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Mar 21, 2021 at 13:56 comment added user167952 Nice argument. Thanks again.
Mar 21, 2021 at 13:38 comment added Stefaan Vaes Let $\pi : B \to A$ be any surjective $*$-homomorphism between unital C$^*$-algebras and $\omega$ a state on $A$. Put $\varphi = \omega \circ \pi$. Since $\omega(\pi(a)^* \pi(b)) = \varphi(a^* b)$, there is a canonical unitary identification between the GNS-Hilbert spaces of $\omega$ and $\varphi$. This unitary implements the isomorphism between $\pi_\omega(A)$ and $\pi_\varphi(B)$.
Mar 21, 2021 at 13:31 history rollback Stefaan Vaes
Rollback to Revision 1
S Mar 21, 2021 at 13:30 history suggested user167952 CC BY-SA 4.0
Fixed a typo.
Mar 21, 2021 at 13:23 comment added user167952 Maybe one additional question: we want to define $\theta(\pi_B(b)) = \pi_A(\pi(b))$. Why is this well-defined? If $\pi_B(b) = 0$, then $0=h_B(b) = h_A\circ \pi(b)= \langle \pi_A\pi(b)\xi_A, \xi_A\rangle$ but how can we conclude that $\pi_A(\pi(b)) = 0$?
Mar 21, 2021 at 11:07 review Suggested edits
S Mar 21, 2021 at 13:30
Mar 21, 2021 at 10:52 vote accept CommunityBot
Mar 21, 2021 at 10:52 comment added user167952 Thank you professor Vaes. This is exactly what I'm looking for.
Mar 21, 2021 at 9:22 history answered Stefaan Vaes CC BY-SA 4.0