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

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94842] Re: [mg94828] How to get rid of irrelevant Boolean variables from an expression
  • From: "David Park" <djmpark at comcast.net>
  • Date: Mon, 29 Dec 2008 06:34:09 -0500 (EST)
  • References: <16579154.1230380168937.JavaMail.root@m02>

LogicalExpand ??


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  


From: Vlad [mailto:vladtarko at gmail.com] 


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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