 Figure 1 illustrates exact location and weak location. The dotted lines indicate regions (r1–r5). The shaded circle indicates a disc-shaped object, d, that is located at regions. In the diagram, d is exactly located at r4 but not at r1, r2, r3, or r5, and d is weakly located at r2, r3, r4, and r5 but not at r1.