1 | initial version |

Please format your question, it is almost impossible to guess what your question is.

to me, it seems that you have defined the fraction field but have not defined the "variables". You should do

F.<x,y>=Frac(k['x,y'])

or

F=Frac(k['x,y']) x,y=F.gens()

Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.