<P> In logic, the law of excluded middle (or the principle of excluded middle) states that for any proposition, either that proposition is true or its negation is true . It is the third of the three classic laws of thought . </P> <P> The law is also known as the law (or principle) of the excluded third, in Latin principium tertii exclusi . Another Latin designation for this law is tertium non datur: "no third (possibility) is given". </P>

Why the law of contradiction and law of excluded middle are violated in fuzzy set theory