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May 2, 2016 at 19:53 comment added Johannes Hahn @AliTaghavi Well, yes for simple tensors this is a valid definition. But then you have only defined $t\otimes T$ on the algebraic tensor product which is a dense subspace of the/any C*-algebra-tensor product. You need some form of continuity to extend this maps from the subspace to the whole space.
May 2, 2016 at 15:59 comment added Ali Taghavi @UlrichPennig thanks very much for your very helpful comment.
May 2, 2016 at 15:37 comment added Ali Taghavi @WillSawin Thank you for this very interesting point. Your comment is interesting and is a motivation to ask: How many isomorphisms between $\mathcal{K} $ and $\mathcal{K} \otimes \mathcal{K}$ are there?Some isomorphisms diffrent from "matrix tensor product?
May 2, 2016 at 15:09 comment added Ali Taghavi @JohannesHahn Thanks for your comment. For two element $a,b$ $T(a)\otimes T(b)$ is defined simply as a "simple tensor", so I think that the definition does mot need bounded ness of $T$.Am I right?
Apr 30, 2016 at 20:11 comment added Johannes Hahn How do you define $T\otimes T$ on $A\otimes A$ without using boundedness in the first place? Remember that $A\otimes A$ is a completion of the algebraic tensor product and therefore you need some form of continuity to extend operators from the algebraic to the spatial tensor product.
Apr 30, 2016 at 20:07 comment added Ulrich Pennig btw. the only scalars that satisfy your condition are $0$ and $1$, since the first equation gives you $\lambda = \lambda^2$.
Apr 30, 2016 at 20:04 comment added Ulrich Pennig The property $A \cong A \otimes A$ is called self-absorbing. So-called strongly self-absorbing $C^*$-algebras have played a cornerstone role in the classification program.
Apr 30, 2016 at 18:25 comment added Will Sawin Don't you think this could depend on the choice of isomorphism between $A$ and $A \otimes A$?
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Apr 29, 2016 at 15:29 history asked Ali Taghavi CC BY-SA 3.0