Converting between SOP and POS

Thread Starter


Joined Oct 6, 2011
Convert to Product of Sums (POS) 1) AB' + C'D We would use De Morgan's Law on this. So the POS form would be: (A + B')(C' + D) 2) ac + a'bd' + a'be + a'c'de Apply De Morgan's Law again. (a + c)(a' + b + d')(a' + b + e)(a' + c' + d + e) Please tell me if those answers are correct. Thank you.


Joined Nov 25, 2009
I 'm afraid you 're wrong.

Check this out: you have F=AB'+C'D.
You did: F'=(AB'+C'D)'=(AB')(C'D)'=(A'+B)(C+D')
That means that you have found the F' in an POS form.

I suggest you make a truth table of F and produce the F' in SOP form from its '0'. Then invert it to get a POS from of F.


Joined Jul 27, 2011
Depending on the form you need the result in (canonical vs. minimized), you might have an easier time employing k-maps (minimize with the 0's) or Shannon's expansion theorem.