The possibility to reach more or less easily a place in space, from another point or place.
Accessibility can be studied by graphs modelling the different positions and routes in a specified space.
B. HILLIER, who created what he calls "space syntax" as a general theory of the social organization of space (1996), uses it practically to create an accessibility hierarchy, for example for a better organization of urban space.
According to HILLIER, "People use space intuitively, much like they use grammar". This is because they have a "preference for easy journeys" (M. HAMER, 1999).
The subject is closely related to stigmergy. This hints to a much more general perception of "space syntax" in animals.