite difference method for the nonlinear second-order elliptic differential equation Auxx + Buyy = f(x, y, u, ux, uy) on a rectangular region R subject to Dirichlet boundary conditions u(x, y) = g(x, y) on ?R. We establish, under appropriate conditions O(h4)-convergence of the finite difference scheme. Numerical examples are given to illustrate the method and its fourth-order convergence. 相似文献
3.
Chun-Gil Park 《Bulletin of the Brazilian Mathematical Society》2005,36(1):79-97
It is shown that every almost linear mapping
of a unital Poisson JC*-algebra
to a unital Poisson JC*-algebra
is a Poisson JC*-algebra homomorphism when h(2
n
uy) = h(2
n
u) h(y), h(3
n
u y) = h(3
n
u) h(y) or h(q
n
u y) = h(q
n
u) h(y) for all
, all unitary elements
and n = 0, 1, 2, · · · , and that every almost linear almost multiplicative mapping
is a Poisson JC*-algebra homomorphism when h(2x) = 2h(x), h(3x) = 3h(x) or h(qx) = qh(x) for all
. Here the numbers 2, 3, q depend on the functional equations given in the almost linear mappings or in the almost linear almost multiplicative mappings.Moreover, we prove the Cauchy–Rassias stability of Poisson JC*-algebra homomorphisms in Poisson JC*-algebras.*This work was supported by grant No. R05-2003-000-10006-0 from the Basic Research Program of the Korea Science & Engineering Foundation. 相似文献
4.
Chun Gil PARK Jin Chuan HOU Sei Qwon OH 《数学学报(英文版)》2005,21(6):1391-1398
It is shown that every almost *-homomorphism h : A→B of a unital JC*-algebra A to a unital JC*-algebra B is a *-homomorphism when h(rx) = rh(x) (r 〉 1) for all x∈A, and that every almost linear mapping h : A→B is a *-homomorphism when h(2^nu o y) - h(2^nu) o h(y), h(3^nu o y) - h(3^nu) o h(y) or h(q^nu o y) = h(q^nu) o h(y) for all unitaries u ∈A, all y ∈A, and n = 0, 1,.... Here the numbers 2, 3, q depend on the functional equations given in the almost linear mappings. We prove that every almost *-homomorphism h : A→B of a unital Lie C*-algebra A to a unital Lie C*-algebra B is a *-homomorphism when h(rx) = rh(x) (r 〉 1) for all x ∈A. 相似文献
5.
6.
V. L. Pryadiev 《Journal of Mathematical Sciences》2007,147(1):6470-6482
7.
Václav Tryhuk 《Czechoslovak Mathematical Journal》2000,50(3):499-508
The paper describes the general form of an ordinary differential equation of the second order which allows a nontrivial global transformation consisting of the change of the independent variable and of a nonvanishing factor. A result given by J. Aczél is generalized. A functional equation of the form
f( t,uy,wy + uuz ) = f( x,y,z )u2 u+ g( t,x,u,u,w )uz + h( t,x,u,u,w )y + 2uwzf\left( {t,\upsilon y,wy + u\upsilon z} \right) = f\left( {x,y,z} \right)u^2 \upsilon + g\left( {t,x,u,\upsilon ,w} \right)\upsilon z + h\left( {t,x,u,\upsilon ,w} \right)y + 2uwz 相似文献
8.
It is established that the linear problemu
u
–a
2
u
xx
=g(x,t),u(0,t) =u(x, t + T) =u(x,t) is always solvable in the function spaceA = {g:g(x,t) =g(x,t+T) =g( –x,t) = –g(–x,t)} provided thataTq = (2p – 1) and (2p – 1,q) = 1, wherepandq are integer numbers. To prove this statement, an exact solution is constructed in the form of an integral operator, which is used to prove the existence of a solution of a periodic boundary-value problem for a nonlinear second-order wave equation. The results obtained can be used when studying the solutions to nonlinear boundary-value problems by asymptotic methods.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 8, pp. 1115–1121, August, 1993. 相似文献
9.
W. Stadler 《Journal of Optimization Theory and Applications》1976,18(1):119-140
Preference optimality is an optimality concept in multicriteria problems, that is, in problems where several criteria are to beoptimized simultaneously. Formally, one wishes to optimizeN criteriag
i(·) or, equivalently, a criterion vectorg(·)
N
, subject to either functional constraints in programming or to side conditions which are differential equations in optimal control. Subject to these constraints, one obtains forg(·) a set of attainable values in
N
. This set is preordered by the introduction of a complete preordering ; a controlu*(·) or a decisionx*, then, is preference-optimal if it results ing(u*(·))g(u(·)) for all admissible controlsu(·) or ifg(x*)g(x) for all feasible decisionsx. The present paper concerns sufficient conditions for preference-optimal control and for preference-optimal decisions. 相似文献
10.
A. P. Kiselev 《Journal of Mathematical Sciences》2003,117(2):3945-3946
New solutions of the wave equation with three space variables of the form u = g(x,y,z,t)f(), where the functions g and = (x,y,z,t) are some specified functions and f is an arbitrary function of one variable, are presented. Bibliography: 4 titles. 相似文献
11.
