[[Psychoanalysts]] have applied it to the study of [[unconscious]] [[structure]]s.
[[Topology]] (''topologie'') is a branch of [[mathematics]] which deals with the properties of figures in space which are preserved under all continuous deformations.
These properties are those of continuity, contiguity and delimitation.
The notion of space in topology is one of topological space, which is not limited to Euclidean (two- and three-dimensional space), nor even to spaces which can be said to have a dimension at all.
Topological space thus dispenses with all references to distance, size, area and angle, and is based only on a concept of closeness or neighbourhood.
==Freud==
In what have been called his two "topographies" (the first dating from 1900 and the second from 1923), [[Freud]] resorted to [[schema]]s to represent the various parts of the [[psychic apparatus]] and their interrelations.
These schemas implicitly posited an equivalence between [[psychic space]] and [[Euclidean space]].
Freud used spatial metaphors to describe the psyche in ''[[The Interpretation of Dreams]]'', where he cites G. T. Fechner's idea that the scene of action of dreams is different from that of waking ideational life and proposes the concept of 'psychical locality'.
Freud is careful to explain that this concept is a purely topographical one, and must not be confused with physical locality in any anatomical fashion.<ref>Freud, 1900a: SE V, 536</ref>
His 'first topography' divided the psyche into three systems: the conscious (Cs), the [[preconscious]] (Pcs) and the [[unconscious]] (Ucs).
The 'second topography' divided the psyche into the three agencies of the [[ego]], the [[superego]] and the [[id]].
==Lacan==
