A mathematical structure representing relationships between objects, where the objects are depicted as points and the connections between them as lines, is considered “discrete” when the set of points is finite or countably infinite and the connections are distinct and separate. These structures lack the continuous properties found in models where points can lie arbitrarily close together. For example, a social network showing friendships among individuals, or a road map indicating connections between cities, could be depicted with this type of structure.
The study of these structures is fundamental to computer science, network analysis, and combinatorial optimization. They provide a powerful tool for modeling real-world systems, enabling the development of algorithms for routing, scheduling, and resource allocation. Historically, the theoretical development of these structures is linked to early work in graph theory, with applications emerging as computing power increased and the need to analyze complex networks became paramount.