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51. CJM 2001 (vol 53 pp. 565)

Hare, Kathryn E.; Sato, Enji
Spaces of Lorentz Multipliers
We study when the spaces of Lorentz multipliers from $L^{p,t} \rightarrow L^{p,s}$ are distinct. Our main interest is the case when $s
Keywords:multipliers, convolution operators, Lorentz spaces, Lorentz-improving multipliers
Categories:43A22, 42A45, 46E30

52. CJM 2000 (vol 52 pp. 381)

Miyachi, Akihiko
Hardy Space Estimate for the Product of Singular Integrals
$H^p$ estimate for the multilinear operators which are finite sums of pointwise products of singular integrals and fractional integrals is given. An application to Sobolev space and some examples are also given.

Keywords:$H^p$ space, multilinear operator, singular integral, fractional integration, Sobolev space

53. CJM 2000 (vol 52 pp. 3)

Aizenberg, Lev; Vidras, Alekos
On Small Complete Sets of Functions
Using Local Residues and the Duality Principle a multidimensional variation of the completeness theorems by T.~Carleman and A.~F.~Leontiev is proven for the space of holomorphic functions defined on a suitable open strip $T_{\alpha}\subset {\bf C}^2$. The completeness theorem is a direct consequence of the Cauchy Residue Theorem in a torus. With suitable modifications the same result holds in ${\bf C}^n$.

Categories:32A10, 42C30

54. CJM 1998 (vol 50 pp. 1236)

Kalton, N. J.; Tzafriri, L.
The behaviour of Legendre and ultraspherical polynomials in $L_p$-spaces
We consider the analogue of the $\Lambda(p)-$problem for subsets of the Legendre polynomials or more general ultraspherical polynomials. We obtain the ``best possible'' result that if $2
Categories:42C10, 33C45, 46B07

55. CJM 1998 (vol 50 pp. 1273)

Lubinsky, D. S.
Mean convergence of Lagrange interpolation for exponential weights on $[-1,1]$
We obtain necessary and sufficient conditions for mean convergence of Lagrange interpolation at zeros of orthogonal polynomials for weights on $[-1,1]$, such as \[ w(x)=\exp \bigl(-(1-x^{2})^{-\alpha }\bigr),\quad \alpha >0 \] or \[ w(x)=\exp \bigl(-\exp _{k}(1-x^{2})^{-\alpha }\bigr),\quad k\geq 1, \ \alpha >0, \] where $\exp_{k}=\exp \Bigl(\exp \bigl(\cdots\exp (\ )\cdots\bigr)\Bigr)$ denotes the $k$-th iterated exponential.

Categories:41A05, 42C99

56. CJM 1998 (vol 50 pp. 605)

Guzmán-Partida, Martha; Pérez-Esteva, Salvador
Hardy spaces of conjugate systems of temperatures
We define Hardy spaces of conjugate systems of temperature functions on ${\bbd R}_{+}^{n+1}$. We show that their boundary distributions are the same as the boundary distributions of the usual Hardy spaces of conjugate systems of harmonic functions.

Categories:42B30, 42A50, 35K05

57. CJM 1998 (vol 50 pp. 29)

Ding, Yong; Lu, Shanzhen
Weighted norm inequalities for fractional integral operators with rough kernel
Given function $\Omega$ on ${\Bbb R^n}$, we define the fractional maximal operator and the fractional integral operator by $$ M_{\Omega,\alpha}\,f(x)=\sup_{r>0}\frac 1{r^{n-\alpha}} \int_{|\,y|1)$, homogeneous of degree zero.

Categories:42B20, 42B25

58. CJM 1997 (vol 49 pp. 1010)

Lorente, Maria
A characterization of two weight norm inequalities for one-sided operators of fractional type
In this paper we give a characterization of the pairs of weights $(\w,v)$ such that $T$ maps $L^p(v)$ into $L^q(\w)$, where $T$ is a general one-sided operator that includes as a particular case the Weyl fractional integral. As an application we solve the following problem: given a weight $v$, when is there a nontrivial weight $\w$ such that $T$ maps $L^p(v)$ into $L^q(\w )$?

Keywords:Weyl fractional integral, weights
Categories:26A33, 42B25

59. CJM 1997 (vol 49 pp. 708)

Duran, Antonio J.; Lopez-Rodriguez, Pedro
Density questions for the truncated matrix moment problem
For a truncated matrix moment problem, we describe in detail the set of positive definite matrices of measures $\mu$ in $V_{2n}$ (this is the set of solutions of the problem of degree $2n$) for which the polynomials up to degree $n$ are dense in the corresponding space ${\cal L}^2(\mu)$. These matrices of measures are exactly the extremal measures of the set $V_n$.

Categories:42C05, 44A60

60. CJM 1997 (vol 49 pp. 175)

Xu, Yuan
Orthogonal Polynomials for a Family of Product Weight Functions on the Spheres
Based on the theory of spherical harmonics for measures invariant under a finite reflection group developed by Dunkl recently, we study orthogonal polynomials with respect to the weight functions $|x_1|^{\alpha_1}\cdots |x_d|^{\alpha_d}$ on the unit sphere $S^{d-1}$ in $\RR^d$. The results include explicit formulae for orthonormal polynomials, reproducing and Poisson kernel, as well as intertwining operator.

Keywords:Orthogonal polynomials in several variables, sphere, h-harmonics
Categories:33C50, 33C45, 42C10
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