Re: How to solve system of inequalities?

*To*: mathgroup at christensen.cybernetics.net*Subject*: [mg1102] Re: How to solve system of inequalities?*From*: gwyn at arl.mil (Doug Gwyn )*Date*: Sun, 14 May 1995 23:01:36 -0400*Organization*: U.S. Army Research Laboratory APG, MD.

In article <3oker8$jh7 at news0.cybernetics.net>, jeff at econ.berkeley.edu wrote: ->Hi. I have a system of linear inequlities specified symbolically. ->I want to test whether they are consistent. ->But if I enter -> In[2] y<x && x<y ->I get back the unhelpful -> Out[2] y < x && x < y ->Apparently Mathematica cannot deduce that this is impossible. I'm pretty sure the *general* question is not effectively computable. If the specific need is for a chain of simple variables as above and not more complicated expressions, then this becomes a well-ordering issue and what *I* would do to solve it would be to use UNIX "tsort", or if it had to be in Mathematica I'd implement a topological sorting algorithm.