User talk:Duffifi

Hello world!

TakuyaMurata, regarding the edit at Normal operator, I did not understand the claim that $\langle Sx,x\rangle =\langle Tx,x\rangle$ implies $S=T$. It seems blatantly wrong in the case of real Hilbert spaces, for example, since there we have $\langle Sx,x\rangle =\langle S^{*}x,x\rangle$ for any operator $S$.

I have moved the discussion at my talkpage to that of [[normal operator], with some additional comment. -- Taku (talk) 01:33, 8 August 2009 (UTC)