Re: Assume and $Assumptions and Results

*To*: mathgroup at smc.vnet.net*Subject*: [mg102247] Re: [mg102216] Assume and $Assumptions and Results*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sun, 2 Aug 2009 06:02:12 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200908010802.EAA07200@smc.vnet.net>*Reply-to*: murray at math.umass.edu

Unless x already has a specific numeric value, the correct result of Simplify[x > 1, x > 0] is: x > 1 This result is the same as that of: Simplify[x > 1 && x > 0] It would be redundant to include Element[x,Reals], since x > 0 already implies that. ivo welch wrote: > [Easy Beginner's Query] > > > Dear Experts: > > My goal is to input a set of assumptions for various variables, and then > determine whether an expression of these variables (a long derivative that > is a few lines) is true or false. That is, I want to input many conditions, > such as "$Assumptions = (x>y) && (y>1)" and then ask Mathematica whether "1/(X+Y) > > 1.5" is true, for example. > > Alas, I am a little stuck on home plate: > Simplify[ x > 1, x>0 ] > given that x is greater than 0, isn't it supposed to be True? Instead Mathematica > returns "x>1". It also does not help to make the condition "(x > <esc>elem<esc> Reals) && (x>0)" . > > > (Another brief questions: do $Assumptions assignments add or replace > earlier assumptions?) > > > Help appreciated. Am I expecting too much of Mathematica? > > /iaw > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Assume and $Assumptions and Results***From:*ivo welch <ivowel@gmail.com>