For the record, we had proposed in #18675 to refer to the "graded Hopf 
algebra" that the topologists use as GradedTopologicalHopfAlgebras and to 
refer to "Hopf algebras with a grading" that combinatorialists use as 
GradedCombinatorialHopfAlgebras.  It comes up in a name choice in an 
example in that ticket.

I mainly wanted to know if the current GradedHopfAlgebra structure could 
handle the two types.

If it were just a matter of tests, then *I think* the answer is yes, 
however then Jean-Baptiste pointed out to me the following example:

sage: R = NonCommutativeSymmetricFunctions(QQ).R()

sage: (tensor([R[1],R[[]]])+tensor([R[[]],R[1]]))^2

R[] # R[1, 1] + R[] # R[2] + 2*R[1] # R[1] + R[1, 1] # R[] + R[2] # R[]
This product is built into the tensor code.  It implies that 
(A # B) * (C # D) = (\mu \otimes \mu) \circ (id \otimes \tau \otimes \tau) 
(A # B # C # D)
where \tau( B # C ) = C # B.  I think this is not what we expect for a 
GradedTopologicalHopfAlgebras, but I guess that the product on the tensor 
space could be overwritten for those examples.

-Mike





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