The being is derived by a difference in Lacanian ontology. This difference is the basic element in Lacanian theory that grounds the unconscious subject. Because according to Lacan, the existence of the subject can not be self-proclaimed and it is represented by a signifier. Lacan gives the name "object a" to this paradoxical being which is distinguished by this difference or lack, and uses some topological transformations in order to be able to explain the structural paradoxes in the psychological theory. (...) The aim of this study is to explore the ontology of these paradoxical situations and try to decipher the function of topology in Lacan's theory. (shrink)