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Jan 24, 2010 at 1:46 comment added Jonas Meyer You are welcome to e-mail me (although I make no promises of time to think about this). But it is also typically considered reasonable, even encouraged, to add background to your question. In this case, I would think that people could better understand your problem if we knew what computing problem you are modeling, so it wouldn't be off topic to add that in my opinion.
Jan 24, 2010 at 1:15 comment added Daoud They could well do. The application is a very practical one in computing. The specific properties of the vector space are up for grabs - the main requirement is simply that we can compute the norm on the quotient algebra. If you're interested, perhaps we could discuss this via email, as I have a feeling we may have to go off-topic (I found your home page). Thanks again for your help.
Jan 23, 2010 at 23:44 comment added Jonas Meyer There is a reason I called that part of my answer "gratuitous". The construction came to mind and I couldn't resist mentioning it, but I had no reason to think it would have bearing on solving your problem. But perhaps the translated problem(s) would interest you too?
Jan 23, 2010 at 23:37 comment added Jonas Meyer I don't know a good reference for discussing this phenomenon in general, but the problem is this: Your problem is about a purely algebraic object, Q. If you translate the problem to a functional analysis problem (and it is not even clear to me what the best way to do that is), then it is a different problem that may not help you in your original problem. If you could find a way to embed Q faithfully in a quotient Banach algebra then you would get a norm, but this won't always be possible because in the Banach algebra quotient you mod out by a bigger ideal (that is the problem of closing).
Jan 23, 2010 at 23:10 comment added Daoud I'm afraid I didn't understand this part of your answer (I must confess I'm not a mathematician). Perhaps you could point me to a reference that would help me understand why closing causes such a problem.
Jan 23, 2010 at 23:06 comment added Jonas Meyer I don't see why you would necessarily want to throw in the annihilation operators; couldn't you work in non-self-adjoint algebras rather than C* algebras? In either case, to have a Banach algebra norm on the quotient you will need to close your tensor algebra and ideal, and I do not see how this will relate directly to the orginal construction.
Jan 23, 2010 at 22:31 history edited Daoud CC BY-SA 2.5
Exchange link that didn't work with a proper reference.
Jan 23, 2010 at 22:23 history answered Daoud CC BY-SA 2.5