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Graph Theory
Table of Contents

Graph traversal is all about exploring connections. Walks, paths, and cycles are ways to move through a graph, each with unique rules. These concepts help us understand how information or objects flow through networks.

Open and closed walks, along with length calculations, have real-world applications. From planning delivery routes to analyzing social networks, these ideas shape how we navigate interconnected systems in everyday life.

Fundamental Concepts of Graph Traversal

Walks, paths, and cycles

  • Walk traverses graph sequence vertices and edges connecting consecutive vertices may repeat (Manhattan street grid)
  • Path special walk no repeated vertices or edges except possibly first/last (GPS route)
  • Cycle closed walk starts/ends same vertex no repeats except start/end minimum length 3 simple graphs (Monopoly board)

Open vs closed walks

  • Open walk starts ends different vertices any length (train route with multiple stops)
  • Closed walk forms loop starts ends same vertex minimum length 1 for self-loops (circular subway line)

Practical Applications

Identifying graph sequences

  • Walk verification check consecutive vertex pairs connected by edge allow repetition (social network friend chain)
  • Path verification valid walk no repeated vertices/edges except possibly first/last (delivery route)
  • Cycle verification valid walk same start/end no repeats except start/end minimum length 3 simple graphs (yearly calendar)

Length of graph structures

  • Length calculation count edges traversed weighted graphs sum edge weights (road network with distances)
  • Walk length total edge traversals including repeats (tourist sightseeing route)
  • Path length edges in path equals vertices minus one (flight itinerary)
  • Cycle length edges/vertices in cycle minimum 3 simple graphs (Olympic rings)
  • Relation to properties diameter longest shortest path between vertices girth shortest cycle (computer network topology)