Drawings
Universal point sets for planar graphs ★★★
Author(s): Mohar
We say that a set is -universal if every vertex planar graph can be drawn in the plane so that each vertex maps to a distinct point in , and all edges are (non-intersecting) straight line segments.
Question Does there exist an -universal set of size ?
Keywords: geometric graph; planar graph; universal set
Linear Hypergraphs with Dimension 3 ★★
Author(s): de Fraysseix; Ossona de Mendez; Rosenstiehl
Conjecture Any linear hypergraph with incidence poset of dimension at most 3 is the intersection hypergraph of a family of triangles and segments in the plane.
Keywords: Hypergraphs