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Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics / Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics, (P)1226-0657; (E)2287-6081
1995, v.2 no.2, pp.91-95
Lee, Moo-Sang
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Abstract

Let H be an arbitrary complex Hilbert space and let (equation omitted)(H) be the *-algebra of all bounded linear operators on H. An operator T in (equation omitted)(H) is called normal if T<TEX>$\^$</TEX>*/T = TT<TEX>$\^$</TEX>*/, hyponormal if T<TEX>$\^$</TEX>*/T <TEX>$\geq$</TEX> TT<TEX>$\^$</TEX>*/, and quasi-hyponormal if T<TEX>$\^$</TEX>*/(T<TEX>$\^$</TEX>*/T - TT<TEX>$\^$</TEX>*/)A <TEX>$\geq$</TEX> 0, or equivalently ∥T<TEX>$\^$</TEX>*/T<TEX>$\chi$</TEX>∥ <TEX>$\leq$</TEX> ∥TT<TEX>$\chi$</TEX>∥ for all <TEX>$\chi$</TEX> in H.(omitted)

keywords

Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics