数学杂志2026，Vol.46Issue(2)：120-124,5.
压缩秩1投影对联合数值域的映射
MAPPINGS SHRINKING THE JOINT NUMERICAL RANGE OF ANY PAIR OF RANK 1 PROJECTIONS
摘要
Abstract
This paper characterizes the map Φ which shrinks the joint numerical range of any pair of rank 1 projections.By using the intrinsic properties of the joint numerical range of pairs of projections,this paper demonstrates that Φ preserves orthogonality in both directions andΦ preserves the joint numerical range of any pair of rank 1 projections when the Hilbert space is two-dimensional.It follows that a surjective mapping shrinking the joint numerical range of any pair of rank 1 projections is induced by a unitary or anti-unitary operator,thereby generalizing the results of Deng Nian,Qian Wenhua,and Wu Wenming on mappings that preserve the joint numerical range of any pair of rank 1 projections on finite-dimensional Hilbert spaces.关键词
投影对/压缩联合数值域/酉算子/反酉算子Key words
pair of projection/shrinking joint numerical range/unitary/anti-unitary分类
数理科学引用本文复制引用
李阳,陈少波..压缩秩1投影对联合数值域的映射[J].数学杂志,2026,46(2):120-124,5.基金项目
重庆市自然科学基金资助(CSTB2025NSCQLZX0057). （CSTB2025NSCQLZX0057）
