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Re: How to get rid of irrelevant Boolean variables from

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94878] Re: [mg94828] How to get rid of irrelevant Boolean variables from
  • From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
  • Date: Mon, 29 Dec 2008 06:40:41 -0500 (EST)
  • References: <200812271204.HAA12519@smc.vnet.net>

Hi,

maybe Mathematica doesn't assume that x and y are booleans?

FullSimplify[(x && y) || ( ! x && y), 
   Assumptions -> Element[{x, y}, Booleans]]

Cheers
Patrick


On Sat, 2008-12-27 at 07:04 -0500, 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
> 



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