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The Dual and the De Morgen Law for Logic

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The DUAL of

(P • ~Q) v (~P • Q), that is,

(P and not Q) or (not P and Q) ,

is

(P v ~Q) • ( ~P v Q), that is,

(P or not Q) and (not P or Q).

De Morgen’s laws are essentially duality principles.

1.      (P • ~Q) v (~P • Q)

2. ~ [(P • ~Q) v (~P • Q)]

3.      (~P v Q) • (P v ~Q)

See my post on the duality of the “XOR” and “IFF”, that is, the exclusive “or” and the “if and only if”, where  I derive the two definitions of the strong “or” from one anther.

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Written by peterkrey

October 16, 2009 at 5:00 pm

Posted in Logic

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