How to define tensor product of algebras (and make it an algebra)
I'm in my first week of Sage (also new to Python). Aiming at symbolic calculations, suppose I have an associative algebra A (think of the Clifford algebra, or the free algebra, for concreteness).
In particular A is a vector space, and I'd like to define a tensor product A⊗A. I've seen that tensor algebra is implemented in SageMath, but I only need two factors, and anyway, I'd like to make A⊗A an algebra in a way that is not endowed with the obvious product (a⊗b)⋅(c⊗d)=ac⊗bd. (Ideally, the final algebra will depend on a state on A, but for simplicity think of my product being, say, (a⊗b)⋅(c⊗d)=ac⊗db.)
An example of how to do what I wish (although not precisely the same object), is along the lines of Mathematica Stack Exchange answer 165511:
CenterDot[X___, Y_Plus, Z___] := CenterDot[X, #, Z] & /@ Y (* additivity *)
CenterDot[] = 1;
CenterDot[X_] := X
CenterDot[X___, 1, Y___] := CenterDot[X, Y] (* unital*)
SetAttributes[CenterDot, Flat] (* associativity *)
This allows to create a product CenterDot
that behaves as it should. But in SageMath I need to define the analogue of this on A⊗A and this is not even clear to me how to define this product. (I.e. if it's not implemented, I probably should do something analogous to the code above, first for ⊗, tell it that it has to be bilinear, etc.)
Welcome to Ask Sage! Thank you for your question.