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Re: How to get rid of irrelevant Boolean variables from

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94891] Re: [mg94828] How to get rid of irrelevant Boolean variables from
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Mon, 29 Dec 2008 06:43:01 -0500 (EST)
  • Reply-to: hanlonr at cox.net

expr = x && y || ! x && y;

expr // LogicalExpand

y



Bob Hanlon


On Sat, Dec 27, 2008 at 9:35 AM , 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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