共查询到20条相似文献,搜索用时 494 毫秒
1.
On the iterates of Euler's function 总被引:1,自引:0,他引:1
R. Warlimont 《Archiv der Mathematik》2001,76(5):345-349
Asymptotic representations are given for the three sums ?n £ x j(n)/j(j(n))\textstyle\sum\limits \limits _{n\le x} \varphi (n)/\varphi \bigl (\varphi (n)\bigr ), ?n £ x j(n)/j(j(n))\textstyle\sum\limits \limits _{n\le x} \varphi (n)/\varphi \bigl (\varphi (n)\bigr ), ?n £ x log j(n)/j(j(n)) ; j\textstyle\sum\limits \limits _{n\le x}\ \log \, \varphi (n)/\varphi \bigl (\varphi (n)\bigr )\ ; \ \varphi is Euler's function. 相似文献
2.
Let X be a realcompact space and H:C(X)?\mathbbR{H:C(X)\rightarrow\mathbb{R}} be an identity and order preserving group homomorphism. It is shown that H is an evaluation at some point of X if and only if there is j ? C(\mathbbR){\varphi\in C(\mathbb{R})} with ${\varphi(r)>\varphi(0)}${\varphi(r)>\varphi(0)} for all r ? \mathbbR-{0}{r\in\mathbb{R}-\{0\}} for which H°j = j°H{H\circ\varphi=\varphi\circ H} . This extends (and unifies) classical results by Hewitt and Shirota. 相似文献
3.
Consider j = f +[`(g)]\varphi = f + \overline {g}, where f and g are polynomials, and let TjT_{\varphi} be the Toeplitz operators with the symbol j\varphi. It is known that if TjT_{\varphi} is hyponormal then |f¢(z)|2 3 |g¢(z)|2|f'(z)|^{2} \geq |g'(z)|^{2} on the unit circle in the complex plane. In this paper, we show that it is also a necessary and sufficient condition under
certain assumptions. Furthermore, we present some necessary conditions for the hyponormality of TjT_{\varphi} on the weighted Bergman space, which generalize the results of I. S. Hwang and J. Lee. 相似文献
4.
Constantin Costara 《Integral Equations and Operator Theory》2012,73(1):7-16
Let X be a complex Banach space and let B(X){\mathcal{B}(X)} be the space of all bounded linear operators on X. For x ? X{x \in X} and T ? B(X){T \in \mathcal{B}(X)}, let rT(x) = limsupn ? ¥ || Tnx|| 1/n{r_{T}(x) =\limsup_{n \rightarrow \infty} \| T^{n}x\| ^{1/n}} denote the local spectral radius of T at x. We prove that if j: B(X) ? B(X){\varphi : \mathcal{B}(X) \rightarrow \mathcal{B}(X)} is linear and surjective such that for every x ? X{x \in X} we have r
T
(x) = 0 if and only if rj(T)(x) = 0{r_{\varphi(T)}(x) = 0}, there exists then a nonzero complex number c such that j(T) = cT{\varphi(T) = cT} for all T ? B(X){T \in \mathcal{B}(X) }. We also prove that if Y is a complex Banach space and j:B(X) ? B(Y){\varphi :\mathcal{B}(X) \rightarrow \mathcal{B}(Y)} is linear and invertible for which there exists B ? B(Y, X){B \in \mathcal{B}(Y, X)} such that for y ? Y{y \in Y} we have r
T
(By) = 0 if and only if rj( T) (y)=0{ r_{\varphi ( T) }(y)=0}, then B is invertible and there exists a nonzero complex number c such that j(T) = cB-1TB{\varphi(T) =cB^{-1}TB} for all T ? B(X){T \in \mathcal{B}(X)}. 相似文献
5.
