/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 13 Prove that any graph with a fini... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Prove that any graph with a finite mimber of vertices can be drawn in three dimensions so that no edges intersect.

Short Answer

Expert verified
Every finite graph can be drawn without edge intersections in 3D space.

Step by step solution

01

Understanding the Problem

We need to show that any finite graph can be drawn in three dimensions without any two edges crossing each other.
02

Graph Representation

Consider a graph with vertices and edges. By representing vertices as points and edges as straight lines connecting the points, we seek to arrange these points in such a way that no two edges cross.
03

Applying the Dimension Argument

In a two-dimensional plane, it is not always possible to avoid intersections of edges in a graph with many vertices. However, when extended to three dimensions, there is more space to separate these edges.
04

Embedding in Three Dimensions

Place each vertex of the graph at a distinct point in three-dimensional space (for instance, using integer coordinates to ensure uniqueness and distinguishability of the vertices).
05

Ensuring Non-Intersecting Edges

Connect the vertices by straight lines representing the edges. With three degrees of freedom in 3D space, arrange these lines so that they do not intersect with each other. This can always be achieved because there is enough space to adjust the position of vertices and edges.
06

Conclusion

Since vertices in three-dimensional space can always be placed distinctively, and edges can be drawn as straight lines without intersections, it proves that any finite graph can be drawn without any edges intersecting in three dimensions.

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.

Three-Dimensional Graph Embedding
Three-dimensional graph embedding is a fascinating concept in graph theory. Imagine you have a web of points connected by lines, which forms a graph. Now, if you take this graph and attempt to place it in three dimensions, you are undertaking a "three-dimensional graph embedding." Unlike in two dimensions, where crowded graphs can easily get tangled, three dimensions offer ample space to spread out the elements.
Visualize this as moving from a crowded city street to an open field; suddenly, there's more room to maneuver. Each vertex (the points in our web) can be placed at a unique position in a 3D space. You might use simple coordinates like (1, 2, 3) for one vertex and (4, 5, 6) for another. This ensures that each vertex is distinct. The extra space provided by 3D allows for vertices and edges to be arranged with less restriction, significantly reducing the chances of lines overlapping.
Graph Drawing
Graph drawing is the art of visually representing a graph. You might think of it as a blueprint or map of how vertices (nodes) and edges (lines connecting nodes) are arranged. When drawing graphs, one of the main goals is to depict the structure clearly and without confusion. Whether in two or three dimensions, the process remains focused on clarity and precision.
  • Two Dimensions: On paper or a screen, we attempt to spread out the elements so that crossing lines are minimized. But often, due to limited space, some overlap is inevitable.
  • Three Dimensions: Drawing in 3D introduces a new realm of possibility. More space often means less overlap of edges, as additional height can be explored, aside from just width and length.
Effective graph drawing communicates the connectivity of the graph intuitively, allowing anyone looking at it to grasp the structure without needing complex explanations. This is crucial for understanding and working with graphs in education, computer science, and network analysis.
Non-Intersecting Edges
One of the most critical aspects of graph drawing, especially in three dimensions, is ensuring non-intersecting edges. An edge represents a connection between two vertices. When drawing edges in a graph, intersecting lines can easily cause confusion about which points are actually connected.
In three-dimensional space, there is an increased degree of freedom—edges can be arranged not just side-by-side but also over and under each other. This freedom makes it possible to avoid intersections by carefully positioning each vertex and the lines that connect them.
For instance, consider two edges. In 2D, these might cross each other, making it hard to see the connection paths. In 3D, you can simply elevate one edge over the other.
  • This helps in visual clarity and reduces misunderstandings.
  • It's often achieved using distinct coordinate points so that lines do not compete for the same plane space.
This ensures a clean, distinct layout where each edge clearly represents its unique path, contributing to the overall understanding and analysis of the graph's structure.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

What is the maximum number of edges in an undirected graph with eight vertices?

Let \(d\) be a positive integer, and let \(a_{1}, a_{2}, \ldots a_{d}\) be positive integers greater than or equal to two. The mesh graph \(M\left(a_{1}, a_{2} \ldots \ldots, a_{d}\right)\) has vertices of the form \(x=\left(x_{1}, x_{2}, \ldots, x_{d}\right)\) where \(1 \leq x_{i} \leq a_{i} .\) Two vertices \(x\) and \(y\) are adjacent if and only if \(\sum_{i=1}^{d}\left|x_{i}-y_{i}\right|=1\). In other words, two adjacent vertices must differ in only one coordinate and by a difference of \(1 .\) (a) What is the chromatic mumber of \(M\left(a_{1}+a_{2} \ldots \ldots, a_{d}\right) ?\) (b) For what pairs \(\left(a_{1}, a_{2}\right)\) does \(M\left(a_{1}, a_{2}\right)\) have a Hamiltonian circuit? (c) For what triples \(\left(a_{1}, a_{2}, a_{3}\right)\) does \(M\left(a_{1}, a_{2}, a_{3}\right)\) have a Hamiltonian circuit?

(a) Suppose the edges of a \(K_{6}\) are colored either red or blue. Prove that there will be either a "red \(K_{3}^{\prime \prime}\) (a subset of the vertex set with three vertices connected by red edges) or a "blue \(K_{3}{ }^{\pi}\) or both. (b) Suppose six people are selected at random. Prove that either there exists a subset of three of them with the property that any two people in the subset can communicate in a common language, or there exist three people, no two of whom can communicate in a common language,

Prove that if an undirected graph has a subgraph that is a \(K_{3}\) it then its chromatic number is at least \(3 .\)

A particular set of dominoes has 21 tiles: \((1,1),(1,2), \ldots(1,6),(2,2),(2,3), \ldots,(6,6)\). Is it possible to lay all 21 tiles in a line so that each adjacent pair of tile ends matches (that is, each 1 abuts a \(1,\) and so on \() ?\)

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.