Bug report: I encountered some weird behavior in LaurentPolynomialRing, such as the nontransitivity of the '==' relation. Also, factoring in the fraction field caused an error. See below.
Feature request: I would like elements of the fraction field F of a Laurent polynomial ring S (say with base ring a field) to be able to tell if they are actually in S. If R is the polynomial ring underlying S then there should be a canonical isomorphism installed between F and the fraction field K of R. Since elements of K know when they are in R, an element of L can tell if it is in S by mapping itself to K and checking whether its denominator is a monomial. More generally, if S is any integral domain with fraction field F, I would like to have the option of equipping the pair (S,F) with methods that can detect whether an element of F is in S, and the ability to compute the quotient of elements of S and return an element of S if the answer is indeed in S and not just F. --------- Sage Version 5.0.beta7, Release Date: 2012-03-05 Current Mercurial branch is: combinat sage: S = LaurentPolynomialRing(QQ,['x']) sage: F = S.fraction_field() sage: R = S.polynomial_ring() sage: K = R.fraction_field() sage: F == K False sage: R.gen(0) == S.gen(0) True sage: 1/R.gen(0) == 1/S.gen(0) True sage: 1/S.gen(0) == (S.gen(0))^(-1) True sage: 1/R.gen(0) == (S.gen(0))^(-1) False # What!?? sage: R.gen(0)^(-1) in S False sage: S.gen(0)^(-1) in S True sage: 1/S.gen(0) in S False sage: (1/R.gen(0)).factor() x^(-1) sage: (1/S.gen(0)).factor() Traceback (most recent call last) ... AttributeError: 'sage.rings.integer.Integer' object has no attribute 'dict' -- 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
