In graph theory, Schnyder's theorem is a characterization of planar graphs in terms of the order dimension of their incidence posets. It is named after Walter Schnyder, who published its proof in 1989.
The incidence poset P(G) of an undirected graph G with vertex set V and edge set E is the partially ordered set of height 2 that has V ∪ E as its elements. In this partial order, there is an order relation x < y when x is a vertex, y is an edge, and x is one of the two endpoints of y.
The order dimension of a partial order is the smallest number of total orderings whose intersection is the given partial order; such a set of orderings is called a realizer of the partial order. Schnyder's theorem states that a graph G is planar if and only if the order dimension of P(G) is at most three.
Read more about Schnyder's Theorem: Extensions, Other Graphs
Famous quotes containing the word theorem:
“To insure the adoration of a theorem for any length of time, faith is not enough, a police force is needed as well.”
—Albert Camus (1913–1960)