一类缺项算子矩阵正补的谱刻画

On the spectra of positive completions for some operator partial matrices

对 于 具 有 离 散 谱 的 正 算 子 Ａ， Ｂ， 我 们 给 出 了 一 个 闭 集 成 为 ２ × ２ 缺 项 算 子 矩 阵 Ａ ？？ Ｂ 的某个正 补的谱的一些

Let A and B be given positive operators acting on suitable complex Hibert spaces. Several conditions which assure a closed subset of nonnegative numbers to be the spectrum of some positive completion of 2 by 2 operator partial matrices of the form A? ?B are presented.