On Mon, Nov 21, 2011 at 11:36 PM, William Stein <wst...@gmail.com> wrote: > On Mon, Nov 21, 2011 at 4:50 PM, David Roe <r...@math.harvard.edu> wrote: >> The coercion graph in Sage is supposed to be transitive. This >> assumption is explicit in the documentation of sage.structure.coerce >> for example. But we have the following: >> >> sage: R = Zmod(6) >> sage: S = Zmod(3) >> sage: T = GF(3) >> sage: T.has_coerce_map_from(S) >> True >> sage: S.has_coerce_map_from(R) >> True >> sage: T.has_coerce_map_from(R) >> False > > I think that should return True, since there is a canonical map from > Z/6Z to GF(3). > >> Any opinions on which of these results should change? I'm thinking >> about such coercions between finite rings in the context of residue >> fields and quotients of p-adic rings, so you can also ask yourself if >> you want a coercion from Zmod(250) to Zp(5).quotient(5^3). > > I want such a coercion, since again there is a canonical map Z/250Z > --> Z/5^3Z \isom Z_5 / 5^3 Z_5.
+1. My thoughts exactly. - Robert -- 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
