Let Γ be a set of convex unimodal polygons in fixed position and orientation. We prove that the problem of determining whether k finger probes are sufficient to distinguish among the polygons in Γ is NP-complete for two types of finger probes. This implies that the same results hold for most interesting classes of polygons on which finger probes can be used. © 1993.
Belleville, P., & Shermer, T. C. (1993). Probing polygons minimally is hard. Computational Geometry: Theory and Applications, 2(5), 255–265. https://doi.org/10.1016/0925-7721(93)90022-X