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Jul 9, 2012 at 10:52 history undeleted Marc Palm
Jul 9, 2012 at 8:48 history deleted Marc Palm
Jul 8, 2012 at 22:31 comment added Marc Palm Smooth vectors of representation on locally convex spaces are always dense. I am not taking inverse of $\phi$, since $\phi$ is not surjective. We take a closure. Smooth vectors are a dense proper subset. I am only claiming that for two unitarization, you get a densely defined (on smooth vectors), closed operator between them, and that this is all you need. But I don't know the proof, but that is how it appears plausible. The facts remain true and are not my observations. Sorry that I do not remember a reference for this. I come back when I find the time. Best, Marc
Jul 8, 2012 at 19:43 comment added Bugs Bunny I meant $\phi^{-1}(V)\cap V$... as we have $\phi^{-1}(V)\cap V\rightarrow V$... but from what I can see we can just have $\phi^{-1}(V)\cap V=0$, why not??
Jul 8, 2012 at 19:36 comment added Bugs Bunny And you cannot really work with $\overline{V}_{<,>}$ because to extend $(,)$ to this completion you really need to show that the norms are equivalent...
Jul 8, 2012 at 19:33 comment added Bugs Bunny Still not sure. Let me get my head around $S_1$ and $S_2$ first. The crucial intertwiner $\phi$ is defined $V\rightarrow \overline{V}_{<,>}$, the completion with respect to $<,>$. Are you saying that $\phi^{-1} (V)$ is dense in $V$? O'why could that be true?
Jul 8, 2012 at 17:18 comment added Marc Palm equal should mean bijective on objects and morphisms
Jul 8, 2012 at 17:17 comment added Marc Palm Sorry $S_1$ is equal to $S_2$.
Jul 8, 2012 at 17:16 comment added Marc Palm For $1$: Schur's lemma holds for densely-defined, closed intertwiner. Use the graph norm for extending Schur's lemma. For $2$: There is no nice correspondance between the categories $S_1$ and $S_3$. If you change the equivalence on the Hilbert-reps. to Naimark equivalence, then $S_1$ is contained in $S_3$ and $S_1$ is equal to $S_3$. I am not sure what the correct category terms are here, but I guess you understand what I want to say. Note that there exists unbounded intertwiner between non-unitarizable principal series representations.
Jul 8, 2012 at 15:50 comment added Bugs Bunny I am less certain what you are saying about $C$. All admissible irreducible reps are smooth and some are not unitarizable, as sure as devine carrots. How does it give a rep in $S_3$, not in $C(S_2)$? I am kind of thinking that $C$ is not surjective, but this should come from a representation on a Hilbert space without any nonzero smooth vectors!! I think $C$ is injective but again one needs to argue why two different reps cannot have isomorphic completions. This should correspond to "too many" smooth vectors forming a reducible representation...
Jul 8, 2012 at 15:36 comment added Bugs Bunny Thanks! Unfortunately, you have neither explained, nor given any references. Say, the standard proof of uniqueness of the unitary structure in the finite dimensional case goes via a morphism $\phi$ defined by $<\phi (x),y> = (x,y)$ and the endomorphism property $End (V)={\mathbb C}$. Here one has the endomorphism property, indeed, but I do not understand why $\phi$ is well-defined!! Essentially, so defined $\phi (x)$ is an element of the complection, and not necessarily of the original representation. How do you go around it?
Jul 8, 2012 at 9:31 history edited Marc Palm CC BY-SA 3.0
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Jul 8, 2012 at 8:51 comment added Marc Palm Btw, either unitarizable smooth or unitary. Unitary is the completed stuff, which does not preserve smoothness, and the smooth vectors are almost never a Hilbert space, at most a pre-Hilbert space.
Jul 8, 2012 at 8:46 comment added Marc Palm Steinberg=special.
Jul 8, 2012 at 8:43 history edited Marc Palm CC BY-SA 3.0
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Jul 8, 2012 at 8:35 history answered Marc Palm CC BY-SA 3.0