Representing Networks

The baics elements of networks are:

• A network is a system of linear features connected at intersections and interchanges.
• These intersections and interchanges are called nodes.
• The linear feature connecting any given pair of nodes is called an arc.
• Formally, a network is defined as a directed graph G = (N, A) consisting of an indexed set of nodes N with n = |N| and a spanning set of directed arcs A with m = |A|, where n is the number of nodes and m is the number of arcs.
• Each arc on a network is represented as an ordered pair of nodes, in the form from node i to node j, denoted by (i, j).
• In the GIS literature, a network arc is often called a network link.
• In addition to nodes and arcs, other basic elements of a network commonly used in GIS include paths, tours, stops, centers, and turns.
• A shortest path is the shortest or least cost path from a source node (origin) to a destination node. In practice, pathfinding is to find the shortest or most efficient way to visit a sequence of locations.
• A tour is similar to a path, but a tour is closed path, meaning that the first node and the final node on the path are the same node on the network.
• A stop is a location visited in a path or a tour.
• A center is a location where certain resources are supplied.
• A turn on a network is the transition from one arc to another arc on a network.

Citation:
F. Benjamin Zhan. (1998) Representing Networks, NCGIA Core Curriculum in GIScience, http://www.ncgia.ucsb.edu/giscc/units/u064/u064.html, created November 5, 1998

The full document can be found here.