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AQA COMP3 Graphs
Definitions about General graph theory not in the Textbook
| Term | Definition |
|---|---|
| Graph | A finite, discrete set of vertices linked by edges |
| Tree | A connected, undirected graph with no cycles |
| Rooted tree | A tree where one vertex is the starting point, and all points use this as a ‘root’ |
| Directed graph | A graph where each edge has a direction (shown by an arrow) |
| Vertex | A point where two edges connect |
| Edge | A line connecting two vertices |
| Neighbours | Adjacent vertices to a vertex |
| Degree (of a vertex) | The number of edges connected to a vertex |
| Weighted graph | A graph where each edge has been given a weight |
| Simple graph | A graph where there are no loops, and no more than 1 edge per vertex. Each edge connects two different vertices. |
| Path | A route that does not have to visit all edges |
| Circuit | A succession of edges that start and end at the same vertex |
| Cycle | A closed path where all the edges and intermediate vertices are different |
| Undirected graph | A graph with no direction (ie an edge can be traversed either way) |
| Explorer’s problem | The solution finds a route that traverses each ‘road’ (edge) exactly once before returning to the start point |
| Traveller’s problem | The solution finds a route that visits each ‘city’ (vertex) exactly once before returning to the start point |