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Exclusive or

The connector we introduce here is known in Electronics as XOR.

Definition 2.3.19   Let $ p$ and $ q$ be two propositions. The connexion $ p \nLeftrightarrow
q$ is true if, and only if, $ p$ and $ q$ have the different logical values.

This connector is described by the following table:
$ p$ $ q$ $ p \nLeftrightarrow
q$
T T F
T F T
F T T
F F F
For example, the sentence ``If Lassie is a dog or a cat, then Paris is in Europe'' is true; the premice is true because Lassie is a dog and not a cat, and the conclusion is surely true.

root 2002-06-10