假设H是一个复Hilbert空间,AH是H上的一个标准C*-代数,AH+是AH中所有正元构成的集合.1977年,Cuntz引入了C*-代数中正元的比较关系.设A是一个C*-代数,任给A,B∈A+,若存在X∈A+,使得A=XBX*,则记A≤B.文章刻画了定义在AH+上的所有双边保持此关系的弱连续半线性满射.
Let H be a complex Hilbert space,AH the standard C*-algebra on H,and AH+ the set of all positive elements in AH.In 1977,Cuntz introduced a comparison in the set of all positive elements in a C*-algebra.Let A be a C*-algebra.For A,B∈A+,we write A≤B if there exists an element X∈A such that A=XBX*.In this paper,we characterize all weakly continuous semilinear surjective maps on AH+ which preserves the positive elements comparison in both directions.