Let θ(ζ) be a Schur operator function, i.e., it is defined and holomorphic on the unit disk
:= C : 1 {\mathbb {D} := \{\zeta \in \mathbb {C} : \vert\zeta\vert < 1 \}} and its values are contractive operators acting from one Hilbert space into another one. In the first part of the paper the
outer and *-outer Schur operator functions j(z){\varphi(\zeta)} and ψ(ζ) which describe respectively the deviations of the function θ(ζ) from inner and *-inner operator functions are studied. If j(z) 1 0{\varphi(\zeta)\neq 0} , then it means that in the scattering system for which θ(ζ) is the transfer function a portion of “information” comes inward the system and does not go outward, i.e., it is left
in the internal channels of the system (Sect. 6). The function ψ(ζ) has the analogous property for the dual system. For this reason these functions are called the defect functions of the function θ(ζ). The explicit form of the defect functions j(z){\varphi(\zeta)} and ψ(ζ) is obtained and the analytic connection of these functions with the function θ(ζ) is described (Sects. 3, 5). The operator functions
(l j(z)q(z)){\left(\begin{array}{l} \varphi(\zeta)\\ \theta(\zeta)\end{array}\right)} and (ψ(ζ), θ(ζ)) are Schur functions as well (Sect. 3). It is important that there exists the unique contractive measurable operator function
χ(t),
t ? ?\mathbb D{t\in\partial\mathbb {D}} , such that the operator function
(l c(t) j(t)y(t) q(t) ){\left(\begin{array}{l} \chi(t)\quad \varphi(t)\\ \psi(t)\quad \theta(t) \end{array}\right)} ,
t ? ?\mathbb D,{t\in\partial\mathbb {D},} is also contractive (Part II, Sect. 12). The second part of the paper is devoted to studying the properties of the function
χ(t). Specifically, it is shown that the function χ(t) is the scattering suboperator through the internal channels of the scattering system for which θ(ζ) is the transfer function (Part II, Sect. 12). 相似文献
6.
Carme Cascante Joan Fàbrega Daniel Pascuas 《Integral Equations and Operator Theory》2011,69(3):373-391
For weighted Toeplitz operators TNj{{\mathcal T}^N_\varphi} defined on spaces of holomorphic functions in the unit ball, we derive regularity properties of the solutions f to the equation TNj(f)=h{{\mathcal T}^N_\varphi(f)=h} in terms of the regularity of the symbol φ and the data h. As an application, we deduce that if
f\not o 0{f\not\equiv0} is a function in the Hardy space H
1 such that its argument [`(f)]/f{\bar f/f} is in a Lipschitz space on the unit sphere
\mathbb S{{\mathbb S}}, then f is also in the same Lipschitz space, extending a result of Dyakonov to several complex variables. 相似文献
7.
R. Ger 《Aequationes Mathematicae》2000,60(3):268-282
Summary. Quite recently C. Alsina, P. Cruells and M. S. Tomás [2], motivated by F. Suzuki's property of isosceles trapezoids, have proposed the following orthogonality relation in a real normed linear space (X, ||·||) (X, \Vert \cdot \Vert) : two vectors x,y ? X x,y \in X are T-orthogonal whenever¶||z-x ||2 + ||z-y ||2 = ||z ||2 + ||z-(x+y) ||2 \Vert z-x \Vert^2 + \Vert z-y \Vert^2 = \Vert z \Vert^2 + \Vert z-(x+y) \Vert^2 ¶for every z ? X z \in X . A natural question arises whether an analogue of T-orthogonality may be defined in any real linear space (without a norm structure). Our proposal reads as follows. Given a functional j \varphi on a real linear space X we say that two vectors x,y ? X x,y \in X are j \varphi -orthogonal (and write x^jy x\perp_{\varphi}y ) provided that Dx,yj = 0 \Delta_{x,y}\varphi = 0 (Dh1,h2 \Delta_{h_1,h_2} stands here and in the sequel for the superposition Dh1 °Dh2 \Delta_{h_1} \circ \Delta_{h_2} of the usual difference operators).¶We are looking for necessary and/or sufficient conditions upon the functional j \varphi to generate a j \varphi -orthogonality such that the pair X,^j X,\perp_{\varphi} forms an orthogonality space in the sense of J. Rätz (cf. [6]). Two new characterizations of inner product spaces as well as a generalization of some results obtained in [2] are presented. 相似文献
8.
Let M{\mathcal M} be a σ-finite von Neumann algebra and
\mathfrak A{\mathfrak A} a maximal subdiagonal algebra of M{\mathcal M} with respect to a faithful normal conditional expectation F{\Phi} . Based on Haagerup’s noncommutative L
p
space Lp(M){L^p(\mathcal M)} associated with M{\mathcal M} , we give a noncommutative version of H
p
space relative to
\mathfrak A{\mathfrak A} . If h
0 is the image of a faithful normal state j{\varphi} in L1(M){L^1(\mathcal M)} such that j°F = j{\varphi\circ \Phi=\varphi} , then it is shown that the closure of
{\mathfrak Ah0\frac1p}{\{\mathfrak Ah_0^{\frac1p}\}} in Lp(M){L^p(\mathcal M)} for 1 ≤ p < ∞ is independent of the choice of the state preserving F{\Phi} . Moreover, several characterizations for a subalgebra of the von Neumann algebra M{\mathcal M} to be a maximal subdiagonal algebra are given. 相似文献
9.
