A graphe orienté, also known as a digraph, is a type of graph in which the edges have a direction associated with them. This means that each edge connects a pair of nodes (or vertices) and indicates a one-way relationship from one node to another. In a directed graph, if there is an edge from node A to node B, it implies that the connection flows from A to B, but not necessarily vice versa.
Directed graphs are commonly used to model relationships where direction matters. For example, in social networks, a directed graph can represent followers and followees, where an edge from user A to user B indicates that A follows B. Similarly, in web page linking, a arête dirigée de la page X à la page Y signifie que X fait un lien vers Y.
Mathématiquement, un graphe orienté est défini comme une paire ordonnée G = (V, E), where V is a set of vertices (or nodes) and E is a set of directed edges. Each edge is represented as an ordered pair (u, v), indicating a directed connection from vertex u to vertex v. Directed graphs can also have properties such as weights sur les arêtes, qui peuvent représenter des distances, des coûts ou des capacités.
Les graphes orientés sont fondamentaux dans divers domaines, notamment l'informatique, la recherche opérationnelle, and théorie des réseaux. They are used in algorithms for shortest paths, network flows, and dependency resolution, among many other applications.