A graph drawn on the plane is k-immersed (k≥ 1) in the plane if each edge is crossed by at most k other edges. By a proper k-immersion of a graph we mean a k-immersion of the …
A graph drawn on the plane is 2-immersed in the plane if each edge is crossed by at most two other edges. By a proper 2-immersion of a graph we mean a 2-immersion of the graph in …