Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2017/functional-programming-design-and-analysis-of-algorithms/6/a/solution

A strongly connected component is a maximal set of vertices that are mutually reachable in a directed graph; a vertex reaches itself by a length-zero path. The condensation graph, also called the SCC graph, contracts each such component to one vertex and retains directed edges between different components. It is a Directed acyclic graph, since a cycle of components would make them mutually reachable and therefore one component.
For an original seven-vertex example, take cycles , , , and add , . The three components are , and . Their condensation is the three-vertex directed chain in that order: there is no return edge from a later component to an earlier one.
Figure 1. . An original example. Internal cycles provide mutual reachability; the two forward connecting edges cannot merge distinct components. Details.

New to topics? Read the docs here!