Chapter 3: Problem 57
Draw a digraph that has the given adjacency matrix. $$\left[\begin{array}{llll} 0 & 1 & 0 & 0 \\ 1 & 0 & 0 & 1 \\ 0 & 1 & 0 & 0 \\ 1 & 0 & 1 & 1 \end{array}\right]$$
Short Answer
Expert verified
Draw vertices 1, 2, 3, 4 and add edges 1→2, 2→1, 2→4, 3→2, 4→1, 4→3, 4→4.
Step by step solution
01
Understand the Adjacency Matrix
The given adjacency matrix represents a directed graph with 4 vertices. In this matrix, rows represent the start vertex and columns represent the end vertex. A value of 1 indicates a directed edge from the starting vertex to the ending vertex, while a value of 0 indicates no direct edge between those vertices.
02
Identify Edges from Matrix Row 1
The first row is \([0, 1, 0, 0]\). Here, vertex 1 has a directed edge to vertex 2, as indicated by the '1' in the second column. There are no edges from vertex 1 to vertices 3 or 4.
03
Identify Edges from Matrix Row 2
The second row is \([1, 0, 0, 1]\). This means vertex 2 has directed edges to vertices 1 and 4. The '1' in the first column indicates an edge from vertex 2 to vertex 1, and the '1' in the fourth column indicates an edge from vertex 2 to vertex 4.
04
Identify Edges from Matrix Row 3
The third row is \([0, 1, 0, 0]\). Vertex 3 has a directed edge to vertex 2. This is shown by the '1' in the second column, indicating an edge from vertex 3 to vertex 2.
05
Identify Edges from Matrix Row 4
The fourth row is \([1, 0, 1, 1]\). Vertex 4 has directed edges to vertices 1, 3, and 4 itself. The '1's in the first, third, and fourth columns indicate edges from vertex 4 to vertices 1, 3, and 4, respectively.
06
Draw the Digraph
Using the identified edges, draw a digraph with vertices 1, 2, 3, and 4. Add directed edges based on the matrix: \[\trellis_{(1,2)}\] (from 1 to 2), \[\trellis_{(2,1)}\] (from 2 to 1), \[\trellis_{(2,4)}\] (from 2 to 4), \[\trellis_{(3,2)}\] (from 3 to 2), \[\trellis_{(4,1)}\] (from 4 to 1), \[\trellis_{(4,3)}\] (from 4 to 3), and \[\trellis_{(4,4)}\] (from 4 to 4 itself).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Directed Graph
When we talk about a directed graph, or digraph, we refer to a set of vertices connected by edges, where the edges have a direction. This means each edge leads from one vertex to another specified vertex. In a directed graph:
- Each edge has a start (or source) and an endpoint.
- The direction is usually indicated by an arrow.
- It is possible for two vertices to have edges going in both directions (not necessarily forming a cycle).
- Self-loops, where a vertex is connected to itself, are allowed.
Digraph
A digraph is simply the short form of a directed graph. Every digraph is made of vertices and directed edges. While the structure may resemble that of an undirected graph, the distinguishing factor is that digraphs have directed edges.
- In mathematical terms, a digraph is denoted as a pair \( G = (V, E) \), where \( V \) is a set of vertices and \( E \) is a set of edges.
- Each edge is an ordered pair \( (u, v) \) indicating that there is a directed edge from \( u \) to \( v \).
Graph Theory
Graph theory is a field of mathematics that studies the properties and applications of graphs. A graph, in this context, is a collection of nodes connected by edges.
- These graphs can be used to solve problems related to connectivity, flow, scheduling, and more.
- Graph theory provides tools to analyze the structure of networks and predict their behavior.
Matrix Representation
Matrix representation is a method used to describe a graph using a matrix. The most common types of matrix representations in graph theory are adjacency matrices and incidence matrices.
- An adjacency matrix is a square matrix used to represent a finite graph. The elements indicate whether a pair of vertices are adjacent or not.
- For digraphs, the matrix is not necessarily symmetric, since the direction of the edge is important.
- A value of 1 signifies the presence of an edge, while 0 signifies no edge.