Hi! I am currently overhauling the code for Infinite Polynomial Rings, trying to introduce construction functors for it.
At this occasion, I found that the composition of ConstructionFunctors is broken. Namely, for construction functors F1 and F2, there are two conventions of what F1*F2 should do: F1*F2(X)=F2(F1(X)) or F1*F2(X)=F1(F2(X)). Unfortunately, *both* conventions are used in sage.categories.pushout at the same time. Moreover, prod(F.expand()) is generally not equal to F (I think "it should be equal" is a reasonable requirement). I created the ticket http://trac.sagemath.org/sage_trac/ticket/7620 for it. Since F1*F2(X)=F1(F2(X)) is used by the default multiplication method of ConstructionFunctor, I suppose that this is the *official* Sage convention (and happens to be my personal preference, too). So, I changed CompositConstructionFunctor since it does not follow that convention. I also changed the expand method so that prod(F.expand ()) is equal to F. I post here since I wonder whether a voting on the convention is necessary? And of course the ticket needs a reviewer... Best regards, Simon -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
