Hi, I was recently at a Sage workshop, some of my notes here: http://ondrejcertik.blogspot.com/2007/11/sage-days-6.html and there we also discussed sympy and ginac and licensing issues and we came to the conclusion, that just by copying a C++ code to Python (by hand) is a derived work. That's what I did at the beginning - I used the same class structure and copied some of the algorithms from ginac. Ginac is GPL and sympy used to be too, so far so good. But then, we decided to use BSD, because it's more free and we think it's just better for sympy. However, we now changed almost everything in sympy, just the class structure stayed - but I mean - it's just a class structure (even that is not 100% the same, we don't use ex for example). So I wanted to clarify with you, if it's ok, if we use BSD for sympy. Thanks, Ondrej