Diagram illustrating the neighboring pair rule for the network model, showing the locus of points (region within the solid line) that can be reversibly visited from a given reference point (x, y). B(x) is the function that defines the accessible region of the system, Δ is the maximum MC step size, x1, y1, x2, y2 correspond to the coordinates of the most distant points reachable from (x, y) in one MC step. The dashed-dotted line encloses the area accessible in one MC move from (x, y). The dashed line is a rectangle around (x, y) of dimensions Δ and 10B(x)Δ along the x and y axes, respectively,