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Re: How to get rid of irrelevant Boolean variables from an expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94861] Re: How to get rid of irrelevant Boolean variables from an expression
  • From: David Bailey <dave at removedbailey.co.uk>
  • Date: Mon, 29 Dec 2008 06:37:36 -0500 (EST)
  • References: <gj55j3$c60$1@smc.vnet.net>

Vlad wrote:
> Hi,
> 
> I need to simplify a Boolean expression that looks like
> 
> x && y || !x && y
> 
> to y alone. I.e. the expression's truth value is independent of x so it should be left out.
> 
> I've tried about every Mathematica function for dealing with Boolean expressions and couldn't do this. Also,
> 
> Equivalent[x && y || !x && y, y]//TautologyQ 
> 
> gives False. This might be because the two expressions don't have the same number of variables (?). 
> 
> I have large truth tables so I would like to get rid of the irrelevant Boolean variables automatically. Does anyone know how to do this?
> 
> Thanks
> 
x && y || ! x && y // FullSimplify

y

David Bailey
http://www.dbaileyconsultancy.co.uk


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