certainly, we do not really want Fraction from Fields, but where (certainly not in algebra) is this kind of knowledge hidden in AXIOM?
one would suspect that Fraction could be defined in an algebraic was, something like Fraction F: F : IntegralDomain not Field In any case, AXIOM should be consistant: )sh Fraction Fraction Integer gives a valid answer. In order to get Fractions from RADIX 2 - only considering RADIX 2 as an IntegralDomain an not to build new constructors, one should have a forgetful functor. Am 04.10.2012 um 13:10 schrieb Ralf Hemmecke: >> (3) -> F2 := Fraction RADIX 2 >> >> (3) Fraction(RadixExpansion(2)) >> > Type: Type >> (4) -> a :: F2 >> >> Fraction(RadixExpansion(2)) is not a valid type. > > I don't know exactly which code part triggers this error, but I guess, > it's the same as with the following. > > (2) -> Q := Fraction Integer > > (2) Fraction(Integer) > Type: > Type > (3) -> Q has IntegralDomain > > (3) true > Type: > Boolean > (5) -> F := Fraction Q > > (5) Fraction(Fraction(Integer)) > Type: > Type > (6) -> f: F := 1 > > Fraction(Fraction(Integer)) is not a valid type. > > I've found an older thread where similar things where discussed. > > http://lists.nongnu.org/archive/html/axiom-developer/2006-09/msg00570.html > > The problem in your case probably is that > > (6) -> RadixExpansion 2 has Field > > (6) true > > and that the interpreter doesn't want to construct a Fraction over a > field. Whether that's good or bad, is to be discussed. > > Ralf > > -- > You received this message because you are subscribed to the Google Groups > "FriCAS - computer algebra system" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/fricas-devel?hl=en. > Mit freundlichen Grüßen Johannes Grabmeier Prof. Dr. Johannes Grabmeier Köckstraße 1, D-94469 Deggendorf Tel. +49-(0)-991-2979584, Tel. +49-(0)-171-5503789 Tel. +49-(0)-991-3615-100 (d), Fax: +49-(0)-1803-5518-17745 -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/fricas-devel?hl=en.