Examples of factorial threefolds complete intersection in $${\mathbb{P}^5}$$ with many singularities
Pietro Sabatino 《Ricerche di matematica》2009,58(2):285-297
Denote by ν
m
(d) the maximal integer for which there exists for d >> 0{d \gg 0} a threefold
X ì \mathbbP5{X\subset \mathbb{P}^5} complete intersection of hypersurfaces of degree respectively d and d − 1 such that X has only ordinary singularities of order m and |Sing(X)| = ν
m
(d). We prove that, nm(d) 3 j(d){\nu_m(d)\ge \varphi(d)} where j(d) ~ d5{\varphi(d)\sim d^5} asymptotically. This result extends (Di Gennaro and Franco in Commun Contemp Math 10(5):745–764, 2008, Corollary 2.10). 相似文献
10.
We establish conditions for the existence of an invariant set of the system of differential equations
\fracdj dt = a( j ), \fracdxdt = P( j )x + F( j, x ), \frac{{d{\rm{\varphi}} }}{{dt}} = a\left( {\rm{\varphi}} \right),\quad \frac{{dx}}{{dt}} = P\left( {\rm{\varphi}} \right)x + F\left( {{\rm{\varphi}}, x} \right), 相似文献
11.
Let j{\varphi} be an analytic self-map of the unit disk
\mathbbD{\mathbb{D}},
H(\mathbbD){H(\mathbb{D})} the space of analytic functions on
\mathbbD{\mathbb{D}} and
g ? H(\mathbbD){g \in H(\mathbb{D})}. The boundedness and compactness of the operator DCj : H¥ ? Z{DC_\varphi : H^\infty \rightarrow { \mathcal Z}} are investigated in this paper. 相似文献
12.
Let
W ì \BbbR2\Omega \subset \Bbb{R}^2 denote a bounded domain whose boundary
?W\partial \Omega is Lipschitz and contains a segment G0\Gamma_0 representing
the austenite-twinned martensite interface. We prove
infu ? W(W) òW j(?u(x,y))dxdy=0\displaystyle{\inf_{{u\in \cal W}(\Omega)} \int_\Omega \varphi(\nabla
u(x,y))dxdy=0} 相似文献
13.
Alejandro Rodríguez-Martínez 《Integral Equations and Operator Theory》2012,72(3):301-308
We prove a criterion that guarantees that in a given class of operators the set of hypercyclic ones is residual. We also prove
the existence of quasinilpotent Volterra composition operators, Vj{V_\varphi} , such that both Vj{V_\varphi} and Vj*{V_\varphi^\star} are supercyclic and both I + Vj{I + V_\varphi} and I + Vj*{I + V_\varphi^\star} are hypercyclic. 相似文献
14.
Let H be the symmetric second-order differential operator on L 2(R) with domain ${C_c^\infty({\bf R})}
15.
Goro Akagi 《Journal of Evolution Equations》2011,11(1):1-41
Let V and V* be a real reflexive Banach space and its dual space, respectively. This paper is devoted to the abstract Cauchy problem
for doubly nonlinear evolution equations governed by subdifferential operators with non-monotone perturbations of the form:
?V yt (u¢(t)) + ?V j(u(t)) + B(t, u(t)) ' f(t){\partial_V \psi^t (u{^\prime}(t)) + \partial_V \varphi(u(t)) + B(t, u(t)) \ni f(t)} in V*, 0 < t < T, u(0) = u
0, where ?V yt, ?V j: V ? 2V*{\partial_V \psi^t, \partial_V \varphi : V \to 2^{V^*}} denote the subdifferential operators of proper, lower semicontinuous and convex functions yt, j: V ? (-¥, +¥]{\psi^t, \varphi : V \to (-\infty, +\infty]}, respectively, for each t ? [0,T]{t \in [0,T]}, and f : (0, T) → V* and u0 ? V{u_0 \in V} are given data. Moreover, let B be a (possibly) multi-valued operator from (0, T) × V into V*. We present sufficient conditions for the local (in time) existence of strong solutions to the Cauchy problem as well as
for the global existence. Our framework can cover evolution equations whose solutions might blow up in finite time and whose
unperturbed equations (i.e., B o 0{B \equiv 0}) might not be uniquely solved in a doubly nonlinear setting. Our proof relies on a couple of approximations for the equation
and a fixed point argument with a multi-valued mapping. Moreover, the preceding abstract theory is applied to doubly nonlinear
parabolic equations. 相似文献
16.
