Book of Proof
A transition from calculation to proofs, with sets, induction and cardinality. Selected solutions help self-study; it is preparation rather than an advanced subject text.
Proof-writing starts with knowing exactly what a statement allows you to assume and what it asks you to produce. Hammack separates logical language from direct proof, contradiction, counterexamples and induction, making it possible to repair one weakness at a time. Ernst takes a problem-led route in which constructing arguments is the main activity. Choose Hammack when you need explicit models of written reasoning; choose Ernst when you want sustained practice developing a claim before seeing a finished proof.
Book of Proof, third edition — Richard Hammack. Read sections 2.7 and 2.10 on quantifiers and negation; 4.3, 5.1 and 6.1 on proof methods; 5.3 on writing; then 9.1 and 10.1 on counterexamples and induction.
Rewrite a quantified statement in words, negate it, and test both versions on small examples. For each proof, name the domain and record where every hypothesis enters. Spend a second session revising an earlier argument for an unfamiliar reader. A correct answer with an unstated induction hypothesis or an undefined variable is a prompt for revision.
Target quantifiers, counterexamples or induction without restarting an entire mathematics course.
Read sections 2.7 and 2.10 on quantifiers and negation; 4.3, 5.1 and 6.1 on proof methods; 5.3 on writing; then 9.1 and 10.1 on counterexamples and induction.
Source · Checked 2026-10-16
Develop independence in constructing proofs and comparing classmates' arguments.
Locate the logic, sets, induction, relations and functions portions through the listed author edition; section numbering was not inherited.
Source · Checked 2026-10-11
Book of Proof exercises and selected solutions. Exercise sets following sections 2.10, 4.3, 5.1, 6.1 and 10.1; compare with the corresponding headings in Solutions.. Exercises provided; a public Solutions section starts on printed page 292. Treat it as selected solutions, not a complete answer key.
Try a proof or calculation before opening the hint. These solutions address the checks below, not the exercises in the linked textbooks.
Negate: for every real x there is a real y with y > x. Then determine the truth of the original statement and its negation.
Reverse each quantifier, then negate the inequality. For the original statement, try choosing in terms of .
The original statement is . It is true: given , choose .
Its negation is . This would assert a largest real number. It is false, since for any proposed , the choice violates the required inequality. Notice that the choice of is allowed to depend on ; swapping the quantifiers would ask a different question.
Prove that an integer n is even if and only if n squared is even, giving each implication separately.
One direction follows by writing . For the other, prove the contrapositive using the form of an odd integer.
If for some integer , then is even.
For the converse, suppose that is odd. Write . Then
so is odd. The contrapositive gives: if is even, then is even. Both directions are needed for the equivalence.
Prove by induction that 1 + 3 + ... + (2n - 1) = n squared for every integer n >= 1.
After assuming the formula for , identify the next odd summand before doing any algebra.
For , the sum is . Suppose the statement holds for an integer . The next odd summand is , so
This proves the induction step. Together with the base case, it establishes the identity for every integer . The induction hypothesis was used to replace only the first summands by , not to assume the desired formula at .
Already comfortable with this? Skip the introductory proof-method readings if you can complete all three checks, state each domain and hypothesis, and revise a proof so every inference is justified. Review quantifiers alone if negation is the remaining gap.
Review the prerequisites · Compare the full subject collection
A transition from calculation to proofs, with sets, induction and cardinality. Selected solutions help self-study; it is preparation rather than an advanced subject text.
A problem-led introduction to logic, sets, induction, relations and functions. Suitable for developing proof-writing by doing.
A transition to abstract mathematics through examples and proof exercises. The source lists the author text and supporting videos.
Emphasizes communicating arguments clearly, evaluating proposed proofs and learning through progress checks. Includes sets, induction and elementary number theory.
Introduces logical structure and techniques for reading and writing proofs. Institutional access and print availability are separate from free preview access.
An inquiry-based route from patterns and conjectures to justification. Read it for active exploration rather than as a catalogue of proof templates.
A transition course on mathematical reasoning, sets and functions. Use the exercises to learn how definitions drive proofs.
Discusses mathematical reading, writing, proof construction and problem solving. A companion to first proof-based courses, not a substitute for solving their exercises.
Uses accessible mathematical problems to develop proof technique and mathematical judgement.
Organizes proof construction into explicit reasoning strategies. The official companion offers supporting material, not the complete textbook.
A bridge course connecting elementary logic with sets, functions, equivalence relations, induction and cardinality.
English title: Mathematical Method. Introduces logic, proof strategies, induction and the analysis–synthesis approach to mathematical problem solving.
English title: Introduction to Abstract Mathematics. Builds a foundation in propositional and predicate logic, sets, functions, orders and induction, with exercises and challenges.
Dialogues and explanations explore why definitions and proofs arise in algebra, analysis, geometry and logic.
Discusses the roles of learning, persistence and cooperation in mathematical research.
Lockhart argues for imagination and discovery in school mathematics through a deliberately polemical essay.
A broad bridge from undergraduate subjects toward first-year graduate ideas. Some planned chapters and exercises are unfinished; it is not a substitute for a full course in each field.
A collection of elegant arguments across several fields. Read after learning basic proof techniques; it is not a systematic first curriculum.
Uses number systems, polynomials and determinants to practise reading and constructing longer mathematical arguments.
Gowers discusses theory-building and problem-solving, using combinatorics to examine mathematical value and communication.
Thurston reflects on understanding, proof and communication, drawing on foliations and three-dimensional geometry.
Examines multiple sources of mathematical value and the connections that can develop between them.
Tao considers how mathematical practice and collaboration might respond to research-capable AI tools.
Advice and linked essays address mathematical exposition, revision and communication with readers.
Discusses mathematical reasoning, geometry, hypotheses and physical theories from Poincaré’s historical viewpoint.