How do undergraduates do mathematics?

How do undergraduates do mathematics?

A guide to studying mathematics at Oxford University

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Contents

0 Preface

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Part I

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1 University study

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1.1 Pattern of work . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Lectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.3 Tutorials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4 Cooperation with fellow students . . . . . . . . . . . . . . . . 15

1.5 Books and libraries . . . . . . . . . . . . . . . . . . . . . . . . 16

1.6 Vacation work . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2 University mathematics

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2.1 Studying the theory . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2 Problem-solving . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.3 Writing mathematics . . . . . . . . . . . . . . . . . . . . . . . 26

3 The perspective of applied mathematics

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3.1 Pure and applied mathematics . . . . . . . . . . . . . . . . . . 29

3.2 Solving problems in applied mathematics . . . . . . . . . . . . 30

3.3 Writing out the solution . . . . . . . . . . . . . . . . . . . . . 34

Part II

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4 The formulation of mathematical statements

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4.1 Hypothesis and conclusions . . . . . . . . . . . . . . . . . . . 42

4.2 "If", "only if", and "if and only if" . . . . . . . . . . . . . . . 46

4.3 "And" and "or" . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.4 "For all" and "there exists" . . . . . . . . . . . . . . . . . . . 55

4.5 What depends on what? . . . . . . . . . . . . . . . . . . . . . 58

5 Proofs

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5.1 Counterexamples . . . . . . . . . . . . . . . . . . . . . . . . . 61

5.2 Constructing proofs . . . . . . . . . . . . . . . . . . . . . . . . 64

5.3 Understanding the problem . . . . . . . . . . . . . . . . . . . 66

5.4 Experimentation . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.5 Making the proof precise . . . . . . . . . . . . . . . . . . . . . 75

5.6 What can you assume? . . . . . . . . . . . . . . . . . . . . . . 81

5.7 Proofs by contradiction . . . . . . . . . . . . . . . . . . . . . . 82

5.8 Proofs by induction . . . . . . . . . . . . . . . . . . . . . . . . 87

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A Some symbols

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0 Preface

The first version of this guide was written by Charles Batty in 1994. His preface to the first version is retained below. Nick Woodhouse contributed Chapter 3 on studying applied mathematics.

It was updated in September 2014 by Richard Earl, Frances Kirwan and Vicky Neale, and therefore the opinions expressed should be attributed to a range of people.

In the last twenty years, there have been several books and documents written for students beginning to study mathematics at university. Here are a few.

Lara Alcock, How to study for a mathematics degree, (Oxford University Press, 2012)

Kevin Houston, How to think like a mathematician, (Cambridge University Press, 2009)

Tom Leinster, Tips on mathematical writing, . ac.uk/~tl/tips.pdf

Preface to the first edition

In one sense, mathematics at university follows on directly from school mathematics. In another sense, university mathematics is self-contained and requires no prior knowledge. In reality, neither of these descriptions is anything like complete. Although it would be impossible to study mathematics at Oxford without having studied it before, there is a marked change of style at university, involving abstraction and rigour. As an undergraduate in any subject, your pattern and method of study will differ from your schooldays, and in mathematics you will also have to master new skills such as interpreting mathematical statements correctly and constructing rigorous proofs.

These notes are an introduction to some of these aspects of studying mathematics at Oxford. Their purpose is to introduce you to ideas which you are unlikely to have met at school, and which are not covered in textbooks. It is not expected that you will understand everything on first reading; for instance, some of the examples may be taken from topics which you have not covered at school, and some of the material in Part II needs time to be absorbed. With the exception of a few fleeting references to physical applied mathematics, the notes discuss topics which are common to all the mathematics courses in Oxford, so they should be almost as useful for

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students in Mathematics & Computer Science, Mathematics & Philosophy, and Mathematics & Statistics as for those in Mathematics. It is hoped that after a term or two you will have absorbed all the advice in the notes and that they will become redundant. For this reason, there is no attempt to cover any topics which will not arise until later in your course, e.g. examinations and options.

It is important to appreciate that the notes are an introduction to studying mathematics, not an introduction to the mathematics; indeed, there is very little genuine mathematics in the notes. In particular, the notes attempt to answer the question: How to study mathematics? but not the questions: Why study mathematics? or: What topics do we study in university mathematics? Occasionally, the notes consider the question: Why do we do mathematics the way we do? but the emphasis is on How? not Why? Consequently, the notes have some of the style of a manual, and they will not make the most exciting of reads. You are therefore recommended to seek another source for the other questions. At present, the best such book known to me is Alice in Numberland, by J. Baylis and R. Haggarty (Macmillan). Indeed, I recommend that you read Alice in Numberland (at least a substantial part of it) before you read these notes (at least before you read Part II).

Your tutors are likely to offer their own advice which sections of these notes you should read at what time and what else you should read, and to set you some problems. I will therefore refrain from proffering guidance except to say that Part I will be most useful if it is read before your courses start in the first full week after your arrival in Oxford. It should not take long to read this part as it contains very little mathematics. Chapter 1 is the only chapter where some of the content is specific to Oxford (on the other hand, much of its content is not specific to mathematics).

Part I contains many instructions and imperatives: Do this; Do that; You should . . . They are to be regarded as recommendations or advice, rather than rules which must be religiously observed. (Indeed, it is unlikely that anyone would have time or inclination to carry out all the tasks suggested.) Students differ in temperament and intellect, so what suits one undergraduate will not necessarily suit another. It is up to you to work out your own workstyle; it is hoped that these notes will assist you. It is possible that your tutor will disagree with some of the advice. What I have included is what I regard as good advice in general. I believe that all tutors will agree with most of what I have written, and I am confident that students who follow most of the advice will be more successful, in general, than those who ignore it. Nevertheless, any opinions expressed in these notes are my own (and, in the case of Chapter 3, those of Nick Woodhouse); they do not necessarily

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