On relations as coextensive with classes
Willard Van Orman Quine · Journal of Symbolic Logic · 1946
In a previous note I showed a new way to define the ordered pair. I made use of the notations ‘Nn’ (for class of natural numbers) and ‘Sv’ (for successor of v), remarking that they are readily defined without appeal to ordered pairs or relations. Adopting the auxiliary abbreviation: I defined the ordered pair thus: