Duality Principle (Order Theory)

Theorem
Let $\Sigma$ be a statement about ordered sets (whether in natural or a formal language).

Let $\Sigma^*$ be the dual statement of $\Sigma$.

Also see

 * Definition:Dual Statement (Order Theory)
 * Dual Pairs, which allows for easier determination of dual statements.
 * Duality Principle (Category Theory), a more general duality principle.