Axial graph is the graph converted from an axial map, in which the lines are represented as nodes, and the intersections of lines as connections between the nodes.
Hillier, B. & Hanson, J. (1984), The Social Logic of Space, Cambridge University Press: Cambridge. pp.93-97;
Turner, A., Penn, A., Hillier, B., (2005) An Alogrithmic Defintion of the Axial Map. Environement and Planning B, 425-444. pp. 415-6.