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Re: SatisfiabilityInstances[] how to put variables

  • To: mathgroup at smc.vnet.net
  • Subject: [mg128370] Re: SatisfiabilityInstances[] how to put variables
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Wed, 10 Oct 2012 01:26:33 -0400 (EDT)
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  • References: <20121009044008.1114F68DF@smc.vnet.net>

eqns = {x^2 + Pi*y^2 + z^2 == -1, z^2 == 2 x*E - 5 y};

var = Cases[eqns,
   x_Symbol?(! NumericQ[#] &), Infinity] //
  Union

{x, y, z}


Bob Hanlon


On Tue, Oct 9, 2012 at 12:40 AM,  <info at dvholten.de> wrote:
> folks,
> i am playing with the satisfiability-support in Mathematica.
> SatisfiabilityInstances[] gives me the settings of the variables, which return true for the whole formula. However, the input is a little uncomfortable:
> SatisfiabilityInstances[ formulaCNF, { v1, v2, v3, v4, v5 } ]
> needs to be called for a formula with the 5 variabled v1..v5. For a formula with 400 variables this is not practical.
> is there short way to extract a list of variables from the formula?
> is there a short way to build a list of variables names?
> (assuming the variables are named as a sequence like x1, x2...x77 or var1...var999).
> or is there a way to implictily tell SatisfiabilityInstances[] or one of his brothers what the variables are in the formula so that they dont have to be given one by one?
>
> thanks
> DvH
>



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