I have a set of variables x1,...,xn and y1,...,ym for n,m>=1.
Now I can build all quadratic monomials of the form xiyj and yjxi (but we do not have xiyj=yjxi as we calcualte in the non-commutative polynomial ring). But something like xixj is not allowed as after an xi there must come and yj and after an yi there must come an xi.
Now I want with Sage the list of all possible relations of the form w1±w2±w3⋯ such that all wi are different quadratic relations that all start either with a xi or a yj.
For example for n=2 and m=1, possible relations are (I hope I did not forget any relation) : x1y1,x1y1−x2y2,x1y2+x2y2,x2y1,y1x1,y1x2,y1x1−y1x2,y1x1+y1x2.
I am not sure how to do this in an easy way with Sage, but maybe someone knows a simple trick.
Thanks for any help.