M. C. Zdun 《Aequationes Mathematicae》2001,61(3):239-254
Summary. We investigate the bounded solutions j:[0,1]? X \varphi:[0,1]\to X of the system of functional equations¶¶j(fk(x))=Fk(j(x)), k=0,?,n-1,x ? [0,1] \varphi(f_k(x))=F_k(\varphi(x)),\;\;k=0,\ldots,n-1,x\in[0,1] ,(*)¶where X is a complete metric space, f0,?,fn-1:[0,1]?[0,1] f_0,\ldots,f_{n-1}:[0,1]\to[0,1] and F0,...,Fn-1:X? X F_0,...,F_{n-1}:X\to X are continuous functions fulfilling the boundary conditions f0(0) = 0, fn-1(1) = 1, fk+1(0) = fk(1), F0(a) = a,Fn-1(b) = b,Fk+1(a) = Fk(b), k = 0,?,n-2 f_{0}(0) = 0, f_{n-1}(1) = 1, f_{k+1}(0) = f_{k}(1), F_{0}(a) = a,F_{n-1}(b) = b,F_{k+1}(a) = F_{k}(b),\,k = 0,\ldots,n-2 , for some a,b ? X a,b\in X . We give assumptions on the functions fk and Fk which imply the existence, uniqueness and continuity of bounded solutions of the system (*). In the case X = \Bbb C X= \Bbb C we consider some particular systems (*) of which the solutions determine some peculiar curves generating some fractals. If X is a closed interval we give a collection of conditions which imply respectively the existence of homeomorphic solutions, singular solutions and a.e. nondifferentiable solutions of (*). 相似文献
17.
Vincent Thilliez 《Monatshefte für Mathematik》2010,13(2):443-453
In the first part of this work, we consider a polynomial j(x,y)=yd+a1(x)yd-1+?+ad(x){\varphi(x,y)=y^d+a_1(x)y^{d-1}+\cdots+a_d(x) } whose coefficients a
j
belong to a Denjoy-Carleman quasianalytic local ring E1(M){\mathcal{E}_1(M) }. Assuming that E1(M){\mathcal{E}_1(M) } is stable under derivation, we show that if h is a germ of C
∞ function such that j(x,h(x))=0{ \varphi(x,h(x))=0 }, then h belongs to E1(M){\mathcal{E}_1(M) }. This extends a well-known fact about real-analytic functions. We also show that the result fails in general for non-quasianalytic
ultradifferentiable local rings. In the second part of the paper, we study a similar problem in the framework of ultraholomorphic
functions on sectors of the Riemann surface of the logarithm. We obtain a result that includes suitable non-quasianalytic
situations. 相似文献
18.
In [6] the authors introduced the notion of quasi-polynomial function as being a mapping f : X n → X defined and valued on a bounded chain X and which can be factorized as ${f(x_1,\ldots,x_n)=p(\varphi(x_1),\ldots,\varphi(x_n))}
19.
Let G be a finite domain in the complex plane with K-quasicon formal boundary, z
0
be an arbitrary fixed point in G and p>0. Let jp ( z ): = òx0 x [ f( z) ]2/8 dz\varphi _p \left( z \right): = \int_{x_0 }^x {\left[ {\phi \left( \zeta \right)} \right]^{2/8} } d\zeta , and let \iintc | jp ( z ) - Px1 (z) |p d0x \iint\limits_c {\left| {\varphi _p \left( z \right) - P_x^1 (z)} \right|^p d0_x } in the class \mathop ?n \mathop \prod \limits_n of all polynomials of degree [`(G)]\bar G in case of $p > 2 - \frac{{K^2 + 1}}{{2K^4 }}$p > 2 - \frac{{K^2 + 1}}{{2K^4 }}
. 相似文献
20.
The aim of this study is to prove global existence of classical solutions for systems of the form ${\frac{\partial u}{\partial t} -a \Delta u=-f(u,v)}
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