Duality Principle


 * Set Theory:
 * Duality Principle for Sets


 * Order Theory:
 * Duality Principle (Order Theory)


 * Abstract Algebra:
 * Duality Principle (Boolean Algebras)
 * Principle of Duality of Huntington Algebras


 * Category Theory:
 * Duality Principle (Category Theory)


 * Projective Geometry
 * Duality Principle (Projective Geometry)

Also see

 * Definition:Dual