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  • P-ISSN3059-0604
  • E-ISSN3059-1309
  • KCI

HILBERT-SCHMIDT INTERPOLATION ON AX=Y IN A TRIDIAGONAL ALGEBRA ALG<TEX>${\pounds}$</TEX>

HILBERT-SCHMIDT INTERPOLATION ON AX = Y IN A TRIDIAGONAL ALGEBRA ALGL

한국수학교육학회지시리즈B:순수및응용수학 / Journal of the Korean Society of Mathematical Education Series B: Theoretical Mathematics and Pedagogical Mathematics, (P)3059-0604; (E)3059-1309
2008, v.15 no.4, pp.401-406
Kang, Joo-Ho (DEPARTMENT OF MATHEMATICS, DAEGU UNIVERSITY)

Abstract

Given operators X and Y acting on a separable complex Hilbert space H, an interpolating operator is a bounded operator A such that AX=Y. In this article, we investigate Hilbert-Schmidt interpolation problems for operators in a tridiagonal algebra and we get the following: Let <TEX>${\pounds}$</TEX> be a subspace lattice acting on a separable complex Hilbert space H and let X=<TEX>$(x_{ij})$</TEX> and Y=<TEX>$(y_{ij})$</TEX> be operators acting on H. Then the following are equivalent: (1) There exists a Hilbert-Schmidt operator <TEX>$A=(a_{ij})$</TEX> in Alg<TEX>${\pounds}$</TEX> such that AX=Y. (2) There is a bounded sequence <TEX>$\{{\alpha}_n\}$</TEX> in <TEX>$\mathbb{C}$</TEX> such that <TEX>${\sum}_{n=1}^{\infty}|{\alpha}_n|^2</TEX><TEX><</TEX><TEX>{\infty}$</TEX> and <TEX>

y1i=α1x1i+α2x2i
</TEX> <TEX>
y2ki=α4k1x2ki
</TEX> <TEX>
y{2k+1}_i={\alpha}_{4k}x_{2k}_i+{\alpha}_{4k+1}x_{2k+1}_i+{\alpha}_{4k+2}x_{2k+2}_i\;for\;all\;i,\;k\;\mathbb{N}
</TEX>.

keywords
Hilbert-Schmidt interpolation, CSL-algebra, tridiagonal algebra, Alg<tex> ${\pounds}$</tex>

한국수학교육학회지시리즈B:순수및응용수학