ملخص: We study the hypergraph H(P) whose vertices are the points of a finite poset and whose edges are the maximal intervals in P (i.e. sets of the form I = {{v [epsilon] P: p [les] [nu] [les] q}}, p minimal, q maximal). We mention resp. show that the problems of the determination of the independence number [alpha], the point covering number [tau], the matching number v and the edge covering number p are NP-complete. For interval orders we describe polynomial algorithms and prove the Konig property (v = [tau]) and the dual Konig property (a = p). Finally we show that the (dual) Konig property is preserved by product.

لغة: إنجليزية