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Re: strange booleanconvert behavior?


Many thanks to Dave Snead and Peter Pein for their responses to my query about BooleanConvert behavior.

The solutions worked. At the same time, it is clear that BooleanConvert has a quirk (or the documentation is severely incomplete). Hope in version 9 it is fixed

Francisco

From: Dave Snead <dsnead6 at charter.net>
To: mathgroup at smc.vnet.net 
Sent: Wednesday, July 11, 2012 1:20 AM
Subject: [mg127374] Re: strange booleanconvert behavior?

Found the same problem.
Clearly Mathematica isn't working correctly when the number of sublists is 
more than 9.
As a work around consider

num1={{a,b,c,d},{a,b,c,e},{a,b,c,f},{a,b,c,g},{a,b,c,h},{a,b,c,i},{a,b,c,j},{a,b,c,k},{a,b,c,l},{a,b,c,m},{a,b,c,n}}
num2=Apply[Or,Apply[And,#]&/@num1]
x = BooleanConvert[Take[num2, 9], "CNF"];
y = BooleanConvert[Drop[num2, 9], "CNF"];
BooleanConvert[x || y, "CNF"]

Cheers,
Dave


-----Original Message----- 
From: Francisco Gutierrez
Sent: Monday, July 09, 2012 9:42 PM
To: mathgroup at smc.vnet.net
Subject: [mg127374] strange booleanconvert behavior?

Dear Group:
Say I have the following expression:
num1={{a,b,c,d},{a,b,c,e},{a,b,c,f},{a,b,c,g},{a,b,c,h},{a,b,c,i},{a,b,c,j},{a,b,c,k},{a,b,c,l},{a,b,c,m},{a,b,c,n}}


I transform it into a logical expression:
num2=Apply[Or,Apply[And,#]&/@num1]

I want to simplify this to a CNF, and the obvious function to use is Boolean 
Convert. Suppose I apply it to NINE elements of num2:
BooleanConvert[Take[num2,9],"CNF"]
The output is=

a&&b&&c&&(d||e||f||g||h||i||j||k||l)

It works perfectly well!


However, if I apply BooleanConvert to the whole expression I get back a 
bunch of crap. Also if I apply it to 10 elements of num2.
In sum, it appears that BooleanConvert only works well for 9 expressions or 
less. Tried this with other two examples, and found
exactly the same result.

All this in Mathematica 8

Can somebody help me?
Francisco


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