To establish duality only requires establishing theorems which are the dual versions of the axioms for the dimension in question.

It can now be found in dual flush versions.

A dual version of this gives the Poincaré lemma.

The first two of them are dual versions (series and parallel) of the general positive feedback system.

A "dual" version of the Principle: "there is at least one person such that if anybody drinks, then he does."

Nokia has disclosed its first dual versions of X Series mobile phone.

In 1989 a dual English-Albanian version was published.

The Commodore 1572 was a dual version of the Commodore 1571 single disk drive.

The dual version is called 556.

This is the dual version of the inverse of a quaternion.