On Thursday, September 17, 2015 at 2:54:15 AM UTC-7, Simon King wrote: > > The real problem here is that *conversion* gives rise to an error > that mentions *coercion*. > > sage: K.<x> = GF(25) > sage: L.<y> = GF(25) > sage: K(y) > Traceback (most recent call last): > ... > TypeError: unable to coerce from a finite field other than the prime > subfield > > That's clearly a bug. Conversion should work, even if it isn't canonical > and thus doesn't qualify as coercion! > I don't think it's "clearly a bug". Conversions are *allowed* to work when there is a non-canonical map (i.e., a section map back that's not a morphism, as for ZZ -> ZZ/p ) but I don't think conversions are *required* to work when such a map exists.
What would the condition be? That the minimal polynomials of x,y over GF(5) are identical? That the minimal poly of y has a root over K and then just choose a root (and let the conversion system try to keep things sane)? Do we expect for N.<a> = NumberField(x^5-x+1) M.<b> = NumberField(x^5 + 5*x^4 + 8*x^3 + 4*x^2 - 1) that N(b) should work? (there is actually less ambiguity there!) -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
