This dissertation intends to show that through the way that defines the concepts of subject and object a, Jacques Lacan summarizes what is most radical in the freudian operations of interpretation and construction, presenting an epistemology capable to formalize the operation of interpretation, to point their impasses, its limits, and to justify the need of the construction, also saying what is at stake in this. It points affinities between psychoanalysis and mathematics, and uses it resources, relying on the works of Frege, Badiou, and Russel Dedekin to define subject and object a, identifying the first with zero and identifying the second with both the excess that represent some operations in set theory, and also the irrational number. After, shows the insufficiency of the relationship of simple opposition that uses initially to link all these terms, to overcome it through a quaternary relationship – mutual implication and conjunction-disjunction – which, subverting the usual temporal and spatial references, is best suited for capture the nature of the analytical experience.