Chapter 14: Problem 16
In Exercises 15-18, determine the number of Hamilton circuits in a complete graph with the given number of vertices. 4
Short Answer
Expert verified
There are 3 Hamilton circuits in a complete graph with 4 vertices.
Step by step solution
01
Understanding the concept of Hamilton Circuits and Complete Graph
A Hamilton circuit is a path in a graph which visits each vertex exactly once and then returns to the starting vertex. A complete graph is a simple undirected graph in which every pair of distinct vertices is connected by a unique edge.
02
Recognizing the pattern
The number of Hamilton circuits in a complete graph with \(n\) vertices is \((n-1)!\), but this counts each circuit twice since each circuit can be traversed in a clockwise and counterclockwise manner. Therefore, the actual number of circuits is \((n-1)!/2\).
03
Applying the formula
The formula is \(\frac{(n-1)!}{2}\). Here, \(n\) is 4, the number of vertices in the graph. Substituting 4 into the formula gives \(\frac{(4-1)!}{2}\), which simplifies to \(\frac{3!}{2}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Complete Graph
A complete graph is a special type of graph in graph theory where every pair of distinct vertices is connected by a unique edge. This means that each vertex is directly linked to every other vertex in the graph. Complete graphs are often denoted as \(K_n\), where \(n\) represents the number of vertices in the graph.
- For example, a complete graph with 3 vertices, \(K_3\), forms a triangle. Each vertex connects to the other two.
- In a complete graph with 4 vertices, \(K_4\), the graph looks like a quadrilateral where each corner is connected to every other corner.
Graph Theory
Graph theory is a branch of mathematics focused on the study of graphs, which are structures used to model pairwise relations between objects. A graph is made up of vertices (sometimes called nodes) and edges (lines that connect pairs of vertices).
- Graphs can be used to represent many real-world systems, such as social networks, road maps, and communication networks.
- Key concepts in graph theory include paths, circuits, connectivity, and cycles.
Combinatorics
Combinatorics is a field of mathematics concerning the counting, arrangement, and combination of objects. It's often used to determine the number of possible configurations in a set. In the context of Hamilton circuits in a complete graph, combinatorics helps us to figure out the number of different ways to visit each vertex once.
- Using permutations, we can find the distinct orders to arrange \(n\) vertices in a path, accounting for symmetrical duplications.
- The formula \((n-1)!/2\) emerges from combinatorial reasoning to accurately count the Hamilton circuits without repetition.
Vertices
Vertices are the fundamental units or 'points' in a graph where edges meet. In a graph, each vertex is connected to other vertices through edges. The number of vertices gives us an insight into the size and complexity of a graph.
- Vertices can represent various objects depending on the context, like cities in a network, users in a social network, or tasks in a project plan.
- In a complete graph, every vertex is connected to all other vertices, emphasizing the importance of each vertex in maintaining the overall connectivity of the graph.