Librería Portfolio

Features

Begins with logic and set theory
Employs an exploratory approach
Combines topics from a transition course
Explains how to explore mathematical situations, make conjectures, and apply methods of proof
Summary

Exploring the Infinite addresses the trend toward

a combined transition course and introduction to analysis course. It

guides the reader through the processes of abstraction and log-

ical argumentation, to make the transition from student of mathematics to

practitioner of mathematics.

This requires more than knowledge of the definitions of mathematical structures,

elementary logic, and standard proof techniques. The student focused on only these

will develop little more than the ability to identify a number of proof templates and

to apply them in predictable ways to standard problems.

This book aims to do something more; it aims to help readers learn to explore

mathematical situations, to make conjectures, and only then to apply methods

of proof. Practitioners of mathematics must do all of these things.

The chapters of this text are divided into two parts. Part I serves as an introduction

to proof and abstract mathematics and aims to prepare the reader for advanced

course work in all areas of mathematics. It thus includes all the standard material

from a transition to proof´ course.

Part II constitutes an introduction to the basic concepts of analysis, including limits

of sequences of real numbers and of functions, infinite series, the structure of the

real line, and continuous functions.



Features

Two part text for the combined transition and analysis course
New approach focuses on exploration and creative thought
Emphasizes the limit and sequences
Introduces programming skills to explore concepts in analysis
Emphasis in on developing mathematical thought
Exploration problems expand more traditional exercise sets



Table of Contents

Fundamentals of Abstract Mathematics

Basic Notions

A First Look at Some Familiar Number Systems

Integers and natural numbers

Rational numbers and real numbers

Inequalities

A First Look at Sets and Functions

Sets, elements, and subsets

Operations with sets

Special subsets of R: intervals

Functions

Mathematical Induction

First Examples

Defining sequences through a formula for the n-th term

Defining sequences recursively

First Programs

First Proofs: The Principle of Mathematical Induction

Strong Induction

The Well-Ordering Principle and Induction

Basic Logic and Proof Techniques

Logical Statements and Truth Table

Statements and their negations

Combining statements

Implications

Quantified Statements and Their Negations

Writing implications as quanti ed statements

Proof Techniques

Direct Proof

Proof by contradiction

Proof by contraposition

The art of the counterexample

Sets, Relations, and Functions

Sets

Relations

The definition

Order Relations

Equivalence Relations

Functions

Images and pre-images

Injections, surjections, and bijections

Compositions of functions

Inverse Functions

Elementary Discrete Mathematics

Basic Principles of Combinatorics

The Addition and Multiplication Principles

Permutations and combinations

Combinatorial identities

Linear Recurrence Relations

An example

General results

Analysis of Algorithms

Some simple algorithms

Omicron, Omega and Theta notation

Analysis of the binary search algorithm

Number Systems and Algebraic Structures

Representations of Natural Numbers

Developing an algorithm to convert a number from base

10 to base 2.

Proof of the existence and uniqueness of the base b representation of an element of N

Integers and Divisibility

Modular Arithmetic

Definition of congruence and basic properties

Congruence classes

Operations on congruence classes

The Rational Numbers

Algebraic Structures

Binary Operations

Groups

Rings and fields

Cardinality

The Definition

Finite Sets Revisited

Countably Infinite Sets

Uncountable Sets

Foundations of Analysis

Sequences of Real Numbers

The Limit of a Sequence

Numerical and graphical exploration

The precise de nition of a limit

Properties of Limits

Cauchy Sequences

Showing that a sequence is Cauchy

Showing that a sequence is divergent

Properties of Cauchy sequences

A Closer Look at the Real Number System

R as a Complete Ordered Field

Completeness

Why Q is not complete

Algorithms for approximating square root 2

Construction of R

An equivalence relation on Cauchy sequences of rational

numbers

Operations on R

Verifying the field axioms

Defining order

Sequences of real numbers and completeness

Series, Part 1

Basic Notions

Exploring the sequence of partial sums graphically and

numerically

Basic properties of convergent series

Series that diverge slowly: The harmonic series

Infinite geometric series

Tests for Convergence of Series

Representations of real numbers

Base 10 representation

Base 10 representations of rational numbers

Representations in other bases

The Structure of the Real Line

Basic Notions from Topology

Open and closed sets

Accumulation points of sets

Compact sets

Subsequences and limit points

First definition of compactness

The Heine-Borel Property

A First Glimpse at the Notion of Measure

Measuring intervals

Measure zero

The Cantor set

Continuous Functions

Sequential Continuity

Exploring sequential continuity graphically and numerically

Proving that a function is continuous

Proving that a function is discontinuous

First results

Related Notions

The epsilon-delta? condition

Uniform continuity

The limit of a function

Important Theorems

The Intermediate Value Theorem

Developing a root-finding algorithm from the proof of the

IVT

Continuous functions on compact intervals

Differentiation

Definition and First Examples

Properties of Differentiable Functions and Rules for Differentiation

Applications of the Derivative

Series, Part 2

Absolutely and Conditionally Convergent Series

The rst example

Summation by Parts and the Alternating Series Test

Basic facts about conditionally convergent series

Rearrangements

Rearrangements and non-negative series

Using Python to explore the alternating harmonic series

A general theorem

A Very Short Course on Python

Getting Stated

Why Python?

Python versions 2 and 3

Installation and Requirements

Integrated Development Environments (IDEs)

Python Basics

Exploring in the Python Console

Your First Programs

Good Programming Practice

Lists and strings

if . . . else structures and comparison operators

Loop structures

Functions

Recursion