I don't think we'll ever get SR to operate properly in positive characteristics; especially because it would allow completely arbitrary characteristic combinations in the first place, but perhaps the cases below help in tracking down if we can so something to improve the situation a bit:
sage: ((1)*((1)*x+(1)/x)^3+(1)).expand() x^3 + 3*x + 3/x + 1/x^3 + 1 sage: ((k(1)*x+k(1)/x)^3+k(1)).expand() x^3 + 3*x + 3/x + 1/x^3 + 1 sage: (k(1)*(k(1)*x+k(1)/x)^3).expand() x^3 + 1/x^3 sage: (k(1)*(k(1)*x+k(1)/x)^3+k(1)).expand() 0/x + 1/x^3 + 1 sage: ((k(1)*x+k(1)/x)^3+k(1)).expand() x^3 + 3*x + 3/x + 1/x^3 + 1 so it's the combination of multiplying the third power by k(1) and adding k(1) to it that leads "expand" to producing an expression that is really invalid. My guess is that it finds a nonzero factor 3 somewhere, which it assumes is invertible, and ends up multiplying both numerator and denominator of some fraction somewhere. The numerator ends up being combined in GF(3), so that one gets 0 and SR takes it happily from there, removing the factor 3 from the denominator again. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
