
Re: strange booleanconvert behavior?
Posted:
Jul 20, 2012 3:57 AM


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@charter.net> Sent: Wednesday, July 11, 2012 1:20 AM Subject: 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 Subject: 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&&(defghijkl)
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

