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Jun 18, 2023 at 4:59 vote accept Nanoputian
Jun 17, 2023 at 14:46 history became hot network question
Jun 17, 2023 at 14:29 answer added Tom Goodwillie timeline score: 7
Jun 17, 2023 at 13:52 answer added Benjamin Steinberg timeline score: 10
Jun 17, 2023 at 13:18 comment added Benjamin Steinberg There are lots of semigroup examples.
Jun 17, 2023 at 13:12 comment added Tom Goodwillie I'm not sure about my example, but I'll think about finding another, if nobody else gives one.
Jun 17, 2023 at 11:58 comment added Nanoputian @TomGoodwillie Yes that is what I mean. If you write the counterexample as an answer I will be happy to accept it.
Jun 17, 2023 at 11:17 comment added Tom Goodwillie About Dave Benson's question, presumably you mean that the coproduct of a generator $x$ is $x\otimes x$, in other words a generator operates on $V\otimes W$ by $x(v\otimes w)=xv\otimes xw$. Assuming this, there is a counterexample in which $A$ is free on two generators and $V=W$ is $2$-dimensional.
Jun 17, 2023 at 9:30 comment added Dave Benson What is your coproduct on the free algebra?
Jun 17, 2023 at 8:02 comment added Nanoputian @Mare Sorry, I have realised that the tensor product is not in general defined for algebras. So to be more specific, the case I am interested in is when $A$ is the free algebra generated by $n$ elements (even $n = 2$ case is fine). Though, perhaps its too much to ask for such a specific case to have been treated in the literature.
Jun 17, 2023 at 7:58 history edited Nanoputian CC BY-SA 4.0
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Jun 17, 2023 at 7:44 comment added abx Indeed in characteristic 0, $V\otimes W$ is semi-simple as a $A\otimes A^{op}$-module.
Jun 17, 2023 at 7:01 comment added Mare What is the $A$-module strucutre on $V \otimes W$? If it is not a Hopf algebra this might not be so canonical. Or do you view $V \otimes W$ as a module over the enveloping algebra $A \otimes A^{op}$ of $A$?
Jun 17, 2023 at 6:46 history asked Nanoputian CC BY-SA 4.0