Effective distance

A path between two sites walks the lattice one step at a time, or hops across a loop from one leg to the other, and across a chain of loops side by side the junctions between them are free. Steps and hops both count 1, so with no loops the distance is just the separation. On the right, each pair of probes is joined by a spring as long as its effective distance, and the line links the probes in lattice order. A leg meeting a CTCF from behind may be evicted, which unloads its LEF at once; a leg whose partner is captured is immune; a leg blocked by another or by the lattice's end speeds its LEF's unloading.