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Simplifying inequalities

  • To: mathgroup at smc.vnet.net
  • Subject: [mg36790] Simplifying inequalities
  • From: Vincent Bouchard <bouchard at maths.ox.ac.uk>
  • Date: Wed, 25 Sep 2002 01:51:39 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I have a set of inequalities that I solve with InequalitySolve. But then
it gives a complete set of solutions, but not in the way I would like it
to be! :-) For example, the simple following calculation will give:

In[1]:= ineq = {y4 >= -1, y5 >= -1, y6 + y4 >= y5 - 1, y5 >= y6, y6 >= -1};
	InequalitySolve[ineq,{y4,y6,y5}]

Out[1]:= y4 == -1 && y6 >= -1 && y5 == y6 ||
  y4 > -1 && y6 >= -1 && y6 <= y5 <= 1 + y4 + y6

the result is good, but I would like it to be in the simpler but
equivalent form

  y4 >= -1 && y6 >= -1 && y6 <= y5 <= 1 + y4 + y6

How can I tell InequalitySolve to do that? It is simple for this example,
but for a large set of simple inequalities InequalitySolve gives lines and
lines of results instead of a simple result.

Thanks,

Vincent Bouchard
DPHil student in theoretical physics in University of Oxford



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