On 2020-03-07, Eric Gourgoulhon <egourgoul...@gmail.com> wrote: > You should use simplify_full() instead of simplify():
Or you should rather use *polynomials* instead of general symbolic variables, provided of course that all your expressions are multivariate rational functions (which is the case here): > sage: var('s t') > (s, t) sage: R.<s,t> = QQ[] > sage: thirdroot = ((s^2 - 1)*t^2 - s^2 + 1)/(s^2 + 2*s*t + t^2) sage: thirdroot = ((s^2 - 1)*t^2 - s^2 + 1)/(s^2 + 2*s*t + t^2) > sage: factor(thirdroot + 1) > (s*t + 1)^2/(s + t)^2 sage: factor(thirdroot + 1) (s + t)^-2 * (s*t + 1)^2 > sage: a = thirdroot + 1 - (s*t + 1)^2/(s+t)^2 > sage: a > ((s^2 - 1)*t^2 - s^2 + 1)/(s^2 + 2*s*t + t^2) - (s*t + 1)^2/(s + t)^2 + 1 > sage: a.simplify_full() > 0 sage: a = thirdroot + 1 - (s*t + 1)^2/(s+t)^2; a 0 That's because thirdroot is an element of the quotient field of a polynomial ring, which does automatic simplifications (which in the special context of polynomials is a lot easier than in the general context of symbolic variables). Best regards, Simon -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/r40ug5%241rii%241%40ciao.gmane.io.