To remove a tellrat fact, the function untellrat needs the kernel. How is a user to
know the kernel? I was considering using tellrat in a little program for computing
eigenvectors, but I can't figure out how to remove tellrat facts.
(%i14) tellrat(x^2-x-13);
(%o14) [x^2-x-13]
(%i15) properties(x);
(%o15) []
(%i16) algebraic : true;
(%o16) true
(%i17) ratsimp(x^2-x-13);
(%o17) 0
The kernel *isn't x^2-x-13:
(%i18) untellrat(x^2-x-13);
(%o18) [x^2-x-13]
(%i19) ratsimp(x^2-x-13);
(%o19) 0
The kernel is x. But how is the user to know that?
(%i20) untellrat(x);
(%o20) []
(%i21) ratsimp(x^2-x-13);
(%o21) x^2-x-13
--Barton