Approximation by positive operators. (English) Zbl 0243.47026
MSC:
47L07 | Convex sets and cones of operators |
41A35 | Approximation by operators (in particular, by integral operators) |
41A50 | Best approximation, Chebyshev systems |
References:
[1] | Berberian, S.K.: Approximate proper vectors. Proc. Amer. math. Soc.13, 111-114 (1962). · Zbl 0166.40503 · doi:10.1090/S0002-9939-1962-0133690-8 |
[2] | Bouldin, R.: Positive approximants. Trans. Amer. math. Soc. (to appear). · Zbl 0264.47020 |
[3] | Douglas, R.G.: On majorization, factorization and range inclusion of operators in Hilbert space. Proc. Amer. math. Soc.17, 412-416 (1966). |
[4] | Halmos, P.R.: Positive approximants of operators. Indiana Univ. math. J.21, 951-961 (1972). · Zbl 0263.47018 · doi:10.1512/iumj.1972.21.21076 |
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