What is the Difference Between Directed and Undirected Graph?

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The main difference between directed and undirected graphs lies in the direction of their edges. Here are the key differences:

  • Directed Graphs:
  1. Edges have a specific direction, indicating a one-way relationship.
  2. Edges connect one vertex to another with arrows, showing the direction of the relationship.
  3. Asymmetrical, as the edges are one-way and not necessarily reciprocal.
  4. Suitable for modeling processes or workflows with directional relationships.
  5. Less memory-efficient than undirected graphs, as they require more storage for edge directions.
  • Undirected Graphs:
  1. Edges have no direction, indicating a two-way relationship.
  2. Arrowless connections between vertices.
  3. Symmetrical, as the relationship is reciprocal.
  4. Suitable for modeling relationships that are not hierarchical, such as "is a friend of."
  5. More memory-efficient than directed graphs, as they require less storage for edge directions.

In summary, directed graphs have edges with a specific direction, while undirected graphs have edges without a direction. The choice between directed and undirected graphs depends on the application and the nature of the relationships being modeled.

Comparative Table: Directed vs Undirected Graph

Here is a table comparing the differences between directed and undirected graphs:

Feature Undirected Graph Directed Graph
Definition Graph where edges do not have a specific direction and are bidirectional in nature. Graph where edges have a specific direction and are unidirectional in nature.
Representation Efficient traversal in both directions. Efficient traversal in the specified direction.
Memory Efficiency Requires less memory, hence memory-efficient. Suitable for modeling processes or workflows, but more complex than undirected graphs.
Algorithm Application Limited modeling capability for directed relationships. Complex as compared to undirected graphs.
Traversal Inefficient traversal without additional checks. Direction of traversal is enforced by the presence or absence of edges between nodes.
Asymmetry Symmetry between relationships provided. Asymmetry present, as edges are all one-way.
Connectivity Graph may be connected in either direction. Graph may have more than one way to traverse from one vertex to another.

In summary, undirected graphs have edges without a specific direction, allowing for efficient traversal in both directions and requiring less memory. Directed graphs, on the other hand, have edges with specific directions, making them more suitable for modeling processes or workflows, but they are more complex and require additional checks for traversal.