Permutation graphとは 意味・読み方・使い方

In areas of mathematics influenced by graph theory, a permutation graph is the intersection graph of a family of line segments that connect two parallel lines in the Euclidean plane. Equivalently, given a permutation (σ₁,σ₂,σ₃,...) of the numbers 1,2,3,...n, a permutation graph has a vertex for each number 1,2,3,...n and an edge between any two numbers that are in reversed order in the permutation i.e. an edge between any two numbers where the segments cross in the permutation diagram. A permutation graph has a unique representation as a permutation diagram if and only if it is prime with respect to the modular decomposition.