D. A. Edwards 《Archiv der Mathematik》2005,84(6):559-567
Suppose that X is a topological space with preorder , and that –g, f are bounded upper semicontinuous functions on X such that g(x) f(y) whenever x y. We consider the question whether there exists a bounded increasing continuous function h on X such that g h f, and obtain an existence theorem that gives necessary and sufficient conditions. This result leads to an extension theorem giving conditions that allow a bounded increasing continuous function defined on an open subset of X to be extended to a function of the same type on X. The application of these results to extremally disconnected locally compact spaces is studied.Received: 26 May 2004 相似文献
12.
A spectral collocation method with collocation at the Legendre Gauss points is discussed for solving the Helmholtz equation –u+(x,y)u=f(x,y) on a rectangle with the solution u subject to inhomogeneous Robin boundary conditions. The convergence analysis of the method is given in the case of u satisfying Dirichlet boundary conditions. A matrix decomposition algorithm is developed for the solution of the collocation problem in the case the coefficient (x,y) is a constant. This algorithm is then used in conjunction with the preconditioned conjugate gradient method for the solution of the spectral collocation problem with the variable coefficient (x,y). 相似文献
13.
Chun-Gil Park 《Bulletin of the Brazilian Mathematical Society》2005,36(3):333-362
Let X and Y be vector spaces. It is shown that a mapping f : X → Y satisfies the functional equation
14.
We consider the problem of finding, from the final data u(x,y,T)=g(x,y), the initial data u(x,y,0) of the temperature function u(x,y,t),(x,y)I=(0,π)×(0,π),t[0,T] satisfying the following system
15.
The linear equation Δ2u = 1 for the infinitesimal buckling under uniform unit load of a thin elastic plate over ?2 has the particularly interesting nonlinear generalization Δg2u = 1, where Δg = e?2u Δ is the Laplace‐Beltrami operator for the metric g = e2ug0, with g0 the standard Euclidean metric on ?2. This conformal elliptic PDE of fourth order is equivalent to the nonlinear system of elliptic PDEs of second order Δu(x)+Kg(x) exp(2u(x)) = 0 and Δ Kg(x) + exp(2u(x)) = 0, with x ∈ ?2, describing a conformally flat surface with a Gauss curvature function Kg that is generated self‐consistently through the metric's conformal factor. We study this conformal plate buckling equation under the hypotheses of finite integral curvature ∫ Kg exp(2u)dx = κ, finite area ∫ exp(2u)dx = α, and the mild compactness condition K+ ∈ L1(B1(y)), uniformly w.r.t. y ∈ ?2. We show that asymptotically for |x|→∞ all solutions behave like u(x) = ?(κ/2π)ln |x| + C + o(1) and K(x) = ?(α/2π) ln|x| + C + o(1), with κ ∈ (2π, 4π) and . We also show that for each κ ∈ (2π, 4π) there exists a K* and a radially symmetric solution pair u, K, satisfying K(u) = κ and maxK = K*, which is unique modulo translation of the origin, and scaling of x coupled with a translation of u. © 2001 John Wiley & Sons, Inc. 相似文献
16.
G. M. Ewing 《Journal of Optimization Theory and Applications》1980,32(3):307-325
For a selected family of Lagrange-type control problems involving a nonnegative integral costJ
T
(y,u) over the interval [0,T], 0<T<, with system conditions consisting of differential inequalities and/or equalities, the following material is treated: (i) a resumé of relevant necessary conditions and sufficient conditions for a pair (y
T
,u
T
) to minimizeJ
T
(y,u); (ii) conditions sufficient for the convergence asT of minimizing pairs (y
T
,u
T
) over [0,T] to a limit pair (y
,u
) over the infinite-time interval [0, ); (iii) conditions sufficient for (y
,u
) to minimize the costJ
(y,u) over [0, ); and (iv) conditions sufficient for the optimal cost per unit timeJ
T
(y
T
,u
T
)/T to have a limit asT. 相似文献
17.
Vicenţiu Rădulescu 《Archiv der Mathematik》2005,84(6):538-550
We consider the nonlinear Sturm-Liouville problem –u = f(u) + h in (0, 1), u(0) = u(1) = 0, where h L2(0,1) and f is a positive convex nonlinearity with superlinear growth at infinity. Our main result establishes that the above boundary value problem admits a finite number of solutions but it cannot have infinitely many solutions.Received: 8 July 2004 相似文献
18.
19.
The nonlinear hyperbolic equation ∂2u(x, y)/∂x ∂y + g(x, y)f(u(x, y)) = 0 with u(x, 0) = φ(x) and u(0, y) = Ψ(y), considered by [1.], 31–45) under appropriate smoothness conditions, is solvable by the author's decomposition method (“Stochastic Systems,” Academic Press, 1983 and “Nonlinear Stochastic Operator Equations,” Academic Press, 1986). 相似文献
20.
The functional equationf(x,y)+g(x)h(y)F(u/1?x,ν/1?y)=f(u,ν)+g(u)h(ν)F(x/1?u,y/1?ν) ... (1) forx, y, u, ν ∈ [0, 1) andx+u,y+ν ∈ [0,1) whereg andh satisfy the functional equationφ (x+y?xy)=φ(x)φ(y)... (2) has been solved for some non-constant solution of (2) in [0, 1] withφ (0)=1,φ(1)=0 and the solution is used in characterising some measures of information. 相似文献
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