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New Boolean algebra
I'm having a problem distilling down a boolean expression.

Here it is:
(ab + ab' + a'b)'\n= (ab)'(ab')'(a'b)'\n= (a' + b')(a' + b)(a + b')\n= (a' + b'b)(a + b'\n= a'(a + b')\n= a'a + a'b'\n= a'b'
Is this correct? I'm having a hard time in that when I take different approaches to the problem, I'm getting different answers which don't seem compatible.

--\n-------------------------------------------------------------------\n* Jack Troughton                            jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca]                   [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada               [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
New b' == not b ?
--

The rich, as usual, are employing the elected.
-- [link|http://unfit2print.blogspot.com/|http://unfit2print.blogspot.com/]
New Yes.
--\n-------------------------------------------------------------------\n* Jack Troughton                            jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca]                   [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada               [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
New Re: Boolean algebra
The conclusion seems to be correct, as evident from the truth tables:

Original expression, first term makes it false for 11, second for 10 and third for 01.
For 00, the original gives true.

so, reduction to a'b' is justified


(a' + b')(a' + b)(a + b') =

(a' + b'a' + a'b + b'b)(a + b') =

(a' + b'a' + a'b + 0) =

(a' + b'a' + a'b)(a + b') =

a'a + b'a'a + a'ba + a'b' + b'a'b' + a'bb' =

0 + 0 + 0 + a'b' + b'a' + 0 = a'b' + a'b' =

a'b'
--

The rich, as usual, are employing the elected.
-- [link|http://unfit2print.blogspot.com/|http://unfit2print.blogspot.com/]
New Well, it was my leading candidate
for the right answer;)

Weird... when I write it down w/ pen and paper, I get all screwed up, but as soon as I'm typing it, it becomes a lot clearer. The mind works in mysterious ways...

Thanks.
--\n-------------------------------------------------------------------\n* Jack Troughton                            jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca]                   [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada               [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
New If you use a Karnaugh map, you'll see you're OK.
[link|http://www.ee.surrey.ac.uk/Projects/Labview/minimisation/karnaugh.html|Karnaugh map]. It's a two dimensional representation of a truth table.

The "sum of products" form is the easiest for filling out Karnaugh maps.

Using your first expression but ignoring the outer negation:

    a' a

b'  0  1
b   1  1

negating flips all bits

    a' a

b'  1  0
b   0  0


So, indeed it's a'b'.
Alex

"Propaganda does not deceive people; it merely helps them to deceive themselves." -- Eric Hoffer
Expand Edited by a6l6e6x Dec. 3, 2003, 03:56:56 PM EST
New Speaking of which
there's [link|http://www.embedded.com/showArticle.jhtml?articleID=16100908|A primer on Karnaugh maps] over on Embedded Systems that might be of interest.
Expand Edited by ChrisR Dec. 3, 2003, 03:41:29 PM EST
New Speaking of which^2
that's part 2 of the assignment:)
--\n-------------------------------------------------------------------\n* Jack Troughton                            jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca]                   [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada               [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
     Boolean algebra - (jake123) - (7)
         b' == not b ? -NT - (Arkadiy) - (1)
             Yes. -NT - (jake123)
         Re: Boolean algebra - (Arkadiy) - (1)
             Well, it was my leading candidate - (jake123)
         If you use a Karnaugh map, you'll see you're OK. - (a6l6e6x) - (2)
             Speaking of which - (ChrisR) - (1)
                 Speaking of which^2 - (jake123)

The pursuit of balance can create imbalance because sometimes something is true.
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