Expanding out PoS to SoP

Hi there,


I'm running through an exercise where I have to expand the PoS expression I've found and then expand it out so its factorised to leave the expression in a multi-level form.

I've worked out my inital SoP expression is as followsnote: / = not)

/A . /D + /S . D + A.D

I then used De morgans theorem to get:

(/A + D) . (A + /S + /D)


Expanded out I get:

(A . /A) + (/A . /S) + (/A . /D) + (A . D) + (/S . D) + (/D . D)

Which I've got to simplify too:

(/A . /S) + (/A . /D) + (A . D) + (/S . D)

then:

/A (/S + /D) + D ( A + /S)

I'm sure though that its supposed to be equivlanet to the initial expression but there seems to be an additional /S term which I cant get rid of!

I'm not quite sure where I've gone wrong, so if someone would kindly point out where I've gone wrong that would be much appreciated!

Kind regards,

Matt

 

monkeyhead,

Lose that clunky, clumsy notation. Use instead A'B' + BC' + AB

Expand out the above expression to get the minterms A'B'(C+C') + (A+A')BC' + AB(C+C') = A'B'C + A'B'C' + ABC' + A'BC' + ABC + ABC' .

Discard one of the duplicate terms ABC' .

Now, use a Karnaugh map or the Quine-McKCuskey method to reduce the expression to A'B' + AB + A'C' or equivalently A'B' + AB + BC'

Ratch