NP-harte Probleme für minimale Polygonüberdeckungen. (NP-hard problems for minimal polygon coverings) (Q811138)

A simple polygon P is visible from a set \(L\subseteq P\) if and only if for any point \(y\in P\) there exists a point \(x\in L\) such that xy\(\subseteq P\). If P is visible from L, then L is called a cover of P. On the basis of classification of covers, problems of computing the number of components of minimal covers (covers of a certain type consisting of a minimal number of components) are characterized to be NP- hard.