Re: Full adder

Posted by cadet1620 on Feb 06, 2013; 3:57pm
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Full-adder-tp4026235p4026242.html

joobcode wrote

You mention ~(A(~B)) which I read as:

Not( And(A, Not(B) ))

I ask for your working because I can't see this directly in the term I want to reduce or how to derive this from the term I am trying to reduce.

It has occurred to me that I might not be using the correct conventions for expressing this term with plain text. So here is the term I trying to reduce in postfix notation.

And(C, Or( And(Not(A),B), And(A, Not(B) ) ) )

Your notation is OK.

To use x + ~x = 1 to reduce the above, And(Not(A),B) and And(A,Not(B)) must be logical inverses. In other words,
    And(Not(A),B) = Not(And(A,Not(B)))
must be true. It is not. Use truth tables to compare them.

--Mark